Phytoplankton Primary Production