Production cycle of phytoplankton. Factors influencing the development of phytoplankton Main factors influencing the productivity of phytoplankton

V.A. Chugainova, I.Yu. Makedonskaya Northern branch of PINRO, Arkhangelsk, Russia e-mail: [email protected]

Primary production, the greatest contribution to which is made by planktonic algae, along with allochthonous organic substances entering the reservoir, forms the material and energy basis of all subsequent stages of the production process.

Thanks to the development of methods for studying primary production, the overall biological productivity of a reservoir has received quantitative expression. The need for quantitative characterization of organic substances synthesized during plankton photosynthesis clearly appears when solving many issues and practices of hydrobiology. But, despite this, the knowledge of the production characteristics of phytoplankton leaves much to be desired.

Materials and methods

Studies of the primary productivity of phytoplankton were carried out from July 7 to July 21, 2007 at the SevPINRO station in the Pechakovskaya Salma Strait (Solovetsky Islands) at daily stations (a total of 14 determinations of gross primary productivity). In addition, one of the goals of our research was qualitative and quantitative daily changes in phytoplankton. In this regard, 13 phytoplankton samples were collected and processed in the surface layer of the coastal zone. Phytoplankton samples were taken on July 14-15 after two hours. The set of observations, along with qualitative and quantitative indicators of phytoplankton, included determination of temperature, water salinity, and oxygen content.

Analyzes of seawater samples were carried out using methods generally accepted in hydrochemical practice. Oxygen dissolved in water was determined by the volumetric Winkler method (Manual..., 2003). Incubation of water samples to determine the intensity of photosynthesis was carried out in dark and light flasks at sea water temperature and natural light. Samples for the pigment composition of phytoplankton were filtered through Vladipor membrane filters with a diameter of 35 mm and a pore size of 0.65 microns. Filter samples were stored in a freezer in a container with silica gel. Microalgae pigments were determined in laboratory conditions using standard methods. The optical densities of the extract were measured at wavelengths of 480, 630, 647, 664 and 750 nm. The concentration of chlorophyll “a” was calculated using the formulas of Jeffrey and Humphrey (Jeffrey S.W., Humphrey G.F., 1975).

As a result of the research, a number of observations were obtained on changes in gross primary production over 15 days, and the daily dynamics of qualitative and quantitative indicators of phytoplankton were identified.

Results and its discussion

According to our observations, the values ​​of gross primary production (PPtotal) in Pechakovskaya Salma varied in a wide range - 0.33-1.65 mgO2/l/day (which corresponds to 124-619 mgC/m3/day), the average value was 0. 63 mgO2/l/day (256.4 mgC/m3/day). The maximum values ​​were recorded in the last two days, which is probably due to more favorable weather conditions (Fig. 1). These values ​​basically correspond to the PPtotal obtained in previous years in this area (Chugainova, Makedonskaya, 2007).

In general, gross photosynthesis changed quite evenly over 15 days, showing a wave-like character.

It should be noted that stable natural conditions were observed during this period. Thus, the water temperature varied in the range from 8.4 ° C at the beginning of observations to 10 ° C at the end (average 9.66 ° C), salinity varied in the range of 26.2-26.9%% (with an average of 26.6 %o ). The weather conditions were also almost uniform.

Destruction indicators during the entire observation period exceeded the PPtotal, and only at the end of the period their values ​​were close to balance. On average, destruction was 414.4 mg C/m 3 /day (with a variability of 86.3 - 742.5 mg C/m 3 / day).

Daily changes in the abundance, biomass, and complex of dominant phytoplankton species were subject to some fluctuations. Biomass varied from 94.8 to 496.44 μg/l, and abundance - from 4860 to 18220 cells/l (Fig. 2). Average daily values ​​of abundance and biomass were 10277 cells/l and 311.21 μg/l, respectively .

The total number of microalgae taxa in the July samples fluctuated from 13 to 25 during the day. A total of 45 taxa were discovered during the study. The complex of dominant taxa of July phytoplankton included: cryptophytes - Leoucocryptos marina; green - Piramimonas sp., small Chlorococales; diatoms - Thalassiosira Nordenscioldii, Leptocylindrus danicus, Detonula confervacea, L icmophora paradoxa; dinophytes - Gymnodinium arcticum. The complex of microalgae is quite common for this area in the summer season (Makedonskaya, 2007).

The main role in the photosynthetic process is played by chlorophyll “a”; all other pigments only transfer the energy they absorb to chlorophyll “a”. Thus, the content of chlorophyll “a” is the most important characteristic of the photosynthetic activity of phytoplankton, from which it is also possible to determine schematic indicators of phytoplankton biomass (see Fig. 2). The study of quantitative relationships between various phytoplankton pigments allows us to judge the predominance of a particular group of algae in sea water. Thus, the bulk of marine phytoplankton consists of diatoms and peridinium algae, which contain chlorophylls “a” and “c”. Definition of even small

the amount of chlorophyll “b” indicates the development of small flagellated (green) and blue-green algae. The relationships between algae pigments also characterize the physiological state of the phytoplankton population. Chlorophyll “a” accounts for 51% of phytopigments. Chlorophyll “b” present in the chloroplasts of green algae accounts for 24%, the share of chlorophyll “c”, which is found in the cells of diatoms, dinophytes and other divisions of algae, accounts for 25%. This ratio of pigments indicates intense photosynthetic activity of phytoplankton. This is indirectly confirmed by the oxygen saturation of the waters, which during the daily station was 110-130% sat., as well as by the PPtotal indicators.

An attempt to compare the values ​​of chlorophylls, biomass, and the abundance of microalgae with the tidal cycle showed that their concentrations do not depend on the phase of the tide. And they are in antiphase with the content and saturation of water with oxygen.

In summer, in the area of ​​the Pechakovskaya Salma Strait, high values ​​of primary phytoplankton production were noted, comparable to spring ones.

Changes in the qualitative and quantitative composition of phytoplankton do not have obvious differences during the day. The reason for this, in all likelihood, is the fairly stable hydrological and hydrochemical regime of the Pechakovskaya Salma waters during the observation period.

Additional research will be required to clarify daily and seasonal changes in the phytoplankton community in this area.

Literature

Makedonskaya I.Yu., 2007. On the seasonal and interannual dynamics of phytoplankton in the Pechakovskaya Salma of the Onega Bay of the White Sea // Problems of studying, rational use and protection of natural resources of the White Sea - Materials of the X International Conference. Arkhangelsk. P.154-158.

Chugainova V.A., Makedonskaya I.Yu., 2008. Seasonal changes in primary productivity and chlorophyll “a” in the Solovetsky Islands area. //Marine coastal ecosystems: algae, invertebrates and their products. Abstracts of reports of the 3rd International Scientific and Practical Conference. Vladivostok: TINRO-center. P.163-164.

Guidelines for the chemical analysis of sea and fresh waters during environmental monitoring of fishery reservoirs and promising fishing areas of the World Ocean., 2003. M.: VNIRO Publishing House. -202 s.

Jeffrey S.W., Humphrey G.F., 1975. New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton // Biochem. und Physiol. Pflanz. Bd. 167. No. 2. P. 191-194.

PHYTOPLANKTON PRIMARY EFFICIENCY IN PECHAKOVSKAJA SALMA BELT OF THE WHITE SEA DURING SUMMER PERIOD

V.A. Chugajnova, I.J. Makedonskaya

Northern Branch of PINRO, Arkhangelsk, Russia e-mail: [email protected]

Investigations of phytoplankton primary efficiency were spent on July 7-21, 2007 on SevPINRO permanent establishment in Pechakovskaja Salma belt, (Solovetskiye Islands) at daily stations (14 definitions of total primary efficiency in all). On our observations, values ​​of total primary production

(TPP) in Pechakovskaja Salma varied in a wide range - 0.33-1.65 mgO 2 /l/day (that corresponds 124 - 619 mgC/m 3 /day), average value has made 0.63 mgO 2 /l/day (256.4 mgC/m 3 /day). As a whole, total photosynthesis within 15 day changed in enough regular intervals, showing wavy character. Daily changes in number, a biomass and a complex of a dominating phytoplankton species were also exposed to some fluctuations. The biomass changed within the limits of from 94.8 up to 496.44 mkg/l, and number - from 4860 up to 18220 cells/l. Daily average values ​​of number and a biomass have made 10277 cells/l and 311.21 mkg/l, accordingly.

The productivity of water bodies - their ability to create organic matter - is usually assessed by the level of primary plankton production, most often calculated for a year or growing season. A vast literature is devoted to studies of the primary production of plankton. Its most complete analysis in relation to continental water bodies was carried out by V.V. Bouillon, which allowed him to establish many regularities (Bouillon, 1994). The productivity of lotic ecosystems is less known. However, the production capabilities of reservoirs or watercourses can be assessed more fully taking into account the production of plankton algae, macrophytes, periphyton, phytobenthos. The total production of all autotrophs, reflecting the size of the primary reservoir, will be called the primary production of the ecosystem.

The primary production of the ecosystem as a whole (P re) consists of the primary production of plankton, periphyton, macrophytes, etc. In different reservoirs, the contribution of each component to the primary production of the ecosystem is different (Alimov, 1989). In rivers and some lakes, the total primary production is determined mainly by the production capabilities of macrophytes and periphyton; in most lakes, the main role in the creation of primary production belongs to plankton algae (Table 5).

In general, there is a tendency to increase the role of macrophytes and periphyton in the formation of primary ecosystem production in shallow lakes. In deep-sea lakes, primary production is created mainly due to the photosynthetic activity of phytoplankton. The importance of periphyton among primary producers depends on the characteristics of specific water bodies.

Table 5

Share (%) of the production of phytoplankton algae, macrophytes, periphton in the primary production of reservoirs and watercourses (from Function ..., 1980)

Generalization of data on the production of macrophytes (aerial-water and submerged) and primary production of plankton allowed M.V. Martynova (1984) distinguished five groups of reservoirs depending on their ratio. The share of macrophyte production from the total primary production (macrophytes and plankton) in reservoirs of the first group was more than 60, the second - 59-30, the third - 29-11, the fourth - 5-10, the fifth - less than 5%.

Calculations performed by the author based on the data of M.V. Martynova (groups 1, 2, 4) showed that with an increase in the primary production of plankton, the production of macrophytes (P m) increases, which can be expressed in the form of equations of a linear function (all in gC/ m 2 year):

1st group - Р m = 1.296 Р р + 65.98, R 2 = 0.68,

2nd group - Р m = 1.54 Р р - 93.949, R 2 =0.83

3rd group - Р m = 0.26 Р р - 0.47, R 2 = 0.85 (calculated by Martynova),

4th group - Р m = 0.117 Р р - 5.007, R 2 = 0.83,

5th group - Р m = 0.025 Р р + 0.31, R 2 = 0.83 (calculated by Martynova).

The rate of change in the value of macrophyte production and the value of plankton production (the first derivatives of the above equations) generally decreases in the direction from the 1st to the 5th group of reservoirs. In those reservoirs in which the production of macrophytes accounts for from 60 to 90% of the primary production of the reservoir, with an increase in plankton production, the production of macrophytes increases most sharply and, conversely, in reservoirs where over 90% of the primary production is plankton production, the growth of macrophyte production occurs at low rates. At the same time, according to Martynova, the area of ​​overgrowth of a reservoir with macrophytes (G) increases in proportion to the rate of increase in the ratio between macrophyte production and primary plankton production (Fig. 20):

G = 53.013*( d P m / d P p) 1.001; R 2 =0.73.(24)

At the same time, the area overgrown with macrophytes increases sharply as the reservoir capacity increases (E = h/h max) (Fig. 21):

G = 757.67*E 4.35; R2 = 0.65 (25)

From the above equations it is easy to see that:

d P m / d P p = 8.47*E,

those. Macrophyte production relative to primary plankton production is greater in shallower water bodies. Typically, the average depth in reservoirs of the first group does not exceed 1-1.5 m, while reservoirs of the 4th and especially the 5th groups can have average depths of 10 m or more. In the first case, macrophytes occupy almost 100% of the water area, in the latter the area is overgrown macrophytes makes up fractions or a few percent of the water area.

The role of periphyton depends on the characteristics of specific water bodies, and in some lakes periphyton can create up to 70% of the total primary production. The rate of photosynthesis of periphyton algae in different water bodies varies over a wide range (from Function..., 1980).

The production of periphyton algae can be significant in the littoral zone of some lakes, in certain sections of rivers and streams, especially in their upper reaches, where periphyton algae may be the only primary producers.

Some information about the values ​​of primary ecosystem production in lotic ecosystems suggests that primary production in them is lower than in limnic ecosystems (Table 6).

Table 6

Values ​​of primary production (P re, gO 2 /m 2 day) in lakes and rivers

Analysis of data for 134 reservoirs of different latitudes and continents, which were discussed in the previous chapter, made it possible to show that the primary production of plankton in reservoirs (P p, kcal/m 2 year) increases as the variability of water temperature increases throughout the year or during the open period. water (t o). It is interesting that in aquatic animals a number of production indicators are higher at variable water temperatures (Galkovskaya, Sushchenya, 1978). The studied reservoirs of different latitudes and continents form four groups, within each of which a general pattern can be traced: an increase in primary production is accompanied by an increase in temperature changes (Fig. 22), which for each of the groups can be described by equations of a power function:

Group I: Р р = 4.56t o 1.71, R 2 = 0.64, (26)

Group II: P p = 252.2 * t o 0.739, R 2 = 0.68 (27)

Group III: P p = 3995*t o 0.14, R 2 = 0.76 (28)

IY-group: Р р = 5146.6*t o 0.25, R 2 = 0.9. (29)

Each of the groups of water bodies can be characterized by the average level of primary production (P p), the limits of temperature change (t o C), and geographic location. These and other characteristics are shown in Table 7.

At the same time, the lakes of Iceland (65° and 64°N) were not included in the II group of reservoirs, since the water temperature in them differed from the usual for reservoirs at these latitudes. Reservoirs were included: in the I group of reservoirs - 4, in the II group - 4, in the III group - 2, in the IV group - 1. The minimum recorded Pp value noted in the Antarctic Lake Superior (0.58 gC/m2 year, Kaup, 1992) was not taken into account.

Table 7.

Some characteristics of reservoirs of different groups

Note: 1. When calculating the average latitude of a place, group I does not include Japanese lakes (Yunono and Tatsu-kuma 36 o N), located at an altitude of about 2000 m sea level, other designations in the text.

From the data in Table 7 it is clear that, as one would expect, the productivity of reservoirs increases in the direction from the Arctic to the tropical.

To quantify the average level of productivity, using equations (26-29), we calculate for each group the average rate of change in productivity when the temperature changes by 1 o C. For this purpose, we determine the first derivative for each of the equations, and then, taking a certain integral over the range temperature changes for each group, we will assign it to this range. As a result, for each group of water bodies we obtain a certain average rate of change in the primary production of plankton, i.e. productivity of the reservoir, when t o changes by 1 o C.

For example, for the 1st group (26) the first derivative is:

dР r / d t o = 7.94* t 0.71 (30)

The average rate of change in the primary production of plankton (U, kcal/ o C) in the range t o =t o 1 - t o 2 =1.5 o - 22 o C is equal to:

U = [dP p /dt)dt/(t 2 - t 1) = 44.1 kcal/ o C.

The U values ​​calculated in a similar way for other groups of studied water bodies are given in Table 7.

The production capabilities of reservoirs, in addition to light and temperature conditions, are also determined by the content and ratio of biogenic elements in the water. In this case, the N:P ratio reflects the source of nutrients. It is high in oligotrophic lakes, because they receive nutrients from undisturbed or slightly disturbed watersheds, which are characterized to a greater extent by nitrogen export; mesotrophic and eutrophic reservoirs receive a different mixture of natural sources, which reduces the ratio between nitrogen and phosphorus; the amounts of nitrogen and phosphorus obtained from the catchment area of ​​eutrophic lakes are close in properties to those in wastewater (Downing, McCauley, 1992).

Data analysis table. 7 showed that the rate of change in productivity (U) with a change in water temperature by 1 o C increases from north to south and reaches its greatest value (311.7 kcal/ o C) in the ecosystems of tropical water bodies.

The highest rate of increase in energy in primary production observed in the ecosystems of subtropical and tropical water bodies is due to little changing environmental conditions, in particular high water temperatures, the predominance of nitrogen content in water, which is most likely associated with the characteristics of the soils in the catchment and a higher rate of phosphorus turnover in such ecosystems. Indirect confirmation of this can be the ratio of nitrogen and phosphorus in precipitation falling at different latitudes (from Ecosystems of World, 1984):

about northern latitude 0 45 50 68 75

N: P 96 26.7 19.1 22.5 18

The general increase in the primary production of plankton in water bodies from high latitudes to low latitudes was noticed when analyzing the results of the MBP, presenting such a relationship in the form of a straight line with an increasing scatter of data at low latitudes (Brylinsky and Mann, 1973). Later V.V. Bouillon (1994) was the first to present a curve for the decrease in maximum values ​​of primary production at latitudes from 40° to 80° N. The curve shown in Fig. 23 encircles the highest values ​​of primary production in reservoirs located from 0 o to 75 o N, as well as in some lakes from 0.5 o to 38 o S. on a large number of studied water bodies, describes changes in the primary production of plankton in the ecosystems of water bodies of different geographical locations. At the same time, the greatest scatter of data was also noted for reservoirs located at latitudes close to 10°N.

Another important functional characteristic of an ecosystem is the amount of energy dissipated by all organisms in metabolic processes, which can be calculated as their energy expenditure on metabolic processes (R e). Earlier (Wetzel et al., 1972; Alimov, 1987) the concept of production was proposed ecosystems (P e). Ecosystem production is considered as the difference between the primary production of the ecosystem (P re) and the costs for the exchange of all hydrobionts of the ecosystem (P e = P re - R e).

The relationship between the production of an ecosystem (P e, kcal/m2 year) and the biomass of all hydrobionts in it over the same period of time (B e, kcal/m2) can be presented in the form of power equations:

Only the primary production of plankton is taken into account (Fig. 24):

P e = 2.073*B e 0.876, R 2 = 0.761, (31)

the primary production of plankton and macrophytes is taken into account (Fig. 25):

P e = 5.764*B e 0.718, R 2 = 0.748 (31a)

(P/B) e = 2.073*B e –0.133 and (P/B) e = 5.764*B e –0.282.

Taking into account the limits of changes in B e in the studied reservoirs from 83 to 2139 in (31) and from 30 to 6616 kcal/m 2 in (31a), we find that in the first case the coefficients (P/B) e change from 1.152 to 0.748, in the second – from 2.203 to 0.482, their average values ​​are 0.952 and 1.346 year –1, respectively. Consequently, the average value of this coefficient, taking into account only the primary production of plankton, does not differ from unity, i.e. The production of plankton algae in water bodies turns over in a year.

From the above it follows that the rate of biomass turnover in ecosystems decreases with increasing biomass in the ecosystem and it is lower in cases where only the primary production of plankton is taken into account in calculations of ecosystem production.

It must be emphasized that equations (31 and 31a) are calculated on the basis of annual average data for different reservoirs, and they cannot naturally be extended to seasonal or interannual changes in primary production in the same reservoir.

An important indicator of the functioning of an ecosystem can be the ratio of the total expenditure on the exchange of hydrobionts to their total biomass (R/B) e - the Schrödinger ratio. It serves as a measure of the ecological turnover of energy and is considered as the ratio of energy costs for maintaining life to the energy contained in the structure, or a measure of thermodynamic order - the larger the biomass, the greater the costs of maintaining it.

Analysis of data for reservoirs that were used to calculate the above equations did not show any pattern of changes in the ratio (R/B) e with changes in the productivity of reservoirs (Table 8). With a probability of 0.05, the average value of this ratio is in the range 6.1 - 2.99. In reservoirs of different types and different productivity, energy expenditure on metabolic processes in aquatic organisms is on average 4 times higher than their biomass.

Table 8

Values ​​of the ratio (R/B) e in reservoirs of different productivity

at P e  0

In most of the studied reservoirs, the difference between the energy contained in the primary production of the ecosystem and dissipated in the metabolic processes of hydrobionts is negative. For such ecosystems, the concept of ecosystem production is naturally not applicable. The value of the ratio (R/B) e in the ecosystems of such reservoirs, differing in productivity, also changes irregularly (Table 9).

The average value of this ratio in such ecosystems is 12.86 (with a probability of 0.05 does not exceed the limits of 6.5 - 19.22) and exceeds by 3.4 the value of this ratio for water bodies with P e >0. Since it is impossible to imagine a body of water in which allochthonous organic substances would not participate in the biotic flows of the ecosystem, it can be assumed, as a first approximation, that for some body of water with characteristics average for the ecosystem, the Schrödinger ratio can be taken equal to (3.43 + 12.86)/2 = 8.15 .

Table 9.

The value of the ratio (R/B) e in reservoirs of different productivity

at R e< 0

Thus, the energy costs for maintaining the structure in ecosystems of water bodies that exist mainly due to the influx of external energy are much higher than in those that can exist only due to their production capabilities. Consequently, the existence of such ecosystems is possible only if significant amounts of energy are supplied from outside. This may simply be the supply of allochthonous organic substances from the catchment area, or the supply of nutrients leading to eutrophication, or the supply of organic pollutants that also contribute to eutrophication, etc.

Relationship between structural and functional characteristics

There is no doubt that the structure and functioning of ecosystems and their components should be in a very close connection, because they reflect the basic properties of the object. As functional characteristics of communities of organisms and ecosystems, productivity, biomass turnover rate, amount of dissipated energy, the ratio between production and dissipated energy, or the Schrödinger ratio can be used. The ratio of production and dissipated energy shows the relationship between the energy exiting the system and the energy dissipated by organisms in metabolic processes in the form of heat. At the same time, the production of animal communities takes into account the production of predatory and non-predatory animals and the amount of food consumed by predators within the community.

Let us consider the relationship between structural and functional characteristics using the example of animal communities. The ratio of the production of animal communities (P b), which takes into account the production of predatory and non-predatory animals and the amount of food consumed by predators within the community to the expenditure of animals on metabolic processes (R b), and the diversity index as a generalized characteristic of the structural complexity of the community are inversely related to each other (Alimov , 1989):

P b /R b = *e -  H ,

where  and  are the parameters of the equation.

For communities of planktonic and benthic animals, the following values ​​of the equation parameters were obtained:

zooplankton P b /R b = 0.888*e - 0.553 H, R 2 = 0.59 (32)

zoobenthos P b /R b = 0.771* e - 0.431 H, R 2 = 0.55 (33)

Such quantitative dependencies for the two most important subsystems of reservoir ecosystems make it possible to assume with a reasonable degree of confidence that in relation to the ecosystem as a whole one should expect the same expression of the quantitative relationship between structural and functional characteristics, i.e.:

(P/R) e =  1 - e -  1 H

A quantitative expression of such a relationship for the ecosystem as a whole can be obtained, since the possibility of using the Shannon index to assess the diversity, and therefore the degree of complexity of the ecosystem has been shown (Jizhong, Shijun, 1991). It should be taken into account that the ratio of zooplankton and zoobenthos biomass increases as the productivity of water bodies increases (Alimov, 1990) and is associated with the ratio of the primary production of plankton and macrophytes. As the share of macrophytes in the primary production of a reservoir decreases, the role of zooplankton communities in relation to benthos communities increases (Vinberg, Alimov et al., 1988). This is understandable, since lakes with developed underwater vegetation are rich in detritus, which can be actively consumed by benthic animals. In most reservoirs, the development of the detrital trophic chain is due to the significant supply of allochthonous organic substances, which provides good conditions for the development of communities of benthic animals.

Using the Shannon index to assess the complexity of an ecosystem as a whole, calculated taking into account the abundance of specific species, is hardly possible, since determining the abundance of specific species is almost impossible for bacterial communities and is difficult in relation to plankton and especially periphyton algae. Therefore, in relation to the ecosystem, it is probably more reliable to calculate the value of this index taking into account the biomass of individual groups of aquatic organisms:

H =  (B i /B)*log 2 (B i /B).

To calculate the diversity indices and ratio (P/R) e, the most reliable and detailed biotic balances were used, compiled for the ecosystems of the Naroch lakes in 1972 and 1985, Lake Shchuchye (1981, 1982), Lake. Red, Icelandic lake. Thingvallavatn (Ecology of oligotrophic ..., 1992). At the same time, biotic balances for these lakes were selected only for those years of observations when P e >0. The results obtained are shown in Fig. 26 and they can be approximated by the equation:

(P/R) e = 1.066*e - 2.048H, R 2 = 0.496. (34)

The values ​​of (P/B) e - coefficients, as shown (Fig. 25), do not depend on the productivity of reservoirs, but a fairly large scatter of data is observed. The deviation of the coefficient value for the ecosystem of a particular lake from the average for all studied ecosystems (K = (P/B) e - (P/B) e average) is associated, with a sufficient degree of reliability, with the degree of complexity of the structure of ecosystems (Fig. 27):

K = 0.902*N - 0.778. R2 = 0.561.

Thus, as one would expect, the structural and functional characteristics of communities of aquatic organisms and ecosystems are interconnected, and this relationship can be represented in the form of equations of an exponential function: as the structure of communities of aquatic organisms and ecosystems becomes more complex, the share of dissipated energy in the form of heat increases in relation to energy contained in the products of these biological systems.

Two important conclusions follow from the above. Firstly, strict quantitative relationships between the structural and functional characteristics of biosystems give reason to hope for obtaining quantitative relationships between the flows of energy and information in aquatic ecosystems. Secondly, the structure of communities of organisms and ecosystems is preserved not due to the establishment of stable connections between elements (as with objects of inanimate nature), but due to the constant expenditure of energy to maintain the orderliness and reproduction of the elements of the system, their structures and the structures of organisms.

The state of aquatic communities and ecosystems can be described using structural and functional characteristics. A change in the structure of the system associated, for example, with the disappearance of certain species, a change in trophic relationships causes a change in the functional characteristics of the system and it passes into a new state, determined by new structural and functional characteristics.

Obtaining high production from a community of animals or ecosystems is possible only by simplifying their structure, including as a result of the exploitation of ecosystems. It is important that the production of populations is determined not only by their production potential, the amount of food resources available to animals, but also by the intensity of exploitation of the population (Alimov, Umnov, 1989) or the organization of a certain age structure of the population (Umnov, 1997).

Different degrees of exploitation of lake ecosystems lead to changes in their structural and functional characteristics. So, for example, as the load of fish on the ecosystems of fish nursery lakes increases, the share of the production of benthic animal communities in the total energy expenditure first increases and, having reached a certain maximum, begins to decrease (Fig. 28). This gives grounds to determine some optimal operating regime for such lakes. In ordinary lakes in which normal fishing is carried out, as can be seen from Fig. 26, the share of production of food items naturally decreases with increasing fish pressure. Moreover, this pattern is observed not only in relation to communities of benthic animals, but also communities of zooplankton and benthos. The ratio of production and expenditure on metabolic processes in communities of planktonic and benthic animals, as food items for fish, decreases as the average mass of fish in a reservoir increases. This means that in water bodies with larger fish, in the communities of food organisms, the share of energy in production relative to the energy dissipated in metabolic processes is lower than in water bodies with a predominance of smaller fish. If we remember that the more complex the organization of an animal community is, the greater the proportion of energy dissipated in metabolic processes in relation to the energy stored in products, we can assume that an increase in the average size of fish in a reservoir leads to a more complex structure of the communities of their food items. This phenomenon may be due to the fact that fish primarily consume large-sized animals and thereby reduce their dominance in animal communities. This confirms the idea that fish contribute to the maintenance of high species diversity and stabilization of energy flows in animal communities, expressed by Paine (1966).

" the Russian Academy of Sciences

UDC 574.583(28):o81 +574.55:58.035

PYRINL Inna Lopshovna

AS A FACTOR OF PHYTOPLANKTON PRODUCTIVITY IN INLAND WATER BODIES

03.00.16 - ecology

D i s e r i a c i n ||, h competition for a scientist with a degree in biological sciences in the form of a scientific report

St. Petersburg 1995

The work was carried out at the Institute of Biology of Inland Waters named after. II. D. Papashsha RAS.

Official opponents:

Doctor of Biological Sciences Lavrentieva G. M. Doctor of Biological Sciences Bulyon V. V. Doctor of Biological Sciences Raspopov I. M.

Leading institution: Institute of Ecology of the Volga Basin RAS ".....

The defense will take place “x. /" April 1995 at "hour. at a meeting of the specialized council D 200.10.01 at the Institute of Lake Science of the Russian Academy of Sciences (198199, St. Petersburg, Sevastyanova St., 9).

The dissertation in the form of a scientific report can be found in the library of the Institute of Lake Science of the Russian Academy of Sciences.

Scientific secretary of the specialized council

Candidate of Biological Sciences

M. A. Belova

Introduction

Relevance of research

In connection with the deterioration of the condition of aquatic ecosystems, research into the processes that influence the formation of the quality of natural waters, and above all the photosynthesis of plankton, due to which the reservoir is replenished with primary organic matter and oxygen, is becoming increasingly important. The most significant factor for this process, which occurs in an aquatic environment, is light. This is due to the limited access to plankton of sunlight, the main part of which is absorbed and scattered by water and substances contained in neii and does not reach the photosensitizing cells. In addition, the spectral composition of penetrating radiation changes in water - red and blue rays, primarily used in photosynthesis, are most strongly retained, while green rays are more fully transmitted. As a result, planktonic phytocenoses, having an advantage over terrestrial ones in terms of carbonate and water compounds necessary for photosynthesis, mineral nutrition elements and a fairly stable ambient temperature, are at a disadvantage from the energy source side. And if on the surface of the Earth, which receives relatively little sunlight weakened by the air, plants do not lack light energy, and their photosynthesis is limited by other factors, then under water this process is most limited by light.

In the theory of photosynthetic productivity of vegetation, developed by researchers of terrestrial phytocenoses, great importance is attached to the energy of solar radiation as a factor in crop formation (Nichiporovich 1956, 1908). Hydrobiologists, when assessing the primary production of aquatic ecosystems, turn to this factor relatively rarely, especially when working on fresh water bodies, which, however, are most in need of this kind of research due to the great diversity in hydrooptical terms. Therefore) special studies of the light factor of underwater photosynthesis, begun on lakes back in the 30s (Schomer, J934; Schomer, Juday, ¡935: Manning, Juday, 1941,) and picked up in the 50-80s (Talling, ¡957 , 1971, 1982; Tilzer, Schwarz, 1976; Tilzer, ¡984; Ganf, 1975; Jewson, 1976, 1977; Kirk, 1977, 1979 - cited in; Kirk, 1983; Roemer, Hoagland, 1979 cited in: Kirk , 1983; Megard et a! Moreover, if we compare it with the study of the biogenic factor of phytoplankton productivity, towards which limnological studies of the last period have deviated due to the problem of eutrophication of water bodies.

The study of light as a factor in underwater photosynthesis is inextricably linked with the study of phytoplankton pigments that capture light energy. The main one is chlorophyll “a”, being a specific substance of all photosynthesising plants and regions.

giving unique spectral properties, it makes it possible to quantify the biomass of algae without separating them from the rest of the plankton. As a direct participant in the process of photosynthesis, it can simultaneously serve as an indicator of the assimilation activity of phytoplankton. Other pigments, many of which are unique to algae, are important for understanding the ecology of underwater photosynthesis under conditions of depth-varying light.

The idea of ​​using chlorophyll in determining the biomass of photosynthetic plankton (Vinberg, 1954, 1960) turned out to be so fruitful that it served as the basis for the development of extensive research on the study of this pigment in various types of water bodies with the development of special methods of analysis, including directly in water in a continuous mode and remotely. The definition of chlorophyll has been included in most hydrobiological works, where it is considered as an indicator of the productivity and quality of natural waters, and has become an integral part of the environmental “monitoring of water bodies. The surge of interest in this pigment in modern hydrobiology turned out to be no less than about 100 years ago, when it was discovered role in plant photosynthesis. However, studies of the specific properties of chlorophyll, which ensures the absorption of solar energy by plankton, as well as the role of other pigments in photosynthesis under underwater light, especially in fresh water bodies, remain few (Tilzer, 1983; Ganf, et al., 1991) -.

Meanwhile, the parameters characterizing the relationship between photosynthesis of planktonic algae and the energy of solar radiation and chlorophyll underlie widespread computational methods for determining and mathematical modeling of primary phytoplankton production. It is important to know the values ​​of these parameters that are most adequate to a specific natural environment. Oceanologists are conducting very thorough work in this direction (Platt et al., 1980, 1990; and others), including on the basis of natural experiments (Koblenz-Mishke, 1980; Koblenz-Mishke et al., 1985; 1987). In freshwater bodies of water, such studies are less developed and the parameters necessary for modeling underwater photosynthesis are found mainly theoretically or from literary sources (StraSkraba, Gnauck, 1985).

Purpose and objectives of research

The main chain consisted of identifying the relationship between underwater light conditions and the content of phytoplankton pigments during photosynthesis and the formation of primary production in freshwater ecosystems.

For this purpose, the following specific tasks were set: (1) to study the patterns of entry and penetration of solar radiation energy of the general spectrum and photosynthetically active region in optically different fresh water bodies, taking into account the influence of solution

loose colored substances, general suspension and phytoplankton cells; (2) determine the content of chlorophyll as an indicator of photosynthesising biomass, its ratio with other phytoplankton pigments, study the patterns of their spatial, seasonal and interannual changes, evaluate the differences associated with the trophic state of the studied water bodies; (3) determine the level of primary production of phytoplankton and the efficiency of their utilization of solar energy in comparison with the light conditions and the amount of chlorophyll; (4) assess the role of solar energy entering the Earth in interannual fluctuations in phytoplankton productivity and eutrophication of the reservoir; (5) to study the light dependence of photosynthesis of phytoplankton with a diverse set of pigments in a natural environment and the possibility of using them to model primary production.

Protected provisions

I. The amount of light energy available to phytoplankton and the chlorophyll that captures it determines the level of primary production of water bodies. 2. With the relatively simple architectonics of planktonic phytopoiesis, the patterns of penetration of intensified sunlight during the process of photosynthesis and into a reservoir are quite easily described mathematically. 3. This opens up prospects for the development of calculation methods for assessing the primary production of phytoplankton based on instrumentally measured characteristics.

Scientific research

1. Using original equipment, the first measurements of the energy of underwater photosynthetically active radiation were made in a large area of ​​freshwater reservoirs (Volga reservoirs, lakes Pleshcheezo, Onega). The patterns of its penetration in optically different types of waters, in latitudinal and seasonal aspects, including the under-ice period, were studied, with an assessment of the share in the total solar spectrum. A deviation of the course of radiation in depth from that described by the classical Bouguer law was revealed, characteristic of the spectrally complex flux of solar rays in natural waters and a parameter was found to compensate for this deviation in a mathematical way.The contribution of phytoplankton relative to other suspended matter in the greening of penetrating radiation was determined.

2. For the first time, the content of phytoplankton pigments was determined in reservoirs and lakes of the Volga basin, Ladoga and Onega measures, tundra Kharbey lakes, river. Yenisei with an assessment of the proportion of ch.chozophylla "a" in the amount of its derivatives and with other chlorophylls, as well as the ratio of the total amount of green and yellow pigments." The patterns of their spatial distribution, seasonal and long-term variability were studied. The first data on specific

4. During research in the Rybinsk Reservoir, one of the longest series of long-term observations in the world (27 years) of chlorophyll content was obtained. The connection between its interannual fluctuations and synoptic features of different years is shown. A tendency for an increase in the level of pigment concentrations has been identified, indicating eutrophication of the reservoir, and the role of the energy of solar radiation entering the Earth in this process.

5. A number of reservoirs (certain areas of V. Olga before regulation, the Ivankovskoe reservoir, the North Dvina and Kharbey lakes, Lake Pleshcheyevo, Lake Ladoga) were studied for the first time in relation to the primary production of phytoplankton.

6. In the studied reservoirs, the efficiency of solar radiation energy utilization by phytoplankton and its relationship with light conditions and chlorophyll content were assessed for the first time.

7. Based on original experiments in natural settings, new data on the light dependence of photosynthesis of ecologically and taxonomically diverse phytoplankton were obtained. An analytical representation of this dependence is given.

8. Several new methodological developments have been carried out that have found application in the study of indicators of primary production of phytoplankton: (1) equipment for measuring underwater photosynthetically active radiation was designed and a simple method was proposed for calibrating it in units of irradiance based on actinometric methods; (2) spectrophotometric analysis of phytoplankton pigments in the total extract was introduced into the practice of hydrobiological research in the country; (3) a calculation method has been developed for determining the primary production of phytoplankton based on the intensity of the input. reservoir solar radiation and light dependence of underwater photosynthesis; (4) the procedure for calculating average phytoplankton characteristics for a reservoir and seasonal period has been improved; (5) original algorithms have been developed for calculating measurement errors and averaging phytoplankton productivity indicators using the method of assessing indirect errors, common in exact disciplines,

Practical value

Since the photosynthetic activity of phytoplankton is associated with the enrichment of water bodies with organic matter and oxygen, the studies carried out within the framework of this work were part of a number of projects aimed at assessing the quality of natural waters in their natural state and under various types of anthropogenic influence. This is (1) work proposed by the Government Committee on Science and Technology (GKNT) to identify the role of shallow waters in shaping the water quality of Rybinsk and Ivankovsky

reservoirs (1971 - 1973, report in 1973), according to the assessment of the ecological state of the drinking Ivankovo ​​reservoir, including after the commissioning of the Konakovo State District Power Plant (1970 - 1974, report in 1975), and reservoirs of the Volga- the Baltic system, including the Rybinsk reservoir, in connection with the problem of redistribution of river flow (1976 - 1985, report in 1980 and 1985); (2) aerospace experiments in the Rybinsk Reservoir with the aim of developing remote methods for monitoring the productivity of the reservoir based on phytoplankton pigments (1986 - 1990, report in 1990); (3) work carried out on the instructions of regional administrative bodies and practical organizations, such as environmental monitoring of the lake. Pleshcheev (1986 - 1992, reports in 1986, 1990 and 1992); assessment of the consequences of work on removing sand and gravel mixture from the ground for the biota of the reservoir - the Kuibyshev Reservoir (1990 - 1991, report in 1991); (4) work under an agreement on creative cooperation with the Krasnoyarsk State University on the study of chlorophyll in water bodies, aimed at disseminating this method in the practice of environmental monitoring of water bodies (1986 -1987, report in 1987); (5) work within the framework of the environmental program “Man and Bnoefer” (project No. 5) to identify factors influencing the level of primary production in reservoirs (1981 - 1990 with annual reports, as well as consolidated ones in 1986, 1988 and 1991).

Approbation of work

The results and main provisions of the work were presented at the first meeting on the scientific production of reservoirs (Minsk, 1960: at the all-Union meeting on the issue of the role of green algae in other reservoirs of the USSR (Korok, 1960*: on 1. P, Sh. VI All-Union Limnological Meetings on Orb and Energy and Lake Reservoirs (Lisgvenichnoye-on-Bankale, |"64, 196"-). 1973, 1985); on I (Moscow, !%5] , I (Kshshshev, 197I.). V !ol! from i. 1986) a.ezlnkh VGBO: at 1 (Tolyatti. 1968) and II (Kor. ¡974 ¡.; conferences on and ¡studies of reservoirs Volga basin; on the joint integrated use of reservoirs (Kiev, 1997); at the nervous symposium on the hydrology and biology of reservoirs heated under thermal power plants (Eorok, 197!): GTA TU (Kiev, 1972). ) and XI! (Lnstvenichnoye-ia-Bankale, 1984) All-Union" meetings on actinometry; at the II All-Union Symposium on the problem of eptrophinous water bodies (Zvesh!gorod, 1977); at the II All-Union Conference "Problems of Ecology of the Baikal Region" (Irkutsk , 1982); at a meeting on the problems of biological productivity, rational use and protection of water bodies in the Vologda region (Vologda, 1978); at the All-Union Scientific Meeting "Natural Resources of the Large Lakes of the USSR" (Leningrad, 1982); at a regional meeting on the problems of protection and rational use of internal

regional waters of the Center and North of the Russian Plain (Yaroslavl, 1984); at the I and I International Meetings on the Problems of Aerospace Sounding of Inland Waters (Leningrad, 1987,1988); at the All-Union school-seminar "Quantitative methods in hydrobiology" (Borok, 1988); at the I Vereshchagin Baikal International Conference (Listvenichnoe-on-Baikal, 1989); at methodological meetings on the study of primary production of plankton in inland water bodies (Borok, 1989) and assessment of phytoplankton productivity (Irkutsk, 1992); at a meeting of the Freshwater Biological Association of Great Britain (Windermere, 1990); at the All-Russian scientific conference dedicated to the 300th anniversary of the Russian fleet (Pereslavl-Zalessky, 1992); at the conference on environmental problems in the study of large rivers (Tolyatti, 1993); at a meeting on long-term hydrobiological observations on inland waters (St. Petersburg, 1994); as well as at seminars and scientific meetings at the place of work at the Institute of Biology of Inland Waters of the Russian Academy of Sciences.

Publications

The research results are presented in 15 sections of 10 collective monographs and in 65 journal and other articles. Before defending his PhD thesis, 10 articles were published on this topic.

I. Materials and research objects

The work is based on the results of studies of light conditions, pigment content and intensity of photosynthesis of phytoplankton in the Volga reservoirs and adjacent reservoirs, in the tundra Kharbey lakes, carried out during the entire growing season (Ivankovskoye reservoir - 1958, 1970 - 1971, 1973 - 1974; Rybinsk reservoir - 1958, 1969-1973; Kuibyshev reservoir - 1958; Lake Beloe 1976-1977; Lake Pleshcheyevo - 1983-1985; Kharbey lakes 1969) or in route surveys in certain seasonal periods (Volga river - 1957, 1960; reservoirs of the Volga-Baltic and North Dvina waterways, including Ladoga and Onega lakes - 1973; Sheksna and Upper Volga reservoirs - 1979). Observations of phytoplankton pigments in the Ivankovsky conservation area continued in 1977-1978, in lake. Pleshcheyevo - until 1991, in the Rybinsk Reservoir they moved into continuous long-term research, which is ongoing to the present day. Detailed studies of phytoplankton pigments were carried out at the gistatory of Lake Onega (1967-1968) and the river. Yenisei (1984-1985). In the Rybinsk Reservoir, small-scale changes in pigment content were studied as part of an aerospace experiment to develop a technique for remote optical sensing of water bodies

in the water area and in time (1986-1988). In the Rybinsk (1971-1972) and Ivankovsky (1973-1974) reservoirs, a series of works was carried out in the shallow zone to assess its role in the enrichment of the entire reservoir with primary organic matter. In the Rybinsk reservoir and lake. Pleshcheyevo carried out winter observations of the development of phytoplankton under the conditions of the light regime of the subglacial period. During route expeditions to the Volga and Sheksninsky reservoirs (i960, 1979), in the Rybinsk reservoir (1970-1971, 1987), in lakes Onega (1968) and Pleshcheyevo (1983-1984), special work was carried out on studying solar radiation penetrating into water and light dependencies of underwater photosynthesis. Photosynthesis activity was studied in the Ivankovo ​​Reservoir. plankton under conditions of elevated temperature (1970-1971), created under the influence of waste water from a thermal power plant, in the Kuibyshev Reservoir - the effect on phytoplankton of mineral suspensions entering the reservoir during dredging and other works. related to soil removal (1990-1991).

Some materials were obtained jointly with employees of the Institute of Biology of Inland Waters (J1.B. Morokhovets, O.I. Feoktistova, N.P. Mokeeva, A.L. Ilyinsky, V.A. Elizarova, E.I. Naumova, V.G. Devyatkin, L.E. Sigareva, E.L. Bashkatovon, N.M. Mnneeva, L.G. Korneva, V.L. Sklyarenko, A.N. Dzyuban, E.G. Dobrynin, M.M. Smetanin ) and other scientific institutions (V.A. Rutkovskaya, I.I. Nikolaev, M.V. Getsen, T.I. Letanskaya, I.S. Trifonova, T.N. Pokatilova, A.D. Prnymachenko), in co-authors with whom the relevant publications were written or their independent articles containing the necessary data were used in this work. T.P. has always participated in the collection and processing of materials for many years. Zaiknna is a senior laboratory assistant at the algology laboratory of the Institute of Inland Water Biology. To all of them, as well as to the staff of the computer center and experimental workshops, technical staff of the Institute of Biology of Inland Waters, students of Moyek, Vsky, St. Petersburg, Nizhny Novgorod, Yaroslavl, Perm and Kazakh universities, who had internships at the Institute, the author expresses deep gratitude and gratitude for their help in conducting research.

II. Research methods

Studying the characteristics of the light mode

The study of the conditions of the light regime as a factor in the primary production of phytoplankton is associated with significant methodological difficulties due to the fact that the radiant energy of the Sun passing through changes not only quantitatively, but also qualitatively. The spectral composition and angular

characteristics of penetrating radiation, the intensity of radiation entering the water continuously changes depending on the height of the Sun above the horizon and cloud conditions. Ideally, a device is needed that could record both depth-varying and photosynthetically active radiation summed up over time - PAR (k = 380-710 nm), expressed in units of irradiance, since such devices did not exist (Report.. ... , 1965, 1974). The device consists of a set of sensors that capture radiation from the hemisphere - irradiance (subject to the cosine law), one of which is sensitive in the wavelength range covering PAR (380-800 nm), the others - in narrower sections of this spectrum region (480-800, 600-800, 680-800 nm). The spectral sensitivity of the sensors is achieved by combining a vacuum photocell TsV-3 with light filters SZS-14 + BS-8 - covering the entire wavelength range of 380-800 nm and SZS-14 + ZhS-17, SZS-14 + KS-10, SZS-14 + KS-19 - for the rest of its gradually tapering parts, respectively. The recording device automatically sums up the radiation energy over time.

The calibration of the device in units of irradiance, developed on the basis of actinometer methods (Berezkin, 1932), is carried out according to direct solar radiation, measured by an actinometer with appropriate light filters. Direct rays are separated from the total radiation flow arriving at the sensor using a tube mounted on it, which is similar in design to the actinometer tube (Pyrina, 1965, 1993).

Many years of experience in using an underwater photointegrator, including in comparison with standard actinometric devices, have shown the reliability of its operation in field conditions with a sufficiently high accuracy of the measurement results of both the integral PAR flux and narrowed sections of this spectral region. The first samples made about 30 years ago are still working. Moreover, serial devices for underwater measurements of phased arrays such as Li-Cor and QSP (USA), QSM (Sweden), currently existing (Jewson et al., 1984), as well as single models in our country (Semenchenko et al. , 1971; Czech Republic, 1987), are still inaccessible.

Almost all experiments to determine the primary production of phytoplankton were measured by measurements of the energy integrated over the PAR spectrum entering the reservoir; for this purpose, a photointegrator sensor was installed on the upper part of the ship’s superstructure or on an elevation open to the Sun on the shore, recording the influx of radiation during the exposure time.

When studying the conditions of the light regime in a reservoir, measurements were carried out in several parts of the PAR spectrum, using the entire set of underwater photointegrator sensors, differing in spectral sensitivity. The sensors were launched into the reservoir suspended on a float, together with which they were moved away from the vessel 10-15 m, less often on a winch equipped with an elongated extension in the direction of the Sun. Some of these measurements were accompanied by observations of the penetration of solar radiation of the general spectrum, which were carried out in 1960 by V.A. Rutkovskaya (1962, 1965) and in 1979 by T.N. Pokatilova (1984, ¡993). Onn used the Yu.D. pyranometer. Yashpievsky (1957), adapted for underwater measurements, which was immersed in a reservoir with a winch with removal. All measurements of penetrating radiation were carried out at 10-12 horizons to a depth until the threshold sensitivity of the instruments made it possible to obtain reliable readings.

In those cases where measurements of solar radiation were used to conduct experiments on the light dependence of phytoplankton, flasks with test samples were mounted on the device, and such an installation was exposed in the reservoir during the entire exposure. These installations were equipped with the number of horizons for determining photosynthesis, planned depending on water transparency. In this way, it was possible to quite fully register the radiation energy entering the sample and obtain data that was most adequate to the light dependences of photosynthesis of natural plankton.

If necessary, have data on underwater light conditions

for a large number of stations, they resorted to a calculation method for determining penetrating radiation based on its arrival at time t; Transparency oxen I bake Sekhki, using the proposed F.E., Api c D.I. Tolstyakov (1969) formula or, later, a refined pari chit (Pyrina, 1989).

izanmotrans.chod from the energy of incoming radiation of the general spectrum:: (l. = 380-710 im) or recorded by a photointegrator (l = 3íW-300 i, i) and vice versa was carried out using empirical coefficients (Pyrnna, 1985), selected by pavnenmoesh or relationships about personality, and in clear weather - also about the height of the Sun.

Data on phytoplankton ingmengs - the total content of chlorophylls, dating back to 1958 (Pyrpna, I960), were obtained by the photometric method (Vinberg, Sivko, 1953) with calibration using an extract from cultures of diatoms and blue-green algae, where the initial concentration of chlorophylls was measured spectrophotometrically based on specific extinction coefficient 95 l/g cm (Koski Smith, 1948). Since 1960, a spectrophotometric method has been used to determine individual forms of chlorophyll and carotnoids in the total extract (Richards, Thompson, 1952). This method is

valuable then for analyzes of phytoplankton pigments for the first time in the country (Pyrnna, 1963) and simultaneously with advanced foreign research in this direction (Humphrey, 1963; Tailing, Driver, 1963), then became widespread in the study of phytoplankton pigments and, after some clarifications (Parsons, Strickland, 1963; SCOR-UNESfCO, 1966; Jeffrey, Humphrey, 1975), was recommended as standard (Lorenzen, Jeffrey, 1980; Marker et el., 1982; GOST, 1990).

Chlorophyll concentrations were calculated in 1960 using the formulas of Richards and Thompson (1952), in 1967-1976. - SCOR-UNESCO (1966), in other years - Jeffrey and Humphrey (1975). Concentrations of carotenoids were calculated in the first year using the formulas of Richards and Thompson (1952), then Parsons and Strickland (1963) for the day of diatom plankton that predominated in the studied reservoirs. The concentrations of pheopigments and, minus them, pure chlorophyll a were calculated using Lorenzen’s formulas (Lorenzen, 1967).

As is known, the formulas of Richards and Thompson (1952) used underestimated specific extinction coefficients of chlorophyll a and b, and its conditional values ​​for chlorophyll c and carotenoids, and therefore their concentrations differ from those obtained later. For chlorophyll “a” they are overestimated by 25% compared to those calculated using other formulas based on higher extinction coefficients of this pigment (88-92 l/g.cm). Data on the concentrations of chlorophyll "b" and "c" changed more as the expansion coefficients and formulas for their calculation were refined - by 150-200%. The results of calculations using different formulas for carotenoids differ even more (up to 2.5 times); due to the diversity of their composition in natural plankton, it is almost impossible to select suitable values ​​of extinction coefficients for calculating the concentrations of these pigments in the total extract. Therefore, later the proportion of carotenoids relative to chlorophyates was judged by the ratio of extinctions in the region of their greatest contribution to light absorption by the extract - Eva / (Pyrina, Sigareva, 1976), proposed for these purposes back in the late 50s (Burkholder et al., 1959) . Taking into account the noted deviations in the calculation results of different years, comparison of data on the level of phytoplankton pigments was carried out using chlorophyll “a”, as the most accurately determined. At the same time, a correction of 0.75 was introduced to the early data obtained using the Richards and Thompson formulas (Pyrina and Elizarova, 1975).

In the process of working on the method of determining phytoplankton pigments, a non-extractive method of measuring chlorophyll directly in algae cells collected on membrane filters was tested after they were clarified with immersion oil (Yentsch, 1957). The method attracted attention for its simplicity and showed satisfactory results in the analysis of lake plankton (Vinberg et al., 1961However, it turned out to be unacceptable for determining

chlorophyll deficiency in reservoirs characterized by a high content of detritus and mineral suspended matter (Pyrina and Mokeeva, 1966).

3. Determination of primary phytoplankton production

In stationary studies in small lake reservoirs (Lake Plesheevo, Kharbey Lakes), classical “in situ” experiments were carried out (Vinberg, 1934) with sampling to measure photosynthesis at the depths of their exposure - 5-7 horizons of the euphotic zone of the reservoir. On the reservoirs of the Volga cascade and adjacent reservoirs, where work was carried out from an expedition vessel, a calculation method was used to determine primary production with sample exposure to measure the initial values ​​of photosynthesis in a deck incubator simulating the conditions of the surface layer of water. At the same time, at the first stage of research, experiments were carried out according to the modified scheme of Yu.I. Sorokin (1958), which provides for measuring the intensity of photosynthesis in samples of several depths of the photonic zone of the reservoir with an empirical connection to the obtained values ​​for the attenuation of penetrating solar radiation (Pyrina, 1959(a) ), 1966). Subsequently, they limited themselves to determining the maximum value of photosynthesis along the vertical profile in the incubator (Amshs) based on the average or total sample for the euphotic zone, and its decrease in depth was assessed based on the penetration of radiation (Pyrina, 1979). The radiation energy at the depths under study was usually found in such experiments using computational methods (Are and Tolstyakov, 1969; Pyrina, 1989, 1993). If it was impossible to determine the intensity of photosynthesis, the chlorophyll method was used with an estimate of Alm from the assimilation number, which was selected from previously established values ​​in accordance with the specific conditions of the reservoir.

Experiments to study the light dependences of photosynthesis photosynthesis were carried out in a natural environment with exposure at several depths of the epphotic zone of a reservoir homogeneous"; bottom samples taken from the surface or, in the case of pronounced stratification, completely within the epilnmnon. As a rule, at the same depths throughout During the exposure, fogointegrator sensors worked, often flasks with test samples were attached to them (Pyrina, 1967, 1974).In some experiments, together with the PAR recorded by the fogointegrator at the same depths, urgent measurements of the radiation energy of the general spectrum were carried out using an underwater pyranometer and it was calculated sums during the exposure time. As a result, a series of light curves of photosynthesis were obtained, constructed relative to the total solar radiation (Pyrina, Rutkovskaya. 1976). If it was impossible to keep the instruments near the chks for a long time: one-time measurements of underwater irradiance were made with locked samples, usually at midday, at the base of the mountain? and PAR energy coming to the surface of the reservoir. continuously rs

collected on the shore or on board a ship, its arrival at the studied depths during the exposure was determined.

The intensity of photosynthesis was assessed by oxygen during daily exposure, which in stationary experiments “in situ” began in the evening, in others - as samples were taken at stations, in compliance with the basic recommendations available in the literature on this method (Alekinidr., 1973; Vollen weider et al. (1974; Pyrina, 1975,1993).

4. Mathematical processing of research results

Since, based on the research results, the levels of phytoplankton productivity were compared in different reservoirs and in different years, when it is important to have confirmation of the reliability of the emerging differences, special attention was paid to assessing the average values ​​​​from the data obtained and errors in their representativeness (Pyrina, Smetanin, 1982, 1993; Pyrina, Smetanii , Smetanina, 1993).

Determining the average values ​​for a reservoir is complicated by the fact that they relate to material of different origin - repeated measurements in one sample, samples from different depths at individual stations, different stations and sections of the reservoir, and different periods of the growing season. Therefore, averaging was carried out in several stages, at some of them, when data were averaged for water masses of different volumes or for different time intervals, the average values ​​were calculated as weighted averages.

The procedure for averaging data over the water area of ​​a reservoir included calculating the arithmetic mean based on the results of repeated measurements in one sample, then based on sample data for the same depths of different stations (or water layers), then a weighted arithmetic mean based on data from individual layers for each section and , finally, the reservoir as a whole. The last two values ​​were calculated taking into account the volumes of layers and sections of the reservoir, respectively, estimated by its level at the time of observation. In the absence of bathymetric data necessary for such assessments, it was allowed to equate the basin of the reservoir with a body with vertical walls and instead of the volumes of its sections, their area was entered into the calculations, and instead of the volumes of water layers, their thickness was entered into the calculations.

Obtaining average data for the growing season was reduced to calculating arithmetic averages for time intervals between individual observation periods, then a weighted arithmetic average for the entire period, taking into account the number of days of each interval. The growing season in the studied reservoirs was equated to an ice-free one, at the beginning and end of which the quantitative characteristics of phytoplankton were taken equal to zero. The dates of disappearance and appearance of ice in the reservoir were determined according to the Hydrometeorological Service.

Due to the fact that most of the indicators studied are not measured directly, but are calculated based on other measurements using appropriate formulas, just as they are not found

By directly calculating the average values ​​from the results obtained, it is difficult to simply determine their representativeness errors using classical methods. Therefore, we used the method of assessing indirect errors (Zajdel, 1974), in which the characteristic being studied is considered as a function of several variables, the accuracy of which; ry is predetermined, and its total error is found by “quadratic addition” of measurement errors of individual components using differential calculus and probability theory. Based on this method, original algorithms and computer programs were compiled that make it possible to quickly evaluate measurement errors and averaging the results obtained .

III. Characteristics of the light regime of the studied

aodosg.sha

Due to the large extent from north to south of the territory where the reservoirs were studied, the intensity of the total solar radiation energy arriving at their surface is different. According to average long-term data, its values ​​range from 3500 MJ/m1 year in the Kostroma region to 5000 - near Astrakhan it is 600 and 750 MJ/m1 month, respectively, at the height of summer in June (USSR Climate Reference Book, 1966). Together with However, on certain days of the summer period (July-August) the intensity of solar energy over northern reservoirs is the same !, up to "4 MDch-"./m2 "" ug pp (V-X) a yes Average n! hi"."pen Volga - up to 8 (IV-XM. The etepemg restriction pa-lazhen on ps.yerkhng.st ¡""di radiation, which Ooshama g> yygokoshi-roton zone tThomasson, 1956, is also different. However, the river was preserved. Almost mt along its length, the albedo of the water surface is characterized by the following values: 4-7% at 1K>lu.ya“other hours. 5-7% in spelled for cheap, min increased values ​​and reservoirs with a high content of p»e<и, » осоосннссгн "¡тегущих"" синсзеясмымн ыдорос mtn (Рутковская, 1962; Кирилова, 1970).

The share of PAR in the flux of radiation of the general spectrum over the water bodies of the Upper Volga basin on clear days, as is customary in hydrobiological works (VbiJenweuier et al., 1974), is 46%, but as cloudiness increases to 57% (Pyrpna, ¡935).

Observations of the distribution of total solar radiation at depth in the reservoirs of the Volga basin showed that the maximum transparency for them (up to 2 m along the Secchi disk) is 1% of the total

The amount of radiation released into the water is recorded no deeper than 2 m. Only in the Volgograd reservoir, with water transparency up to 2.4 m, such radiation values ​​were recorded at depths of 3-4 m (Rutkovskaya, 1965). In more transparent lake waters, about 1% of the radiation entering the water is observed even deeper: at 5-6 m in Lake Ladoga (Mokievsky, 1968); 6-7 m in Onega (Mokievsky, 1969; Pyrina, 1975(a)); 6-8 m in the lake. Pleshcheyevo (Pyrina, 1989(a)). An increase in the depth of radiation penetration was also noted as the height of the Sun above the horizon increased during the daytime, as well as towards the south (Rutkovskaya, 1965).

When entering water, the outermost long-wave and short-wave rays attenuate first, and only radiation close to PAR penetrates deeper than 1 meter (Rutkovskaya, 1965; Pyrina, 1965; Pokatilova, 1993). The main role in attenuating solar radiation in reservoirs is played by detritus and mineral suspension. Against this background, the absorption of light by phytoplankton - the so-called “self-shading effect” (Talling, 1960) - is weakly felt. It can be observed only in the summer when the water “blooms” with blue-greens, coinciding with a period of increased stability of the water mass, when the share of algae in the total amount of suspended particles becomes predominant (Pyrina, Rutkovskaya, Ilyinsky, 1972). And only in clear lake waters such as lakes. Pleshcheyevo, the optical influence of phytoplankton can be traced quite clearly even during the period of homothermy (Pyrina, Sigareva, Balonov, 1989).

In the turbid waters of reservoirs, increased values ​​of diffuse radiation returning from the depths are observed. According to PAR measurements in the Rybinsk Reservoir, with a transparency across the Secn disk of 0.7-1.5 m, the eye amounted to 2-10% of the radiation entering the water, while in Lake Onega - transparency of about 4 m - less than 1% (Pyrina, 1975(a) ).

Spectral measurements of penetrating PAR in the Rybinsk Reservoir and Lake Onega (Fig. 1) showed that in the surface layer of water there is a fairly large proportion of red-orange rays with wavelengths of more than 600 nm, as well as blue ones (X - 380-480 nm). However, both of them quickly fade and green rays penetrate most deeply (X = 480600 nm). In waters with a color value of more than 70 degrees on the platinum-cobalt scale, an increased decrease in the proportion of blue radiation (X = 380480 nm) absorbed by the uppermost layer of water was noted (Pyrina, 1975(a)).

Winter observations. on the penetration of PAR through the snow and snow cover, carried out in the Rybinsk Reservoir, showed that under typical conditions with a snow layer of 20 cm and ice thickness of 80 cm, no more than 0.04% of the energy of incoming radiation reaches the water (which amounted to 200-250 W/m " ), This is due to intense reflection from the snow (80%), the proportion of backscattering from the snow (3%) and radiation delayed by it (13%) is relatively small. After the snow melts, the amount of radiation penetrating under the ice increases to 18-20%,

Rice. I. Penetration of solar rays of different wavelengths into the water column of Lake Onega (a-c) and the Rybinsk Reservoir (d-f), % o g

incoming radiation energy.

1 - L = 380-800 im; 2-X-480-800 nm; 3 - L = 600-800 k\<; 4- Л = 680-80") им; вертикаль вниз - прозрачность по белому диску; цифры гмд пен ■ цветность по пяатиново-кобалътовой шкале.

and it can be traced to a 2-mega depth - 0.4%. At the same time, reproduction of phytoplankton is noted (Pyrina, 1984.1985(a)).

Taking into account the complexity of underwater PAR measurements, which require special equipment, and also the fact that after passing through a relatively small layer of water, only this part of the solar spectrum remains, we studied the patterns of attenuation of the integral radiation flux in a reservoir in order to use standard actinometric data of the Hydrometeorological Service.

When describing the course of solar radiation in depth, the classical Bouguer law is widely used, which, as is known, is not entirely legitimate, since the law is valid only in the case of monochromatic radiation. Radiation values ​​calculated using Bouguer's formula:

(where 1r and 10 are the intensity of radiation at depth r and entered* into the water, and "the indicator of vertical attenuation), deviate from the measured ones - in the upper layers of water they are overestimated, in the deep layers they are underestimated, which was noted in a number of works by SDovgy, 1977; Szumiec , 1975; Kirk, 1983).To compensate for this deviation, it was proposed to introduce into the exponent of formula (1) the parameter r to a power less than 1, in particular, equal to 0.5 (Rosenberg, 1967), and natural data (Are, Tolstyakov, 1969; Larin, 1973) confirmed the possibility of calculating penetrating radiation with this modification:

However, the application of modified formula (2) in the present studies revealed a significant overestimation of the radiation intensity calculated for the lower horizons, which must be taken into account when determining the depth of photosynthesis and its integral value in a water column under 1 m1. The study of this phenomenon has shown that the most adequate description of the course of solar radiation in depth is obtained by using formula (2) with a variable value of the exponent (u) for the parameter r,

The value of n varies depending on the color of the water and at low values ​​it is close to theoretical. For example, for the lake. Pleshcheyevo with water color on the platinum-cobalt scale of 10 degrees "=0.6, and for

Rybinsk Reservoir with a color of 50 degrees l = 0.8 (Pyrina, 1989).

Thus, the study of light conditions for underwater photosynthesis in the studied reservoirs showed a large range of penetration depths of solar radiation, varying, with intense insolation, from 2 - 5 m in the low-transparent waters of the Volga reservoirs to 7 - 12 m in lakes Onega and Pleshcheyevo. Due to the rapid attenuation of extreme short- and long-wave rays at a relatively shallow depth, lying within the upper! .5-meter layer, the penetrating radiation becomes identical in the PAR spectrum. Due to selective attenuation by water, a deviation of its depth progression from obeying the exponential law is observed, which can be compensated mathematically. “This makes it possible, with sufficient accuracy in hydrobiological work, to calculate the energy of solar irradiation necessary for photosynthesis from the intensity of solar radiation over a reservoir, including that recorded on land by the nearest actinometric station.

Determinations of phytoplankton pigments, begun in 1958 in the Ivankovo, Rybinsk and Kuibyshev reservoirs and then carried out in all studied water bodies, showed a large range of fluctuations in their concentrations (Table 1). For the main pigment - chlorophyll "a" they range from hundredths of a microgram per liter to!00 or more "calculated for the euphotic zone of the reservoir. However, each shnoloemo" is characterized by a certain level of average values ​​for the betaine season and the maximum achieved values, according to which can be used to judge the trophic association of its waters.According to this principle, the reservoirs of almost all water bodies were covered by inheritance - from the monotrophic Onega Lake to the eugrophic Ivankoch Reservoir.

Changes in chlorophyll concentrations within a reservoir are associated mainly with the seasonal dynamics of phytoplankton, during the period of mass growth of which (as a rule, in May and June ■ !iguete) their maximum values ​​are observed. ] 1a nrig^p^ of the Rybinsk Reservoir it is shown that the height and timing of these maxima at specific times depends on the hydrometeorological features of the year (Pyrina, Sigarepa, 1986). Here we traced the uro-ttagt, tsoggceggtrpcpy of chlorophyll in the sub-ice gter.tod, when no more than 0.2 µg/l was delivered. Only after the disappearance of snow and penetration of about I MJ/m2 ■ day of photosynthetically active radiation under the ice did the chlorophyll concentrations rise to 0.4 µg/l and phytoplankton vegetation began (Pyrina, 1985(a)).

Table I

Reservoirs Years, Chlorophyll, Source

months µg/l information

Ivankovskoe 1958, V-IX 12.5 Pyrina, 1966

vdhr. 0 - 2 m 1970, V-X 13.3 Elizarova, 1976

1973-1974, V-X. 26.7-31.8 Pyrina, Sigareva,

1978, V-X 14.2 Pyrina, Sigareva,

■ unpublished

Rybinskoe 1958, V-X 6.6 Pyrina, 1966

Main reach. 1969-1971, V-X 3.4 - 6.7 Elizarova, 1973,

1972-1976, V-X 6.2- 10.0 Pyrina, Sigareva,

1977-1979, V-X 6.6 - Yu.o Mineeva, Pyrina,

1980-1982, V-X 9.3-18.2 Pyrina, Mineeva,

1983-1985, V-X 15.4-19.2 Pyrina, 1991

1986-1990, V-X 9.4-13.8 Ibid.

1991-1993, V-X 12.6-.14.6 Pyrina, unpublished.

Kuibyshevskoe 1958, VI-X 7.9 Pyrina, 1966

vdhr. 0 - 3 m

White Lake. 1976-1977, V-X 3.8 -5.0 Pyrina, Mineeva and

0-2 m dr., 1981

Oz. Pleshcheyevo 1983-1985, V-X 6.2-10.0 Pyrina, Sigareva,

Balonov, 1989

Oz. B. Kharbey 1969, VII-VIH 2.0 - Elizarova, Pyri-

on, Getzen, 1976

Onega 1967-1968, 0.57 - 0.95 Pyrina, Elizarova,

lake. 0 - 5 m VII-VIIÍ Nikolaev, 1973

Lake Ladoga - 1973-1974, VIII 4.60 Pyrina, Trifo-

ro. 0 - 4, 0 - 5 m nova, 1979

R. Yenisei. 1984-1985, 4.2-7.2 Pyrina, Priyma-

0 m - bottom VWX Chenko, 1993

Note: the average values ​​for the reservoir and growing season are given, with the exception of Lakes Onega and Lake Ladoga, where data are averaged for the summer season.

Differences in chlorophyll concentrations across water bodies are less pronounced. Only areas receiving river waters enriched with nutrients, as well as shallow waters, especially isolated and weakly overgrown with macrophytes, where the content of decay is increased (Egshzarova, 1976, 1978; Elizarova, Sigareva, 1976; Elizarova, Pyrina, Getsen, 1976; Pyrina, 1978; Pyrina, Pltarova, Nikolaev, 1973; Pyrina, Priymachenko, 1993). Small-scale differences within a homogeneous water mass are relatively small and are associated mainly with the action of dynamic factors - circulation flows that determine the integral transport of phytoplankton, wind mixing and stratification of waters (Pyrina, Sigareva, Balonov, 1989; Pyrina, Mineeva, Sigareva et al. , 1993).

In most of the studied reservoirs, the products of the transformation of chlorophyll - pheopngments - were noted in significant quantities. For example, in the Rybinsk Reservoir, the amount of pheopigments cociasiiU is 20-30% of the amount with pure chlorophyll, and during the early summer minimum of phytoplankton it rises to 60-70%, especially in the lower layers of water (Pyrina, Sigareva, 1986; Pyrina, Mineeva , 1990). In Lake Pleshcheyevo at this time, the same amount of pheopigments is observed in the surface 2-meter layer (Pyrina, Sigareva, Balonov, 1989; Pyrina, 1992), which is combined with an increased abundance of herbivorous zooplankton (Stolbunova, 1989). Only during the period of maximum summer warming, which is usually associated with the “blooming” of blue-green water, is the content of pheopigments less than 10%. This coincides with the intense intake of solar radiation, which prevents the accumulation of chlorophyll-containing chlorophyll in the illuminated area due to the destructive effect of sun (Yentsch, 1965; Moreth Yenisei), 1970), as well as the preservation of the high stability of the upper layer of water, where this process occurs (Pyrina, Sigareva. 19X6 ).

Other green pigments - chlorophylls "b" and "c" - were found in much smaller quantities. The content of chlorophyll c" in south diatoms, cryptophytes and dinophytes is slightly higher (up to 30%) of the total chlorophyll than chlorophyll "b" (several percent). However, coastal, estuary and other waters are enriched with nutrients and, accordingly, green and euglenic algae - carriers of chlorophyll "b", its content can reach 10%.

Carotenoids, measured in arbitrary units, usually correspond to chlorophyll in quantitative terms. A tendency was noted for an increase in their ratio with chlorophyll, both in absolute content and in extinctive ratio, as water productivity decreases. For example, in the central part of the Rybinsk reservoir it is higher than in river reaches and coastal areas, and in the central part of this reservoir it is higher than in the Ivankovo ​​reservoir (Elizarova, 1973, ¡976; Elizarova, Sigareva. 1976; Pyrina, Sigareva

1978, 1986). It is even higher in Lake Onega, especially its deep zone, and in the tundra Kharbey lakes (Pyrina, Elizarova, Nikolaev, 1973; Elizarova, Pyrina, Getsen, 1976). The exception is the Yenisei River, which, with relatively low water productivity, is characterized by a lower level of this ratio (Pyrina, Priymachenko, 1993). When analyzing the ratio of green and yellow pigments in a seasonal aspect, an increase is observed during the early summer minimum of phytoplankton, especially during the reproduction of phytophages (Pyrina, Sigareva, Balonov, 1989) and a very strong increase in winter (Pyrina, 1985/a).

In terms of the specific content of chlorophyll "a" (usually 2-5 μg/mg) and carotenoids (1-5 μBri/mg) in the phytoplankton biomass, no significant differences are detected in the studied water bodies (Pyrina, 1963; Elizarova, 1974, 1976; Pyrina, Elizarova, 1975; Elizarova, Pyrina, Getsen, 1976; Pyrina, Priymachenko, 1993). Only an increase in the chlorophyll content was noted in the biomass of phytoplankton with a noticeable proportion of green algae, as in the cultures of these algae (Pyrina, Elizarova, 1971), as well as in the oligodominant community with a predominance of small-celled species from the genus Biriapsis (Pyrina, Sigareva, Balonov, 1989) ,

Thus, while the general patterns of seasonal and spatial dynamics of phytoplankton pigments are similar, the level of their concentrations in the studied water bodies varies widely, ranging from 1-2 μg/l on average during the growing season in the unproductive lakes Onega and Bolshaya Kharbey to 30 μg/l - in the eutrophic Ivankovsky reservoirs? However, the specific content of chlorophyll in the biomass of phytoplankton, which is similar in the set of pigments and the composition of the dominant species, is quite close. There are no traces of any peculiarities of pigment characteristics associated with light adaptation of phytoplankton from optically different reservoirs. The role of light conditions is manifested only in regulating the process of formation and accumulation of chlorophyll derivatives in the euphotic zone of a reservoir during the period of stable weather of the anticyclonic type.

V, Photosynthetic activity of phytoplankton

Based on the value of primary production of phytoplankton in a water column under 1 m2, most of the studied water bodies fall into the category of mesotrophic, although the trophy level of this type of water varies: from a level close to oligotrophic for the tundra lake B. Kharbey to bordering on eutrophic for the Rybinsk reservoir (Table 2). Only Lake Onega is classified as typically oligotrophic reservoirs, and the Ivankovskoe reservoir and the Cheboksary section are classified as typically eutrophic. The lake occupies a special place. Pleshcheyevo, for which

table 2

Average values ​​of primary production of phytoplankton in the studied water bodies during the growing season (g C/m2 day)

Ivankovskoe 1958 0.90 Pyrina, 1966

vdhr. 1970-1973 0.90 - 1.28 Pyrina. 1978

1974-1976 0.36 - 0.68 Sappo, 1981

1979-1980 0.91 - 1.35 Tarasenko, 1983.

Rybinsk Reservoir 1955 0.28 Sorokin, 1958

1958 0.54 Pyrina, 1966

1959 0.59 Romanenko, 1466

1001-1905 0.10-0.19 Romanenko, 1985

1966-1971 0.21-0.48 Same

1972-1973 0.69 - 0.72 Same

1974-1980 0.18-0.35 Same

1981 0.83 Same

1982 0.52 Mineeva, 1990

Gorkovskoe 1956 0.41 Sorokin, Rozanova,

vdhr. Sokolova, 1959

1967 0.76 Tarasova, 1973

1972 0.89 Tarasova. 1977

1974-1979 0.31 - 0.85 Shmelev, Subbopsha. 1983

R. Volga for part - 1966 2.25 Tarasova, 1970

tke Cheboksary-

Kuibyshevskoe 1957 0.66 Salmanov, Sorokin,

1958 0.83 Pyrina, 1966

1965-1966 0.37 - 0.72 Ivatin, 1968, 1970

1967-1971 0.32 - 0.56 Ivatin, 1974, 1983

Saratov 1971-1973 0.32-0.50 Dzyuban, 1975, 1976,

Volgograd 1965-1968 0.30 - 0.63 Dalechina, 1971, 1976

vdhr. 1969-1974 0.33 -0.64 Dalechina, Gerasimo -

1975 1.50 Same

Continuation of Table 2

Reservoirs Years Primary Source

research production information

White Lake 1976-1977 0.21 -0.31 Pyrina, Mineeva, and

Oz. Pleshcheyevo 1983-1984 1.36- 1.86 Pyrina, Sigareva,

Dzyuban,)989

Lake Onega 1966, VII 0.05 - 0.20 Sorokin, Fedorov,

Lake Ladoga 1973-1974, 0.32-0.60 Pyrina, Trifonova,

Oz. B, Kharbey. 1968-1969 0.14-0.26 Pyrina, Getsen,

Vainshteii, 1976,

R. Yenisei 1984 0.86 Prinmachenko, 1993

Note: when converting to carbon, the oxygen method data were multiplied by 0.375; for Lakes Onega and Ladoga, maximum values ​​are given for the open part

The highest values ​​of primary production were obtained (in summer up to! 3 g Og/m2 day), despite the fact that the chlorophyll content and the intensity of photosynthesis per unit volume of water are relatively low here.

The seasonal course of plankton photosynthesis in the studied water bodies is characterized by general patterns and is determined mainly by changes in the abundance of algae. In lakes and lake-like reservoirs, such as Rybinsk and Kuibyshev, where the periodicity of changes in the dominant groups of algae is clearly visible, spring and summer peaks are observed, although the first of them is usually less pronounced due to the limiting influence of low temperatures (Pyrina, 1966; Pyrina, Mineeva, and al., 1981; Pyrina, Sigareva, Dzyuban, 1989), In river-type reservoirs with increased flow, for example, Ivankovsky, where diatoms prevail throughout the growing season, the seasonal course of photosynthesis is more smoothed. However, even here in mid-summer its maximum values ​​are observed (Pyrina, 1978). In shallow waters, while the general nature of seasonal dynamics is similar to the deep-water zone, a shift in photosynthesis peaks to earlier dates was noted (Pyrina, Bashkatova, Sigareva, 1976). In winter, judging by individual observations in the Rybinsk Reservoir (Romanenko, 1971), photosynthesis is extremely weak due to the lack of light under the snow and ice cover (Pyrina, 1982, 1985(a)).

Spatial differences in primary production are closely related to the degree of phytoplankton development (chlorophyll content). However, this is clearly visible only in terms of the intensity of photosynthesis per unit volume of water. For its integral values, calculated per unit area of ​​the reservoir, this pattern is violated, which is one way or another connected with the conditions of the light regime. Thus, in shallow waters rich in phytoplankton with depths less than the euphotic zone, the primary production of iodine 1m: is relatively small due to the limitation photosensitizing layer at the bottom (Pyrina, Bashkatova, Sigareva, 1976; Pyrina, 1978; Pyrina, Sigareva, Dzyuban, IW).In strongly “blooming” blue-green waters, the “self-shading effect” limits the access of light energy to the phytoplankton of the lower horizons and reduces photosynthetic youth in the pet. Such waters are characterized by a peculiar vertical profile of photosynthesis with a pronounced, pressed to the surface, maximum layer. On the contrary, with deep penetration of solar rays, such as the transparent Lake Pleshcheyevo, as well as some areas of the Lower Volga, which receive, in addition and an increased dose of solar energy, primary production in a water column under 1 m3 reaches a high level with a relatively small biomass of algae (Pyrina, Rutkovskaya, 1976; Gerasimova, 1981; Pyrina, Sigareva, Dzyuban, 1989). In the lake In Pleshcheyevo, the increased yield of primary production per unit area is also due to the ecological features of mass forms of summer phytoplankton - dinoft algae of the genus Ceraiium, which can actively mix in search of optimal conditions for it (Heaney, Talling, 1980). Under intense solar radiation, they accumulate at a certain depth, in the zone of maximum photosynthesis, contributing to an increase in its values ​​per hundred liters of water iodine per 1 m; (Pyrina, Sigareva, Dzyuban, 14S9).

The patterns of distribution of photosynchronic intensity along the vertical profile are in general similar for all German studies and are determined mainly by the amount of pergestion at a given depth. Maximum foyueshpe! observed at depths where the irradiance is about 4.0 MD-k/m2 day PAR, and its attenuation is at 0.02 MJ/u3 ■ day. On clear days, such conditions are created at depths, respectively, 1-2 and 10 m to t.i Pleshcheyevo ("Pyrina, Sigareva. Dzyuban, 1989). 1.0-1 5 n 1-9 m i, Lake Ong-ch (Sorokin . Fedor ")", iУ69>, Ö-0.5 and 3-6 m and lake L. Kh.<(" vi* (üupiuu, ;сцсн, Ьакншчсин, 1976), 0-0,4 и 2-5 м в волжских водохранилищах (Пырина, Рутковская, 1976). Так, практически одна и та же энергия облученности (96 кал или 4,02 МДж на I м2 в сутки) наблюдалась на глубинах максимального фотосинтеза в Рыбинском вопохпл-ннлнще как весной, при интенсивной вегетации диатомовых, так и ж-(ом, когда в массе развивались сине зеленые (рис. 2). Однако в одном и том же водоеме эти, соответствующие характерным параметрам фото-синтезнрующей зоны, глубины могут значительно варьировать в шви-

Rice. 2. Vertical distribution of solar radiation (X = 380-800 nm) and photosynthesis of phytoplankton with a predominance of diatoms or snow-green algae. Rybinsk Reservoir, 1972

a - "blooming" of diatoms (May 16), b - "blooming" of synergy (July 7). 1 - photosynthesis in mg O/l.day, 2 - radiation e MJ/m "soup reduced to the MRE scale (Methodological letter... ¡982, cited from: Evnevich, 1984). The arrows indicate the energy of radiation at the depth of maximum photosynthesis .

simulation from the influx of solar radiation, which leads to a change in the integral values ​​of primary production under 1 mg (Pyrina, Mineeva, in press).

The efficiency of solar energy utilization during photosynthesis of phytoplankton in the studied reservoirs ranges from 0.01-i% of the integrated spectrum of radiation incident on the water, or 0.022% of the PAR energy. The highest values ​​(about 1%) were obtained in the area of ​​the Cheboksary Reservoir, in the Kuibyshev and Ivankovsky reservoirs, characterized by abundant phytoplankton (Pyrina, 1967 (a), 1978), as well as in Lake. Pleshcheev - due to the great depth of the photosynthetic zone (Pyrina, Sigareva, Dzyuban, 1989). These values ​​correspond to the largest known for highly productive fresh waters (Talling et al., 1973). Using the example of Lake Pleshcheyevo traced the mutual influence of indicators of the light regime and the amount of phytoplankton in the process of utilization of sunlight, which increases in proportion to the concentration of chlorophyll or 10 μg/l and decreases as they further increase and the manifestation of the “self-shading effect” (Pyrina, Sigareva, Dzyuban, 1989).

The relationship between the intensity of photosynthesis at the maximum along the vertical profile and the biomass of algae or the chlorophyll contained in them, which characterizes the assimilation activity of phytoplankton, varies within fairly close limits in all water bodies. In most cases, the ratio of photosynthesis to biomass (biomass activity coefficient) is 0.3-0.4 mg Qi/mg, and to chlorophyll (assimilation number) - 0.10-0.20 mg Og/µg per day. Their increased values ​​are typical for estuarine, shallow-water and other areas, in the phytoplankton of which green algae make up a significant proportion (Pyrina, 1959 (a), ¡967 (5), 1978; Pyrina. Trifonova. "." 79; Pyrina et al. 1981); Sigareva, 1984; Pyrina, Sngya-ro"i, Baloiov, 1989).

Targeted studies of primary production show that its maximum values ​​along the vertical profile are determined by the amount of foying plankton and the chlorophyll it contains, and the integral values ​​for the column are determined by the characteristics of the light regime, which determine the depth of spread of photosynthesis in the reservoir. As a result, in weakly colored transparent waters, taking absorbed little radiant energy, sent ■ ate the yield of photosynthesis per unit of chlorophyll and incoming solar radiation.The light factor determines the significant differences in the average annual values ​​of primary production associated with the duration of the period of intense solar energy intake and the depth of its penetration, depending on the height of the Sun above horizon.

VI. Oceica of light dependences of photosynthesis of phytoplaic-

In experiments to study the photosynthetic activity of phytoplankton depending on the energy of underwater solar radiation, carried out in a large water area of ​​the Middle and Lower Volga in the Rybinsk Reservoir and in Lake. Pleshcheev, a series of typical light curves of photosynthesis was obtained. After normalization" according to its maximum value for each sample, taken as 100%, the data from different experiments, established under similar irradiation conditions, turned out to be grouped quite closely, both with respect to the PAR energy and the general solar spectrum (Fig. 3). only some of their discrepancies depend on the composition of the dominant groups of algae: for phytoplankton with a predominance of green, the points were shifted towards high irradiation energy, and for phytoplankton from diatoms and, especially, blue-green algae - to the region of its lower values ​​(Pyrina, 1967; Pyrina, Rutkovskaya, 1976).

Such results are consistent with the patterns of vertical distribution of benthic algae in sea shelves, where green representatives more often grow in brightly lit conditions at shallow depths, while diatoms, brown and, especially, red ones penetrate deeper. A similar phenomenon has been noted in some deep freshwater bodies (Gessner, 1955; Kirk, 1983). Signs of light adaptation associated with the light-absorbing ability of pigments were also observed in marine phytoplankton raised from different depths (Koblenz-Mishke, 1980). However, in experiments with cultures (Curtis, Juday, 1937; Ichimura, Aruga, 1958; and others), including the isolation of plankton from the Rybinsk Reservoir (Pyrina, 1959), there were no similar patterns in the response of algae to SVST depending on the set of pigments was traced.

Taking into account this inconsistency, as well as the fact that the phytoplankton of the Volga, like other studied reservoirs, is represented mainly by diatoms and snow-greens, which turned out to be quite close in their relationship to light, a single light curve was constructed for the totality of the results of all experiments performed in the Volga reservoirs (Fig. 3). In this case, we used data on the energy of the general spectrum, which are most accessible to a wide range of researchers. Approximately, i.e. Without taking into account photoinhibition, which is relatively little expressed in the Volga reservoirs, the dependence of phytoplankton photosynthesis on solar radiation penetrating into the water was described by an equation of the form:

Az"=Iz/(0.35 + 0.009 l.J, (4)

5 10 50 yua)50 ¿50 /Gal!cis

Ivy radiation per day

Rice. 3. Relative rate of photosynthesis of phytoplankton in Volga reservoirs at different intensities of solar radiation input (general spectrum).

1,2 - phytoplankton with a predominance of blue-green algae or diatoms, respectively; 3 - mixed phytoplankton with a predominance of green ones. Photosynthesis in % of the maximum along the vertical profile; solar radiation energy in MD/s/m hut-on the MRE scale.

where 1g and Az"" radiation energy and the intensity of photosynthesis (in% of the maximum along the vertical profile) at depth r; Ar -(AJAMaKC) 100, where Ar and Amax are in absolute units. The resulting equation (4) is similar to the well-known Michaelis-Menten equation, which can be considered as the simplest of the common options for describing the effect of light on photosynthesis. In particular, it is a variation of the Bannister equation (Bannister, 1979):

A,=AMaKC!/(Ikm+Im) Ш (5)

(here A j and Amax are the intensity of photosynthesis at radiation energy / and maximum along the vertical profile, respectively; /^ ■ constant), which is quite universal and at t -I turns into the Michaelis-Menten equation, and at t = 2 into the equation Smith (Broth, 1994). The latter, as is known, forms the basis of the Talling model, adopted for calculating the integral primary production in a water column at 1 mg (Tailing, 1957; Vollenweider, et al., 1974). By varying the value of the parameter m, it is possible to describe light curves with a saturation region at a higher (for example, if m - 2) or low (»u = 3) light intensity.

Thus, the derived equation (4) corresponds to the light curves of photosynthesis with a fairly flat slope, leading to a shift of the maximum to the region of increased irradiation, and a weak manifestation of photoinhibition. It is possible that this type of dependence is to some extent related to the peculiarities of irradiance in the experiments, which changed in spectral terms as it decreased with depth. And yet, the lack of pronounced adaptation to light weakened by water can obviously be considered characteristic of the bulk of phytoplankton in the studied water bodies, where the mixing factor is significant and algae cells do not have to stay in deep water layers for a long time.

VII. The role of the characteristics of the light regime of different years in the interannual variability of phytoplankton productivity

Using the example of the Rybinsk Reservoir, for which the most complete series of data on chlorophyll content was obtained, changes in the level of phytoplankton productivity in a long-term plan were considered with a differentiated assessment of the role of anthropogenic and climatic factors, in particular, the solar radiation regime (Pyrina, 1991).

Analysis of these data showed an increase in the average chlorophyll content in the reservoir during the ice-free period, starting from 197! g. (Fig. 4). By the 80s, it reached a critical level (10 μg/l), beyond which the zoozoan is usually classified as eutrophic. This coincided with an increase in the amount of nutrients, especially total phosphorus, the concentrations of which in the Main Reservoir increased from 33-47 µg/l in 1965 and 1970. (on average for individual seasons) up to 40-60 µg/l in 1980 (Bylinkina, Trifonova, 1978; Razgulin, Gapeeva, Litvinov, 1982). They enter mainly through the Sheksninsky reach, which receives wastewater from the Cherepovets industrial complex, as indicated by a particularly sharp increase in chlorophyll concentrations in this section of the reservoir.

Against the background of a general increasing trend, high rises in chlorophyll concentrations stood out, corresponding to an outbreak of phytoplankton vegetation in years with anticyclonic weather (1972, 198!, 1984), which were due to the intense influx of solar radiation: 15-16 MJ/m* day. on average for the growing season (May - October) with the most frequent values ​​in the summer months ranging from 20-25 MD/m2 ■ day. Then the pigment content decreased slightly, but remained higher than in the years preceding the flare and remained around this level for several years, until the next period of increased solar radiation energy entering the Earth began (Fig. 4). In the nearby Ivankovskoe reservoir and lake. In Pleshcheyevo in these years (1972, 1973, 1984), increased values ​​of chlorophyll content (Table 2) and primary phytoplankton production (Table 3) were also observed. An increase in the level of primary production also occurred in other Volga reservoirs in years similar to hydrometeorological conditions, for example in 1975 (Table 3). In the lake Windermnr revealed a positive influence of solar radiation on the formation of the peak biomass of spring diatoms (K"ea! e1 a!., 1991), True, this (.kiyu affected the average annual level of phytoplankton biomass (chlorophyll content), which during the same period of years in was largely determined by other factors (TaShiv, 1993).

A significant increase in phytoplankton productivity in years with anticyclonic weather is explained by the influence of a complex set of conditions necessary for photosynthesis and the growth of algae biomass. Due to the intense intake of solar radiation, the depth of spread of photosynthesis increases and, accordingly, its integral value in the water column per unit area of ​​the reservoir increases. In the conditions of weakened wind conditions characteristic of such years, increased heating of the water column occurs and its stability increases. This promotes long-term residence of algae in the illuminated area with a high content of active (without derivatives) chlorophyll, their photosynthesis and growth. It is possible to stimulate both processes with biogenic elements, dust

17 16 15 N 13 12 I 10 9 V 7 6

1958 1971. 1975 1979 1983 1987 1991

1969 197E 1977 1901 1985 1989 1993 Ghana

Fig.4. Long-term changes in the intensity of incoming radiation and chlorophyll content in the Rybinsk Reservoir

solar

/ - energy of total solar radiation (total spectrum), MJ/m1 day, in average for May-October according to the Rybinsk Hydrometeorological Observatory; 2 average content of chlorophyll “a” (together with phgopigments) during the ice-free period, μg/l, in the upper 2-meter layer of water according to observations at standard stations of the Main Reservoir reach.

destroyed by bacterial destruction of organic matter, which is also enhanced by heat (Romanenko, 1985). Obviously, during the period of intense solar radiation, the ecosystem of the reservoir is enriched with energy utilized during photosynthesis, and the life processes of plant plankton are actually stimulated by nutrients; ensuring the growth of its biomass.

The results obtained reveal the main condition for the functioning of water systems - the obligatory influx of solar energy to maintain it. From this point of view, light plays a role no less important than biogenic elements in regulating the productivity of planktonic phytocenoses and the reservoir as a whole, including the process of its eutrophication. Thus, the solution to this global problem is associated with assessing the effect of the light fstor.

Conclusion

The main results of the research are as follows:

1. Depending on the transparency of the water, the depth of penetration of sunlight in the studied reservoirs varies widely, ranging from 2-5 m in the Volga reservoirs to 7-12 m in lakes Onega and Pleshcheyevo under intense insolation. Due to the attenuation of the extreme short-wave and long-wave rays “in the very layer of cola at a shallow depth of about 0.5-1.5 m, the penetrating radiation becomes identical in the spectrum of the PAR. Within the PAR extending deeper, the rays” of the blue region of the spectrum are most intensively attenuated, especially with increased color of the bottom, then red, while green penetrates to the maximum depth. In eanz" with selective attenuation of its radiation, its depth code will deviate it from the corresponding exponential law. The deviation can be compensated mathematically, which makes it possible to calculate the irradiation energy necessary for underwater photosynthesis from the intensity of solar radiation over a body of water, including the one registered by the nearest actmstrncheskon station.

2. The content of the main plant pigment - chlorophyll "a" varies from 1-2 μg/d b on average for the tegation period in the unproductive waters of Lake Onega and tundra lake. B. Kharbey up to 30 µg/l in the eutrophic Ivankovo ​​reservoir with maximum values ​​during the mass growing season of phytoplankton from 1.5-3 µg/l to 100 or more, respectively. The uniqueness of the seasonal dynamics of chlorophyll content in each group of water bodies, differing in the level of pigment content, can be traced: a sharp peak and relatively weakly expressed summer peaks in Lake. Pleshchee

in, equal in size - in the White Lake, spring, summer and autumn (or summer-autumn) - in the Rybinsk Reservoir, one summer - in the Ivankovskoye Reservoir, as well as in the tundra Kharbey lakes and, apparently, Lake Onega. In winter, with an almost complete absence of light under a thick layer of snow and ice cover, chlorophyll concentrations are close to 0. The patterns of spatial variability of chlorophyll content in all water bodies are quite similar and are associated mainly with the conditions of the hydrodynamic regime. No significant differences were found in the specific content of chlorophyll, as well as its ratio with other pigments for the homogeneous composition of the dominant algae of phytoplankton from different water bodies, as well as signs of light adaptation of its pigment system in optically different waters and in a seasonal aspect. At the same time, the limiting role of solar radiation in the process of formation and accumulation of chlorophyll derivatives is revealed, due to which a high content of its active fund is maintained during the most favorable periods for photosynthesis with anticyclonic weather. In years with the predominance of such periods, there is an increase in the overall level of chlorophyll content in the reservoir.

3. The level of primary production values ​​calculated per unit volume of water (at the maximum along the vertical profile) is determined by the amount of photosynthesizing plankton (chlorophyll content), and integral over depth - by the characteristics of the light regime, which determine the power of the photosynthesizing zone of the reservoir. As a result, in low-colored transparent waters, which absorb a relatively small amount of radiant energy, the yield of primary production of plankton per unit of chlorophyll and the solar energy entering the reservoir increases. Using the example of reservoirs of the Volga cascade, an increase in the average annual values ​​of primary production of phytoplankton towards the south due to increased intake of solar radiation. On the contrary, in tundra lakes, primary production is limited by the lack of light energy due to its limited entry into the reservoir at low solar altitudes above the horizon and the short duration of the ice-free period.

4. The study of light dependences of photosynthesis showed similarities in the response of communities of diatoms and blue-green algae typical of the studied reservoirs to the intensity of underwater irradiation. An analytical representation of this relationship has been found, which has made it possible to improve the calculation method for determining primary production.

5. Long-term data on chlorophyll content obtained in the Rybinsk Reservoir show that, against the background of interannual fluctuations, its increase occurs, indicating e-

trophy water reservoir. This coincides with an increase in nutrient load from the industrially developed part of the coast. However, sharp increases in pigment concentrations in years with a predominance

weather of anticyclonic type makes one believe about acceleration -----

this process with an increased supply of solar energy and thus consider light, along with biogenic elements^! as a factor in the eutrophication of the reservoir.

The conducted studies comprehensively show the important role of light in ensuring the photosynthetic activity of phytoplankton and the formation of their primary production. It is also important that the energy of solar radiation penetrating into a reservoir can be recorded using precise physical methods, as well as mathematical modeling, just like the process of underwater photosynthesis itself. In addition, in relation to planktonic phytocenoses, characterized by a relatively simple structure with close interaction with the habitat, the models are quite simple and adequate to the natural environment. All this expands the possibilities of instrumental and automated measurements in studies of the productivity of aquatic ecosystems.

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Main publications on the topic of the dissertation

Pyrina I.L. The intensity of photosynthesis in algae in connection with seasonal illumination // Tr. Inst. biol. Reservoir 1959. T. 1(4). pp. 102-109.

2. Pyrina I.L. Photosynthetic products in the Volga and its reservoirs // Bulletin. Ixt. biop. Reservoir 1959(a). N 3. P. 17-20.

3. Pyrnns I.L. Dependence of primary production on the composition of phytoplankton // Primary production of seas and inland waters. Minsk, 1961. P. 30.8-313.

4. Pyrina I.L. Preliminary results, application of the spectrophotometric method for determining pigments of freshwater phytoplankton // Biological aspects of studying reservoirs. M.-L., 1963. P. 51-59.

5. Pyrina I.L. Photosynthesis of freshwater phytoplankton under different light conditions in a reservoir // Abstracts of reports. 1 meeting on issues of the cycle of matter and energy in lake reservoirs. Listeenichnsya of Baikal, 1964. P. 81-62.

6. Pyrina I.L. Underwater photointegrator // Gidrobiol. magazine 1365, T.1, N 2. P. 61-07,

7. Pyrina I.L. Assessment of primary production of phytoplankton based on the results of measurements of chlorophyll content and the intensity of underwater radiation // Problems of hydrobiology (Abstracts of the 1st Congress of the All-Russian State Botanical Society). M„ 1965 (a). pp. 359-360.

8. Pyrina I.L., Feoktistova O.I., The role of blue-green algae in the production of organic matter in a reservoir // Ecology and physiology of blue-green algae. M.-L., 1965. P. 42-46.

9. Pyrina I.L. Primary production of phytoplankton in the Ivankovo, Rybinsk and Kuibyshev reservoirs depending on some factors // Production and circulation of organic matter in inland reservoirs - L., 1966. P. 249-270.

10. Pyrina I.L. Primary production of some reservoirs in connection with illumination, chlorophyll and phytoplankton biomass // Abstract of Ph.D. diss. Minsk, 1966 (a). 16 pages

11. Pyrina, I.L., Makeeva N.L. On the method for determining chlorophyll in algae cells collected on a membrane filter // Vegetation of the Volga reservoirs. M.-L., 1966. P. 198202.

12. Pyrina IL. Photosynthesis of freshwater phytoplankton under different light conditions in a reservoir // Matter and energy cycle in lake reservoirs. M., 1967. S. 202-208.

13. Pyrina I.L. Efficiency of solar energy utilization during photosynthesis of plankton in Volga reservoirs // Radiant factors in the life of aquatic organisms. L., 1967 (a). pp. 34-42.

14. Pyrina I.L. Dependence of phytoplankton photosynthesis on its biomass and chlorophyll content // Microflora, phytoplankton and higher vegetation of inland water bodies. L., 1967 (b). pp. 94-103.

15. Pyrina I.L. Primary production in reservoirs of the Upper and Middle Volga // Abstracts of reports. I conf. on the study of reservoirs of the Volga basin. Tolyatti, 1968. pp. 88-80.

16. Pyrina I.L. Intensity and spectral composition of sunlight in optically different waters // Second meeting. on issues of the cycle of matter and energy in lake reservoirs. Summary of reports, part I. Listvenichnoe on Baikal, 1969. pp. 83-84.

17. Pyrina I.L., Elizarova V.A. Chlorophyll content in phytoplankton of some fresh water bodies // Second meeting. on issues of the cycle of matter and energy in lake reservoirs. Summary of reports, part II. Larch on Baikal, 1969. pp. 9-10.

18. Pyrina I.L. Underwater illumination and chlorophyll as indicators of primary production of reservoirs // Biological processes in marine and continental reservoirs. (Theses of the report and congress of the VSBO). Chisinau, 1970. P. 314.

19. Pyrina I.L., Elizarova V.A. Spectrophotometric determination of chlorophylls in cultures of some algae II Biology and productivity of freshwater organisms. L., 1971. P. 5665.

20. Pyrina I.L., Naumova E.I. Photosynthetic activity of phytoplankton in waste waters of the Konakovo State District Power Plant // Tezi-

Sydokl. Symp. on the influence of thermal power plant waters on the hydrology and biology of water bodies. Borok, 1971. P. 52.

21. Guseva K.A., Priymachenko A.D., Pyrina I.L. Kozhova O.M., Gerasimova N.A., Kuksn M.S., Shalar V.M. Development of blue-green algae in reservoirs of hydroelectric power stations of the USSR // Abstracts of reports. All meeting on the integrated use of reservoirs. Kyiv, 1971. P. 41-42.

22. Pyrina P.L., Rutksvskaya V.A., Ilyinsky A.L. On the influence of phytoplankton on the penetration of solar radiation into the water of the Volga reservoirs II Organic matter and elements of the hydrological regime of the Volga reservoirs. L., 1972. S. 97-106.

23. Pyrina I.L., Getsen M.V., Elizarova V.A. Some indicators of the productivity of phytoplankton in the tundra Kharbey lakes // Cycle of matter and energy in lakes and reservoirs (Third Soyaeshchanke.. Summary of reports, collection 1). Listvenichnoa on Baikal, 1973. pp. 112-114.

24. Pyrina Sh1., Elizarova V.A., Nikolaev I.I. The content of photosynthetic pigments in the phytoplankton of Lake Onega and their significance for assessing the level of productivity of this reservoir II Productivity of Lake Onega. L., 1973. S. 108-122.

25. Pyrina I.L., Naumova E.I. The intensity of phytoplankton photosynthesis in the waste waters of the Konakovo State District Power Plant // Bulletin. Inst. biol. internal water InformM. Bulletin 1973. N 17. pp. 18-22.

26. Pyryaka Ya. L. Spectral measurements of underwater radiation in the photosynthetic wavelength range using a photointegrator with light filters II Radiation processes in the atmosphere and on the earth’s surface (Materials of the IX All-Union Meeting on Actinometry). L., 197-1. P. 423- 428.

27. Pyrina I.L. Primary production of phytoplankton in Volga reservoirs // Abstracts of reports. II conf. on the study of reservoirs of the Volga basin (summary of reports). Borok, 1974(a). pp. 20-24.

28. Pyrina I.L. Primary production of phytoplankton (section of the monograph) II Methods for studying the biogeocenoses of inland water bodies. M., 1975. S. 91-107.

29. Pyrina I.L. Penetration and spectral composition of sunlight in optically different waters and the cycle of matter and energy in lake reservoirs. Novosibirsk, 1^75 (a). pp. 349-353.

ZO^Pyrika I.L., Elizarova V.A. Chlorophyll content in phytoplankton of some freshwater bodies II Cycle of matter and energy in lake reservoirs. Novosibirsk, 1975. P. 85-89.

31. Pyrina I.L., Elizarova V.A. The intensity of photosynthesis and the content of chlorophyll in mass forms of phytoplankton in reservoirs of various types // Study and protection of water resources. M., 1975 (a). P. 60.

32. Pyrina I.L., Devyatkin V.G., Elizarova V.A. Experimental study of the effect of heating on the development and photosynthesis of phytoplankton // Anthropogenic factors in the life of reservoirs. L., 1975. S. 67-84. ,

33. Pyrina I.L., Bashkatova E.L., Sigareva L.E. Primary production of phytoplankton in the shallow zone of the Rybinsk reservoir in 1971-1972 // Hydrobiological regime of coastal shallow waters of the Upper Volga reservoirs. Yaroslavl, 1976. pp. 106-132.

34. Pyrina I.L., Getsen M.V., Vainshtein M.B. Primary production of phytoplankton in the lakes of the Kharbey system of the Bolshezemelskaya tundra (section of the monograph) // Productivity of lakes in the eastern part of the Bolshezemelskaya tundra. L., 1976. P. 63-76.

35. Elizarova V.A., Pyrina I.L., Getsen M.V. The content of phytoplankton pigments in the waters of the Kharbey lakes.//Ibid. P. 5563.

36. Pyrina I.L., Rutkovskaya V.A. Dependence of the intensity of photosynthesis of phytoplankton on the total solar radiation penetrating into the water // Biological production processes in the Volga basin. L., 1976. P. 48-66.

37. Guseva K.A., Priymachenko-Shevchenko A.D., Kozhova O.M., Pyrina I.L., Kuksn M.S., Shalar V.M., Chaikovskaya T.S., Gerasimova N.A. The intensity of “blooming” and the timing of mass vegetation of blue-green algae in the reservoirs of hydroelectric power stations of the USSR // Problems of regulating the “blooming” of water and the use of algae in the national economy. Kyiv, 1976. pp. 6-19.

38. Pyrina I.L., Elizarova V.A., Sigareva L.E. Signs of eutrophication of the Ivankovo ​​Reservoir in terms of phytoplankton productivity I. Anthropogenic eutrophication of natural waters. Chernogolovka, 1977. pp. 238-244.

39. Pyrina I.L. Primary production of phytoplankton (section of the monograph) // Ivankovo ​​Reservoir and its life. L., 1978. S. 102-124.

40. Pyrina I.L. Primary production of phytoplankton (section of the monograph) // Volga and its life. L., 1978 (a). P.148-152.

41. Pyrina I.L., Bashkatova E.L., Mineeva N.M., Sigareva L.E. Some indicators of phytoplankton productivity in the Sheksninsky reservoir and adjacent lakes II Biological resources of water bodies of the Vologda region, their protection and rational use

calling (abstracts for a scientific-practical conference). Vologda, 1978. pp. 20-21.

42. Pyrina I.L., Sigareva L.E. The content of phytoplankton pigments in the Ivankoz reservoir in 1973-1974 // Biology of lower organisms. Rybinsk, 1978, pp. 3-17,

43. Pyrina I.L. Primary production of phytoplankton In the Volga (monograph section) //The river Volga and Its life. Hague, 1979. P. 180-194.

44. Pyrina I.L. Determination of primary production of phytoplankton based on maximum photosynthesis, total solar radiation and water transparency // Gidrobiol. magazine 1979. T. 15, N 6. P. 109-113.

45. Pyrina I.L., Trifonova I.S. Research on the productivity of phytoplankton in Lake Ladoga//Gidrobiol. magazine 1979. T. 15, N 4. P. 26-31.

46. ​​Pyrina I.L., Elizarova V.A. Comparative characteristics of milkings of different trophic levels in terms of chlorophyll content // Matter cycle and biological self-purification of water bodies. Kyiv, 1980. P. 100-109.

47. Tilzer M.M., Pyrina I.L., Westlake D.F. Phytoplankton photosynthesis (section of the monograph) // The functioning of freshwater ecosystems. Cambridge, 1980. pp. 163-170,174-176.

48. Pyrina I.L., Mineeva N.M., Korneva L.G., Letanskaya G.I. Phytoplankton and its products (section of the monograph) // Anthropogenic influence on large lakes of the north-west of the USSR. Part II. Hydrobiology

and hydrochemistry of White Lake. P., 1981. P. 15-64.

49. Pyrina I.L. On the lower light limit of phytoplankton vegetation under ice // Problems of ecology of the Baikal region.!!. Monitoring the bacterial population of water bodies. Irkutsk, 1982. pp. 85-86.

50. Pyrina I.L., Smetanin MM: On the assessment of average values ​​for a reservoir of quantitative characteristics of phytoplankton /■ "Estimation of errors in hydrobiological and ichthyological studies. Rybinsk, 1982, pp. 144-156.

51..Pyrina ^ I.L. . studies of photo-synthetically active radiation penetrating under ice //Radiation Climatology and

applied aspects of actinometry (Materials of the XI! meeting on actinometry). Irkutsk, 1984. pp. 252-254.

52, Pyrina I.L. The relationship between visible and total solar radiation over the reservoirs of the Upper Eolga basin//Cycle of matter and energy in reservoirs. Irkutsk, 1985. pp. 38-40.

53. Pyrina I.L. Conditions of the light regime and the development of phytoplankton during the subglacial period in large lake reservoirs of the north-west // Problems of research of large lakes of the USSR. L„ 1985 (a). pp. 111-114.

54. Pyrina I.L., Sigareva L.E. The content of phytoplankton pigments in the Rybinsk Reservoir in years of different hydrometeorological conditions (1972-1976) // Biology and ecology of aquatic organisms. L., 1986. P. 65-89.

55. Mineeva N.M., Pyrina I.L. Studies of phytoplankton pigments in the Rybinsk Reservoir and Ibid. pp. 90-104.

56. Pyrina I.L., Mineeva N.M., Sigareva L.E. Long-term studies of phytoplankton pigments in the Rybinsk Reservoir // V Congress of the VSBO, Part I. Abstracts of reports. Kuibyshev, 1986. pp. 208-209.

57. Priymachenko A.D., Pyrina I.L., Votyakova N.E. Pigment composition and photosynthetic activity of plankton and benthos of the river. Yenisei // Ibid., part II. pp. 254-285.

58. Pyrina I.L., Mineeva N.M., Sigareva L.E., Balonov I.M., Mazin A.M. On the productivity of phytoplankton in Lake Pleshcheyevo // Protection and rational use of internal waters of the Center and North of the Russian Plain. Yaroslavl. 1986. pp. 36-40.

59. Pyrina I.L. On the weakening of solar radiation in natural waters II First Vereshchagin Baikal International Conference. Abstracts of reports. Irkutsk, 1989. pp. 35-36.

60. Pyrina I.L. On the attenuation of solar radiation in natural waters. "//. The first Vereschagin Baikal internatienol conference. Abstracts. Irkutsk, 1989, P. 35-36.

61. Pyrina I.L. Hydro-optical characteristics and light regime (section of the monograph) II Ecosystem of Lake Pleshcheyevo. L., 1989 (a). S. 3540."

62. Pyrina I.L., Sigareva L.E., Balonov I.M. Phytoplankton and its production capacity // Ibid. pp. 71-114.

63. Pyrina I.L., Sigareva L.E., Dzyuban A.N. Primary production of phytoplankton // Ibid., pp. 114-122.

64. Bikbulatov. E.S., Dzyuban A.N., Pyrina I.L. Balance of organic matter//Ibid. pp. 216-218.

65. Dzyuban A.N., Pyrina I.L. Trophic state and water quality // Ibid. pp. 218-221.

66. Pyrina I.L., Mineeva N.M. Content of phytoplankton pigments in the water column of the Rybinsk Reservoir // Flora and productivity of pelagic and littoral phytocenoses of water bodies of the Volga basin. L., 1990. S. 176-188.

67. Pyrina I.L. Long-term dynamics of chlorophyll and productivity of plant plankton in the Rybinsk Reservoir // Ecological aspects of the regulation of plant growth and productivity. Yaroslavl. 1991. pp. 253-259.

68. Pyrina I.L. Chlorophyll content and productivity of phytoplankton in the lake. Pleshcheyevo // Factors and processes of eutrophication of Lake Pleshcheyevo. Yaroslavl, 1992. pp. 18-21).

69. Pyrina I.L., Lyashchenko O.A. Composition and productivity of phytoplankton in lake. Pleshcheyevo at the present stage. // Abstracts of the report. All-Russian scientific Conf., dedicated to the 300th anniversary of the domestic trade union. Pereslzl-Zalegky, 1992. pp. 112-114.

70. Pyrina I.P., Lyashenko O.A. Composition and productivity of phyto-planets of the lake. Pleshcheev at the present stage. // Tr. All-Russian Izumi, conf. dedicated to the 300th anniversary of the Russian fleet. yyl.Sh. Shreslavl-Zalskiy. 1392. pp. 48-54.

71. Pyrina IL. Oxygen method for determining nepciv-mcfi phytoplankton production // Methodological issues in studying the primary production of plankton in internal water bodies. Syacht-Petersburg, 1053. pp. 10-13.

72 Pmrina I.L. Features of conditions for photosynthesis and isolated samples;; phytoplankton. // Ibid. pp. 21-23.

73. Pyrina PL. Determination of underwater photosithetic ac-

1IPM11L MYAP1LYAIMM N lOII WAf

74. Mbtjjwha i"i.."!., vf.-.eiaiiiiHM.fvi. Calculation of integral and average values ​​of primary production and assessment of their accuracy. // Ibid. pp. 30-40.

75. Pyrina IL. Retrospective analysis of data on the primary production of Volga phytoplankton // Ecological problems of large river basins. Tolyatti, 1993 (a): pp. 129-130.

78. Pyrina I.L., Priymachenko-A.D. The content of phyto-planeton pigments in the river. Yenisei (section of the monograph) // Productive and hydrobiological studies of the Yenisei. Novosibirsk, 1993. P.

7-" Perina I..P., mineeza N.M., Cnrfepfetiä l.E,. .imnao;: ; A D Filimonov V.S., Mitropolskal M.U. Spatially? .."spso-children's phytoplankton (p^zdol." :> Ecologist rfi-wi,~ FOGT.5rY prog.trlysteennogo RYSPRODSG.SIIK L.trenvshcheima (ID-roOkontov St. Petersburg, 19EZ. P. 55-8-1. 70. Pyrina I.L., Smetaniya M.M. ., Smetznnnna TL. Sgatshshmvsk" approach to assessing the concentrations of pigments and biomass of the phytoplankton gene and Assessment of phytoplankton productivity. Noeosibirsk, 1993. P. 30-4 4.

79. Pyrina I.L. Indicators of primary production of phytoplankton in

kesgzde reservoirs river. Volga // Microflora and biological penetration in inland waters". St. Petersburg (about print). 60. Pyrina I.L., Dobrynin E.G., Mineeva N.M., Sigareva L.E. On the influence of photosynthesis and destruction of organic matter on the oxygen regime of a stratified lake. Ibid. 81. Pmpiche I.L., M^meeva N.M. Penetration of sunlight and parameters of the photosynthesis zone in the Rybinsk Reservoir // Structure and productivity of phytoplankton of the Rybinsk Reservoir. Tolyatti (in press )-

FISHERIES UDC 574.583(28):581 Yu. A. Gorbunova, A. V. Gorbunova * Astrakhan State Technical University * Astrakhan State Biosphere Reserve RELATIONSHIP OF PHYTOPLANKTON PRODUCTIVITY IN THE VOLGA DELTA WITH PHYSICAL ENVIRONMENTAL FACTORS To the main physical environmental factors that determine seasonal dynamics and productivity phytoplankton, relate primarily to the intensity of solar radiation and water temperature. It is well known that in the process of photosynthesis, the energy of solar radiation absorbed by the photosynthetic pigments of phytoplankton, the most important role among which is played by chlorophyll a, is transformed into the energy of chemical bonds of organic compounds, and thereby the process of primary production of plankton occurs. Along with solar radiation, the most important factor determining the development of phytoplankton and its productivity is water temperature. Different types of planktonic algae differ in their temperature optimum, and the higher the temperature optimum, the more intense photosynthesis and the rate of division the algae are capable of. Materials and methods of research The work is based on field observation data carried out in the lower zone of the Volga delta and avandelta on the basis of the Astrakhan Biosphere Reserve from 1994 to 2004. The intensity of plankton photosynthesis was determined by an oxygen modification of the flask method. The concentration of chlorophyll a was determined using a standard spectrophotometric method; the calculation was made using the Jeffrey and Humphrey formula. The arrival of total solar radiation is presented according to ACGMS data. To characterize the temperature regime, data from the phenohydrometeo station of the Astrakhan Biosphere Reserve were used. Statistical processing of the material was carried out using generally accepted methods and using specialized software packages Mathcad and STATISTICA 6.0. Relationship between phytoplankton productivity and temperature regime The temperature regime of watercourses and reservoirs in the Volga delta largely depends on the temperature of the water entering the delta from the upstream sections of the river and changes in air temperature. The increase and decrease in water temperature in the watercourses of the lower delta zone occurs gradually, the daily fluctuation, as a rule, does not exceed one degree. The water temperature of the bottom layer does not differ from the temperature of the surface layer - this is facilitated by good water flow and turbulent flow movement. 83 ISSN 1812-9498. AGTU NEWSLETTER. 2006. No. 3 (32) The annual course of water temperature largely determines seasonal differences in phytoplankton productivity. The temperature factor becomes especially important during cold periods of the year. In spring, with an increase in water temperature, the intensity of plankton photosynthesis, insignificant in March, increases 2–5 times in April. In the autumn period, significant differences in the intensity of plankton photosynthesis are observed in different years, which is largely explained by weather conditions, which can vary greatly from year to year. As a rule, as long as the region is under the influence of the spur of the Asian anticyclone, clear, warm weather helps maintain photosynthetic processes at a high level. With the establishment of cyclonic weather, accompanied by sharp cooling and frequent rainy or cloudy days, the intensity of photosynthesis sharply decreases. The temperature regime of the shallow water delta front differs from the temperature regime of the channels of the above-water delta - the water layer warms up and cools faster. Daily fluctuations in water temperature in the delta front can be significant, reaching 10 °C. The greatest unevenness in the spatial distribution of water temperature is observed in the spring before the onset of floods, when, with an increase in solar radiation and an increase in air temperature in shallow water conditions, a significant warming of the delta-front water area occurs in comparison with watercourses. In some areas of the delta front, the difference in water temperature compared to watercourses can be 10–15 C. During this period, temperature is the leading factor in the spatial heterogeneity of phytoplankton; the intensity of phytoplankton vegetation in the delta front, especially in certain areas, significantly exceeds that in the channels. The most productive areas are the well-warmed coastal areas of the islands. For watercourses in the lower zone of the Volga delta, when conducting a correlation analysis between the sum of water temperatures for a month and the average rate of photosynthesis of phytoplankton for a month and the sum of water temperatures for a month and the average monthly concentration of chlorophyll a in plankton, in both cases a different nature of the relationship was obtained for summer-autumn phytoplankton and spring and late autumn phytoplankton (Fig. 1). The correlation between the sum of water temperatures per month and the average rate of phytoplankton photosynthesis per month turned out to be positive and quite high. In the case of spring and late autumn phytoplankton, the correlation coefficient was +0.90 (rmin = 0.51; р< 0,05); в случае летнеосеннего фитопланктона соответственно +0,62, (rmin = 0,42; р < 0,05). Корреляция между суммой температур воды за месяц и среднемесячной концентрацией хлорофилла а в планктоне также оказалась положительной и довольно высокой. В случае весеннего и позднеосеннего фитопланктона коэффициент корреляции составил +0,92 (rmin = 0,42; р < 0,05); в случае летне-осеннего фитопланктона соответственно +0,66 (rmin = 0,43; р < 0,05). 84 РЫБНОЕ ХОЗЯЙСТВО гО2 м-3 сут-1 мгм -3 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 12 10 8 6 4 2 0 0 5 1 10 215 а 20 25 30 0 10 20 оС С 30 СоС б Рис. 1. Зависимость средней за месяц интенсивности фотосинтеза (а) и среднего за месяц содержания хлорофилла а в планктоне (б) от среднемесячной температуры воды: 1 – весенний и позднеосенний фитопланктон; 2 – летне-осенний фитопланктон. Ось абсцисс – температура воды; ось ординат: а – интенсивность фотосинтеза планктона; б – содержание хлорофилла а в планктоне Для весеннего и позднеосеннего фитопланктона различие коэффициентов корреляции между температурой воды и скоростью фотосинтеза фитопланктона и между температурой воды и уровнем содержания хлорофилла а незначимо (uz`-z`` = 0,14; u05 = 1,96). В то же время для летнеосеннего фитопланктона различие между обоими выборочными коэффициентами корреляции является значимым (uz`-z`` = 2,27; u05 = 1,96). Связь продуктивности фитопланктона с солнечной радиацией Количество солнечной радиации, доходящее до поверхности воды, определяется географической широтой и изменяется с погодными условиями. В среднем за год общий приход суммарной солнечной радиации в регионе составляет 5 146 МДж·м-2. Интенсивность солнечной радиации значительно меняется по сезонам года, что связано с годовым ходом высоты Солнца. Поверхность региона получает в летние месяцы в 4,5 раза больше солнечной радиации по сравнению с зимним периодом. Погодные условия дельты Волги с середины апреля и до середины октября в основном обусловлены воздействием отрогов азорского антициклона, перемещающихся с запада на восток. При таких синоптических процессах устанавливается малооблачная погода . Солнечные лучи, падая на водную поверхность, частично отражаются от нее, частично же, преломляясь, проникают вглубь. Световой поток, проникая в воду, подвергается ослаблению за счет избирательного поглощения и рассеяния тем сильнее, чем больше содержание взвешенных частиц. Мутность воды в низовьях дельты Волги зависит как от количества взвешенных наносов, приносимых Волгой, так и от наносов, поступающих в водоемы вследствие эрозионных процессов, происходящих в руслах водотоков дельты . Максимальное содержание в воде взвесей в дельте наблюдается в первой половине мая – значительно раньше прохожде85 ISSN 1812-9498. ВЕСТНИК АГТУ. 2006. № 3 (32) ния пика половодья. В авандельте содержание в воде взвесей значительно меньше, чем в водотоках дельты – на протяжении большей части года в условиях мелководья на подавляющем большинстве станций относительная прозрачность наблюдается до дна. Различие условий проникновения солнечной радиации в воду является одним из ведущих факторов, обусловливающих большую эффективность утилизации фитопланктоном энергии солнечной радиации, падающей на водное зеркало в авандельте, где значения могут достигать 0,16-0,28 %, в водотоках эти показатели достигают лишь 0,07-0,08 % . Сезонные различия интенсивности солнечной радиации в большой мере определяют изменения продуктивности фитопланктона в течение года. Это влияние проявляется в непосредственном участии энергии солнечной радиации в фотосинтетическом процессе, составляя его энергетическую основу. В то же время солнечная радиация оказывает большое влияние на температуру воды. При этом ход температуры воды в протоках запаздывает по сравнению с интенсивностью суммарной солнечной радиации примерно на месяц (рис. 2, а). Вычисление коэффициента корреляции между месячными суммами суммарной солнечной радиации за предыдущий месяц и месячными суммами температуры воды за последующий месяц показало тесную положительную связь (рис. 2, б). Коэффициент корреляции составил +0,96 (rmin = 0,42; р < 0,05). МДжм -2 900 700 500 300 100 С Январь Февраль Март Апрель Май Июнь Июль Август Сентябрь Октябрь Ноябрь Декабрь 800 600 400 200 0 1 2 3 4 МДжм-2 900 800 700 600 500 400 300 200 100 0 0 200 400 600 800 1000 С а б Рис. 2. Годовой ход величины суммарной солнечной радиации и суммы температур воды (а) и связь этих показателей (б) за 1999 и 2000 гг.: а – первая ось ординат – годовой ход величины суммарной солнечной радиации; вторая ось ординат – сумма температур воды: 1 – месячные суммы суммарной солнечной радиации за 1999 г.; 2 – месячные суммы суммарной солнечной радиации за 2000 г.; 3 – месячные суммы температуры воды за 1999 г.; 4 – месячные суммы температуры воды за 2000 г.; б – ось абсцисс – сумма температуры воды; ось ординат – суммарная солнечная радиация 86 РЫБНОЕ ХОЗЯЙСТВО Корреляционный анализ показал, что наблюдалась тесная зависимость между месячными показателями энергии солнечной радиации и средней за месяц скоростью фотосинтеза фитопланктона в водотоках (рис. 3, а). Коэффициент корреляции составил +0,81 (rmin = 0,51; р < 0,05). Была также установлена связь между месячными показателями энергии солнечной радиации и среднемесячной концентрацией хлорофилла а в планктоне водотоков (рис. 3, б). Коэффициент корреляции составил +0,83 (rmin = 0,36; р < 0,05). гО2 м-3 сут-1 1,4 мгм-3 20 1,2 15 1,0 0,8 10 0,6 0,4 5 0,2 0,0 0 0 200 400 600 а 800 1000 0 200 400 600 800 1000 б Рис. 3. Зависимость средней за месяц скорости фотосинтеза планктона (а) и средней за месяц концентрации хлорофилла а в планктоне (б) от месячного прихода суммарной солнечной радиации. Ось абсцисс – приход суммарной солнечной радиации за месяц; ось ординат: а – скорость фотосинтеза планктона; б – концентрация хлорофилла а в планктоне Заключение Продуктивность фитопланктона и ее сезонная динамика в значительной степени определяются годовым ходом температуры воды и интенсивности солнечной радиации. Корреляционный анализ выявил значимую связь скорости фотосинтеза фитопланктона и содержания хлорофилла а с этими факторами среды. При этом получен разный характер связи продукционных характеристик летне-осеннего фитопланктона и фитопланктона весеннего и позднеосеннего с температурой воды. Для весеннего и позднеосеннего фитопланктона различие коэффициентов корреляции между скоростью фотосинтеза и температурой воды и между содержанием хлорофилла а и температурой воды незначимо, в то время как для летнеосеннего фитопланктона различие между обоими выборочными коэффициентами корреляции значимо. Температура оказывает непосредственное влияние на интенсивность физиологических процессов, в том числе на скорость фотосинтеза, и лишь косвенно определяет уровень содержания хлорофилла а. Влияние солнечной радиации на интенсивность процессов фотосинтеза имеет двоякий характер: с одной стороны, она непосредственно участвует в фотосинтезе, являясь энергетической основой этого процесса, с другой – опосредованно воздействует на уровень метаболизма фитопланктона, влияя на температуру воды. 87 ISSN 1812-9498. ВЕСТНИК АГТУ. 2006. № 3 (32) Авторы выражают искреннюю благодарность Л. М. Вознесенской за помощь и данные по солнечной радиации. СПИСОК ЛИТЕРАТУРЫ 1. Роль гидрометеорологических условий в многолетней динамике продуктивности фитопланктона во внутренних водоемах / А. С. Литвинов, И. Л. Пырина, В. Ф. Рощупко, Е. Н. Соколова // Природно-ресурсные, экологические и социально-экономические проблемы окружающей среды в крупных речных бассейнах. – М.: Медиа-Пресс, 2005. – С. 70–81. 2. Михеева Т. М. Сукцессия видов в фитопланктоне: определяющие факторы. – Минск: Изд-во БГУ, 1983. – 72 с. 3. Девяткин В. Г., Метелева Н. Ю., Митропольская И. В. Гидрофизические факторы продуктивности литорального фитопланктона: Влияние гидрофизических факторов на динамику фотосинтеза фитопланктона // Биология внутренних вод. – 2000. – № 1. – С. 45–52. 4. Сиренко Л. А. Активность Солнца и «цветение» воды // Гидробиологический журнал. – 2002. – Т. 38, № 4. – С. 3–10. 5. Alternation of factors limiting phytoplankton production in the Cape Fear River Estuary / M. A. Mallin, L. W. Cahoon, M. R. McIver et al. // Estuaries. – 1999. – Vol. 22, N 4. – P. 825–836. 6. Eppley R. W. Temperature and phytoplankton growth in the sea // Fish. Bull. – 1972. – Vol. 70. – P. 1063–1085. 7. Винберг Г. Г. Первичная продукция водоемов. – Минск, 1960. – 329 с. 8. SCOR-UNESCO Working Group N 17. Determination of photosynthetic pigments in sea water // Monographs on oceanographic methodology. – P.: UNESCO, 1966. – P. 9–18. 9. Lorenzen C. J., Jeffrey S. W. Determination of chlorophyll in sea water. – P.: UNESCO, 1980. – 20 p. (UNESCO Techn. Pap. in Mar. Sci.; 35). 10. Jeffrey S. W., Humphrey G. F. New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants algae and na tural phytoplankton // Biochem. Physiol. Pflanzen. – 1975. – Bd. 167, N 2. – S. 191–194. 11. Урбах В. Ю. Биометрические методы. – М.: Наука, 1964. – 415 с. 12. Лакин Г. Ф. Биометрия. – М.: Высш. шк., 1980. – 293 с. 13. Гланц С. Медико-биологическая статистика. – М.: Практика, 1999. – 459 с. 14. Москаленко А. В. Характеристика гидрологического режима водоемов низовьев дельты Волги // Тр. Астрахан. заповедника. – Астрахань, 1965. – Вып. 10. – С. 37–79. 15. Вознесенская Л. М., Бесчетнова Э. И. Климатические особенности и опасные явления погоды Астраханской области в ХХ веке. – Астрахань, 2002. – 111 с. 16. Москаленко А. В., Русаков Г. В. Влияние зарегулированности водного стока реки Волги на сток взвешенных наносов в рукавах ее дельты. – Деп. в ВИНИТИ № 2997 – 79 от 08.05.79. – Вестн. МГУ. Сер. географ. – 1979. – № 3. – 14 с. 17. Горбунова Ю. А. Продуктивность фитопланктона дельты Волги: Автореф. дис. … канд. биол. наук. – Борок, 2005. – 23 с. Статья поступила в редакцию 24.03.06, в окончательном варианте – 21.04.06 88 РЫБНОЕ ХОЗЯЙСТВО THE DEPENDENCE OF PHYTOPLANKTON PRODUCTIVITY OF THE DELTA OF THE RIVER VOLGA ON PHYSICAL ENVIRONMENTAL FACTORS Yu. A. Gorbunova, A. V. Gorbunova The dependence of phytoplankton productivity of channels of the delta and the avandelta of the river Volga on the water temperature and solar radiation intensity is considered in the paper. The correlation analysis has revealed a significant relation of photosynthesis rate and chlorophyll contents with these environmental factors. The authors of the article have obtained different characters of relations of production characteristics with the water temperature for summer-autumn phytoplankton and spring and late autumn phytoplankton. 89

Introduction

Chapter 1. Material and research methods 7

Chapter 2. Characteristics of the study area 13

Chapter 3. Phytoplankton, its seasonal dynamics and spatial distribution - 21

3.1 Seasonal dynamics of the qualitative composition of phytoplankton in watercourses22

3.2. Characteristics of the spatial distribution of phytoplankton - 27

3.3. Cluster analysis of the spatial distribution of phytoplankton - 49

3.4. Relationship between the spatial distribution of phytoplankton and hydrological factors and the phenomenon of phytoplankton sedimentation in the delta front 52

Chapter 4. Seasonal dynamics and spatial distribution of plankton photosynthetic pigments - 55

4.1 Seasonal dynamics of chlorophyll a and other photosynthetic pigments of plankton in watercourses - 57

4.2. Spatiotemporal distribution of chlorophyll a and other photosynthetic pigments of plankton in the delta front - 79

4.3. The relationship between the content of chlorophyll a and phytoplankton biomass - 88

Chapter 5. Primary plankton production 92

5.1. Seasonal dynamics and spatial distribution 92

5.2. Efficiency of solar radiation energy utilization during plankton photosynthesis 98

5.3. Primary production of plankton in the Volga delta in comparison with the mouths of other rivers - 102

Chapter 6. Retrospective analysis of phytoplankton productivity indicators and their relationship with various factors - 109

6.1. Primary plankton production and trophic status of the lower zone of the Volga delta in different periods of regulated flow 109

6.2. Relationship between phytoplankton productivity indicators and environmental factors 115

6.4. The influence of anthropogenic input of nutrients and parameters of the Volga water flow on the productivity of delta phytoplankton 132

Conclusions 138

Literature 140

Introduction to the work

Relevance of the problem . One of the main tasks of hydrobiology is to develop a theory of the biological productivity of aquatic ecosystems (Alimov, 2001). According to the generally accepted position of G. G. Vinberg (1960), the primary production of aquatic ecosystems, along with the allochthonous organic matter entering them, constitutes the material and energy basis of all subsequent stages of the production process. Quantitative studies of the intensity of production processes, primarily primary production, are the basis of the modern system of typology of reservoirs (Bouillon, 1983). Determination of phytoplankton productivity indicators is an integral part of water quality monitoring (Abakumov, Sushchenya, 1992; Oksiyuk et al., 1993).

The Volga Delta is a unique natural object that performs the most important biosphere function of maintaining the homeostasis of the region's wetlands and is of great economic importance. Over the past almost half a century of regulated Volga flow, significant changes in environmental conditions have occurred in its delta, mainly due to fluctuations in water flow, its anthropogenic intra-annual redistribution, changing levels of pollutants and nutrients, and other anthropogenic and natural factors. In this regard, the formulation of the concept of environmental sustainability and vulnerability of aquatic ecosystems in the region and the assessment of their biological productivity are of particular relevance. Therefore, studying the productivity of phytoplankton in the Volga delta is especially relevant under the current conditions.

Purpose and objectives of the study . The purpose of the work is to study the productivity of phytoplankton in the Volga delta.

In accordance with the goal, the following tasks were formulated:

Investigate the seasonal dynamics and spatial distribution of phytoplankton;

Study the seasonal dynamics and spatial distribution of plant pigments in plankton;

Investigate the seasonal dynamics and spatial distribution of photosynthesis intensity;

4. Analyze the relationship between chlorophyll concentration A With
phytoplankton biomass and photosynthesis intensity;

Identify the main environmental factors that determine phytoplankton productivity;

Assess the current state of primary plankton production in a number of years of regulated water flow.

Scientific novelty . A comprehensive assessment of the current state of phytoplankton productivity and trophic status of the lower reaches of the Volga delta was carried out. For the first time, the content and dynamics of plant pigments in plankton were studied in detail, the values ​​of the assimilation number were obtained as a measure of the photosynthetic activity of chlorophyll A in the studied water bodies. The features of the primary production of plankton in the lower zone of the delta and delta front of the Volga are revealed, and the processes of removal and sedimentation of phytoplankton in the delta front are considered.

Practical significance . The Volga Delta and its pre-estuary coastal zone play an important role in maintaining the ecological balance in the vast adjacent land area and water area of ​​the Caspian Sea. The results obtained can serve as the basis for the development of methods for the rational use and protection of biological water resources

objects in the region, planning measures to increase their productivity, to build a model of biological production under various options for regulating the Volga flow and the changing anthropogenic component of the influx of nutrients. Research materials are included as an integral part of the monitoring system carried out by the Astrakhan Biosphere Reserve, and are also used in the educational process of the Institute of Biology and Environmental Management of ASTU.

Approbation of work . The dissertation materials were presented at the Scientific Conference “State, study and conservation of natural complexes of the Astrakhan Biosphere Reserve in conditions of rising Caspian Sea levels and increasing anthropogenic pressure” (Astrakhan, 1999); International conference “New technologies in the protection of biodiversity in aquatic ecosystems” (Moscow, 2002); at the Second International Conference “Biotechnology - Environmental Protection” (Moscow, 2004); International Conference “Problems and Prospects for the Rehabilitation of Technogenic Ecosystems” (Astrakhan, 2004); at the International Conference “Primary Production of Aquatic Ecosystems” (Bo-rock, 2004); at scientific and practical conferences of the teaching staff of the Astrakhan State Technical University in 1999-2004.

Publications . 8 works have been published on the topic of the dissertation.

Structure and scope of the dissertation . The dissertation is presented on 163 pages, includes 12 tables, 26 figures. Consists of an introduction, 6 chapters and conclusions. The bibliography includes 230 titles, including 70 in foreign languages.

Characteristics of the spatial distribution of phytoplankton

In the watercourses of the lower delta zone and in the delta front, different ecological conditions develop, which is reflected in the species composition of phytoplankton, its distribution and abundance. Differences in the development of algae can also be traced according to the seasons of the year. During the growing season, several periods can be distinguished with a characteristic pattern of distribution and quantitative development of phytoplankton.

The lowest quantitative development of phytoplankton in all types of water bodies is observed in the cold season. At the same time, the dominant position in the channels is occupied by representatives of the class of pennate diatoms, primarily the genus Cymbella, Gomphonema, NavicuJa, Nitzschia, Synedra. The total biomass of phytoplankton usually does not exceed 0.01-0.30 gm3.

In the spring, before the onset of the flood, with an increase in solar radiation and warming of the water, the beginning of the mass development of phytoplankton is observed. The water is heated unevenly and the spatial distribution of phytoplankton is characterized by a large patchiness. The greatest warming is observed in the coastal area of ​​the Avandelta islands. In these areas, the biomass of phytoplankton exceeds that in other areas and is about 0.8-0.9 gm"3, and at some stations more than 1 gm"3 (Table 3.2.1.). The distribution of phytoplankton during this period is shown in Fig. 3.2.1.a. using the example of April 2000. Pennate diatoms make a large contribution to the phytoplankton biomass of the coastal areas of the delta-front islands, accounting for 50-75% of the total biomass. First of all, these are representatives of the genera Surirella and Nitzschia.

Algae of the divisions Chlorophyta (Chiorella, Pediastrum, Closterium) and Cyanophyta (Lyngbya, Oscillatoria) also develop in significant quantities, occupying a dominant position at some stations. In the open areas of the delta front, the quantitative development of phytoplankton during this period is less, the biomass is about 0.3-0.4 gm. In the channels during this period, the phytoplankton biomass, in comparison with the open areas of the delta front, is observed in different years to be lower or comparable to it, amounting to 0.04-0.4 gm"3. The dominant species are winter phytoplankton, primarily representatives of the genera Niizschia and Cymbella, as well as Aulacosira, Stephanodiscux, Amphora, Cocconeis, Gornphonema, Navicula, Rhoicosphenia.

In the second half of May, at the peak of the flood, there is a peak in the development of phytoplankton in the channels, which can be called spring-summer. At the same time, the phytoplankton biomass has a fairly uniform spatial distribution and a similar species composition is observed. This is explained by the fact that during flood conditions, high water levels and high current speeds determine, on the one hand, the same type of conditions, especially in channels and in open areas of the delta front, and on the other hand, provide significant transit drift of planktonic algae. The distribution of phytoplankton at the peak of the flood is shown in Fig. 3.2L.6. using the example of May 2000. During this period, centric diatoms acquire a leading role in the channels among the Bacillariophyta department, primarily due to the mass vegetation of Stephanodiscvs hantzschii. Algae of the Chlorophyta department, especially Chiorella vulgaris Beijer, are developing significantly. These species (S. hantzschli and Ch. vulgaris) are found in significant quantities at most stations in open and coastal areas of the delta front. The biomass of phytoplankton in the channels reaches 0.5-1.8 gm3, in open areas of the delta front - 0.5-0.8 gm, in the coastal areas of the delta front islands - 0.1-0.3 gm. Peak development phytoplankton during the flood period is replaced by a significant decline, most often occurring in the second half of June,

With the establishment of summer-autumn low water, the greatest differentiation is observed in the spatial distribution of phytoplankton. The distribution of phytoplankton during this period is shown in Fig. 3.2.1st, using the example of August 2000. In channels, the biomass of phytoplankton increases, while the number of species decreases. Typically, the dynamics of phytoplankton development during the summer-autumn low-water period has a multi-peak character; during peaks, the algae biomass increases to 2.0-4.0 gm35 in some years reaching higher values. Thus, in 1997, at the end of July, the phytoplankton biomass reached 16.5 gm". Algae of the Baclariophyta department dominate, the biomass of which is usually about 85-95% of the total value. In this case, the main share falls on centric diatoms due to the development of algae of the genus Aulacosira (A. gmnulata f. granulata, Aulacosira sp.) and Sceleionema (S. subsalsum). Also, the second half of summer marks the growing season of blue-green algae, primarily Aphanizomenon flos-aqua and Microcystis aeruginosa, in some years the quantitative development of which can be significant. In open areas of the avandelta, the biomass of phytoplankton decreases by the end of August to 0.03-0.3 gm." At the same time, the share of Baclllariophyta in the total biomass of phytoplankton increases significantly due to a decrease in the biomass of algae of other departments. The value of phytoplankton biomass at various stations of the coastal sections of the avandelta islands varies significantly, which is due to the diversity of biotopes and the influence of local factors. At most stations, high values ​​are observed - in the range of 0.5-4.5 hm3, in some cases reaching higher values. The maximum observed biomass of coastal phytoplankton was 27.5 ru J. The distribution of species composition is mosaic.

Relationship between the spatial distribution of phytoplankton and hydrological factors and the phenomenon of phytoplankton sedimentation in the delta front

With the dynamic interaction of the river and the receiving reservoir within the estuary area of ​​the river, river waters spread and the flow rates at the seaside attenuate (River deltas, 1986). In the shallow zone of the Volga estuary nearshore, with a planar flow, the flow rates of the currents initially sharply decrease at the mouth of the watercourse at the sea edge of the delta (at the river mouth “microbar”), and then almost do not change until the water leaves the sea bar (Ustevaya.,., 1998) . In the channels, current velocities during the flood period are 0.51-1.30 ms"1, during the low-water period - 0.08-0.36 ms"1, in the delta front these figures are respectively 0.25-0.62 ms"1 and 0.04-0.12 m "s"[ (Moskalenko, 1965). Such a significant change in flow rates as it moves from the channels to the delta front is one of the main factors determining the change in the composition and abundance of phytoplankton. With the establishment of summer-Oseppei low water, a decrease in these indicators is observed as one moves from the mouths of the channels to the open areas of the delta front due to the degradation of the river phytoplankton complex, the core of which during this period is primarily representatives of the genera Aulacosira and Melosira.

There are a large number of works that note that for the development of many diatoms, flow and turbulent mixing are necessary and are of great importance for maintaining a suspended state (Lund, 1966; Oksiyuk, 1973; Kiselev, 1980; Oksiyuk, Stolberg, 1988; Hydrobiology. ..,1990, etc.). According to K.A. Guseva (Guseva, 1968), many planktonic diatoms of fresh water, in particular the genus Melosira, do not have reliable adaptations for soaring, so they need continuous movement of water.

We conducted laboratory experiments in cylinders filled with water taken from a channel during the summer-autumn low-water period, according to the decrease in chlorophyll a in plankton over time during settling. The composition of phytoplankton was typical for this season - the main share was made up of centric diatoms, primarily the genera Aulacosira and Melosira (93%). The values ​​obtained in laboratory conditions were reduced to a layer height equal to the average depth of the delta front. The experimentally obtained curve of the kinetics of the loss of chlorophyll a during sedimentation was compared with the curve of the decrease of chlorophyll a in the delta front as one moves from the mouths of the channels towards the sea (Fig. 3.4.1). For comparability of results, data on the content of chlorophyll a in the delta front were presented taking into account the distance of the stations from the mouths of the channels and the time of passage of water masses over this distance.

As can be seen in Fig. 3.4.1, the nature of the decrease curves of chlorophyll a in plankton in experiment and in natural conditions is similar, which indicates the significant role of the factor of gravitational sedimentation of phytoplankton in the delta front. At the same time, the decrease in chlorophyll a in the experiment occurs more slowly than in the delta front. First of all, this may be explained, in addition to the gravitational sedimentation of phytoplankton in the delta front, by its filtering and consumption by benthos and periphoton organisms.

Thus, in the lower reaches of the Volga delta, phytoplankton organisms, together with water masses, are carried out from the channels to the delta front. Here there is a rapid change in the species composition of phytoplankton and the transformation of river planktonic complexes into delta-front ones. At the same time, typical river forms disappear from the plankton composition or their number decreases. The biomass of phytoplankton decreases, the content of chlorophyll a in plankton and the intensity of photosynthesis decrease as a result of the fact that in conditions of shallow water, strong overgrowth of aquatic vegetation and a sharp slowdown in flow, subsidence and death occur

It is known that planktonic organisms, especially phytoplankton, are specific concentrators of many chemical elements; they play a significant role in their biogenic migration (Telitchenko et al., 1970; Khobotyev, Kapkov, 1972; Varenko, Misyura, 1985). Sedimentation of river phytoplankton in the delta front should lead to the release of some of the chemical elements that were previously part of planktonic organisms or their entry into the soil along with settling plankton.

Recently, the assessment of the primary productivity of water bodies has been carried out, in addition to traditional methods, by determining the value of chlorophyll a in plankton. This method is used for environmental monitoring in all types of water bodies - both freshwater and marine. Indicators of chlorophyll a content are used to determine the trophic status of water bodies (Vinberg, 1960; Pyrina, 1965a; Mineeva, 1979; etc.). The concentration of chlorophyll a is used to determine the biomass of algae (Vinberg, 1960; Elizarova, 1975; 1993). Data on the content of chlorophyll a in plankton serve to determine non-organic primary production of phytoplankton and model these processes (Pyrina, Elizarova, Nikolaev,! 973; Makarova, Zaika, 1981; etc.). To characterize water quality, the chlorophyll-water transparency ratio is used (Bulyok, 1977; 1983). The accumulation of chlorophyll a in the volume of water serves to assess the degree of eutrophication of water bodies and their sanitary and biological condition.” A positive correlation was found between the distribution of chlorophyll a by carotenoids and photosynthesis. Based on the ratio of chlorophyll a and carotenoids, the physiological state of the algae population and the state of the environment can be assessed (Margalef, I960; 1967; Watson, Osborne, 1979; Davydova, 1983).

Thus, the value of chlorophyll a content in water is an integral characteristic of the biological productivity of water bodies on the autotrophic level, an important indicator of the state of aquatic ecosystems

Spatiotemporal distribution of chlorophyll a and other photosynthetic pigments of plankton in the delta front

The distribution of chlorophyll a and other photosynthetic pigments of plankton in the water area of ​​the delta front is characterized by a large mosaic pattern. Seasonal changes in the spatial distribution of chlorophyll a, despite some differences in different years, are generally characterized by the general nature of the dynamics. The seasonal dynamics of the content of phytoplankton pigments in different areas of the delta front is presented in Table. 4.2.1,4-2.2, 4-2.3,4,2-4 In the spring, before the onset of floods, in the delta front, the concentration of chlorophyll a in different years was in the range of 4.7-91.7 mg m"3 "At most stations, the chlorophyll a content was relatively uniform and ranged from 9.6 to 12.7 mg-m." Higher concentrations of chlorophyll a were noted in the coastal areas of the delta-front islands - up to 31.2 mg-m" and in local areas in the coastal areas of islands with reduced water exchange - up to 91.7 mg-m". In the channels at this time, the amount of chlorophyll a was significantly lower and amounted to 2.3 - 3.5 mgm3. A significant excess of the concentration of chlorophyll a in the plankton of the delta front over the content of chlorophyll a in the channels of the above-water delta in the spring is due to the earlier development of phytoplankton in the delta front. in conditions of better warming up and increased water temperature. The difference in water temperature in the channels and the delta front during this period can reach more than 15 degrees - in the channels the water temperature does not exceed 8.0-12.0 C, in the delta front the water can warm up to 17.5-20 ,0C in open areas and up to 25.0-27.5C in the coastal areas of the islands. The content of additional pigments during this period was low. The concentration of chlorophyll b averaged 7-14% of the total amount of chlorophylls, chlorophyll c - 11-16%. The concentration of carotenoids ranged from 6.1 to 80.9 mSPU-m"3 and at the vast majority of stations surveyed slightly exceeded the concentration of chlorophyll o. The observed pigment ratio values ​​varied over a fairly wide range - from 0.8 to 1.6, but were low at most of the stations surveyed.

During the spring-summer flood period, the concentration of chlorophyll a in the delta front was in the range of 1D-22.9 mg-m"3, the average values ​​were 5.8-14.7 mg-m"3. The highest values ​​of chlorophyll a were observed in open areas of the delta front, largely due to the removal of plankton from the channels, which was facilitated by high flow velocities. In the channels at this time, an increase in the concentration of chlorophyll a was observed to 9.B-mgm - 22.8 MG Ї G\ The lowest values ​​were noted in the coastal areas of the islands, where, compared with the previous period, the concentration of chlorophyll a decreased by 2-6 times In general, the distribution of chlorophyll a in the fore-delta during the spring-summer flood period is characterized by the greatest uniformity.

The content of chlorophylls d and c relative to the total amount of chlorophylls in the delta front ranged, respectively, from 0 to 14.1% and O to 18.3%. The pigment ratio ranged from 0.9 to 1.6, the highest values ​​were observed in areas open delta front. The concentration of carotenoids ranged from 079 to 21.0 mSPU-m"3 and was generally close in value to the concentration of chlorophyll a.

During the decline of the flood, the concentration of chlorophyll a in the open areas of the delta front decreased, in the coastal areas of the islands it changed slightly. During the low-water period (July, August), the concentration of chlorophyll a was generally low, the average concentration was 3.6-6.3 mg-m3. In local areas in the coastal areas of the islands, the concentration of chlorophyll a varied within significant limits and could reach very high values ​​(up to 97?2 mgm"3). The content of chlorophyll bis ranged from 0 to 27.8 mgm"3 and from 0 to 29.4 mg-m"3. The share of chlorophyll b from the total amount of chlorophylls was 0 - 19D%, chlorophyll c - 0-21.7%. The concentration of carotenoids averaged 4.4-38.4 mSPU-m" and on Most stations exceeded the concentration of chlorophyll a. The pigment ratio varied within 0.8 - 2.0, the highest values ​​were observed in the open delta front, where at that time there was inhibition in the development of phytoplankton. In the channels during this period, the concentration of chlorophyll a was generally higher.

In autumn, in September and October, in most of the water area of ​​the fore-delta the content of chlorophyll a was in the range of 1.5-13.3 mg-m" 9 and in the coastal areas of the islands it was significantly higher - 9.2-113.2 mg-m "3. The general picture of the spatial distribution of phytoplangsgon pigments was generally similar to that observed at the end of summer.

The spatial distribution of chlorophyll a is shown in Fig. 4.1 L. (using the example of 2000).

Thus, the spatial distribution of plankton photosynthetic pigments in the delta front was characterized by great unevenness and varied with the seasons.

The highest content of chlorophyll a in the delta front was observed in the spring, before the onset of the flood, especially in the coastal areas of the islands, when, with an increase in solar radiation in shallow water conditions, a significant warming of the water occurs, significantly greater than in the channels.

With the onset of high water, the concentration of chlorophyll a in the coastal areas of the islands decreased, and in the open delta front it changed slightly. During this period, the most uniform spatial distribution of chlorophyll a was observed in the channels of the above-water delta and in the avandelta, as a result of the fact that high water levels and high flow speeds, on the one hand, provide relatively uniform conditions, and on the other hand, transit demolition of phytoplankton occurs. During the summer-autumn low-water period in the delta front, the content of chlorophyll a is generally low, with the exception of local areas of the coastal areas of the islands.

Efficiency of solar radiation energy utilization during plankton photosynthesis

The amount of solar radiation energy falling per unit surface of a reservoir, accumulated as a result of the photosynthetic activity of plankton in the water column under this area, expressed as a percentage, characterizes the efficiency of utilization of solar radiation energy by plankton. This indicator well reflects the degree of development of phytoplankton and shows the rate of new formation of organic matter. In contrast to the value of primary production, the efficiency indicator of solar radiation energy utilization does not depend on illumination, which is primarily determined by weather conditions during the period of experiments and is often a hindrance when comparing results. Therefore, the efficiency of light utilization by plankton can often be a more adequate indicator of the productivity of water bodies than the actual value of primary production (Pyrina, 1967).

The question of the efficiency of utilizing the energy of sunlight during plankton photosynthesis was considered in detail by G.G. Vinberg (I960), who noted that the maximum values ​​of solar energy utilization were obtained by Oswald (Oswald et al., 1957; cited by Vinberg, 1960) in special conditions of “oxidizing ponds”, where they averaged 2-4 % of the total radiation energy for the season. In natural reservoirs, these values ​​are much lower. As an example of the high degree of utilization of solar energy, G.G. Vinberg cites the efficiency of radiation use for lakes Chernoe and Kosino (according to his own data in 1937) at the level of 0.4% per year and 0.77% - maximum per day and for Lake Zölleröd - 0.77% maximum per day (Stccraann Nielsen , 1955; cited in Vinberg, 1960). High results were obtained by I.L. Pyrina (1967) for the Volga reservoirs (Ivankovsky, Rybiysky and Kuibyshevsky) - on average for the growing season 0.2-0.5% and maximum daily 1.17-2.14% of visible radiation energy. If we take into account that the authors accepted that visible radiation makes up 50% of the total, then these values ​​will respectively be OD-0.25% and 0.58-1.07% of the total solar radiation. In the Sheksninsky Reservoir, the average efficiency of solar energy utilization during the growing season was below 0E08-0D 1% (Mineeva, 2003). As an example of the low efficiency of solar radiation energy utilization, G.G. Vinberg cites Lake Beloe, where this value did not exceed 0.04% and for the year amounted to 0.02% of the energy of the total radiation. Even lower values ​​were obtained by L.G. Kornevoy and N.M. Mshieeva (1986) when studying reservoirs with high turbidity. The maximum values ​​they obtained for the efficiency of solar energy utilization for the Vytegorsky and Novinkinsky reservoirs, the Kovzha River at the mouth and near the village of Annensky Most, respectively, were 0.06%; 0.02%; 0.05% and 0.007%, and the minimums are 0.02%, 0.001%, 0.006% and 0.001%.

According to our data, in the watercourses of the lower reaches of the Volga delta, the efficiency of using solar radiation energy during the growing season averaged 0.04-0.06% of the total or 0.10-0.12% of photosynthetic active radiation. The efficiency of solar energy utilization by phytoplankton varied greatly by season (Table 5.2.1.) The highest values ​​were observed at the peaks of phytoplankton development in May and July-August, when the average monthly efficiency of utilization of total solar radiation energy reached 0.05-0.08% Low values ​​of the efficiency of solar energy utilization are characteristic of periods of low intensity of phytoplankton photosynthesis - early spring and late autumn, when the efficiency of utilization of the total energy of solar radiation usually did not exceed 0.03-0.04%. In June, with a decrease in the primary production of plankton, a rather low efficiency of utilization of the total energy of solar radiation was also observed, which, apparently, is associated with a lack of nutrients during the decline of the flood.

Thus, we can conclude that the lower reaches of the Volga delta are characterized by relatively low values ​​of the efficiency of solar radiation energy utilization during plankton photosynthesis. The low efficiency of solar energy utilization by plankton in channels is largely due to the high content of suspended particles in the water, which creates low water transparency and causes a significant weakening of penetrating radiation with depth. The dependence of the degree of use of light in a reservoir on the transparency of the water was noted by Comita and Edmondson (1953). The turbulent movement of water masses in the channels is also of great importance, which creates constant mixing, as a result of which one or another part of the cells is always algae carried beyond the euphotic zone remain in the dark in a state of so-called “light starvation” (Sorokin, 1958).

A close relationship was observed between monthly indicators of the efficiency of solar radiation energy utilization and the concentration of chlorophyll “a” in the plankton of the channel (Fig. 5.2.1.).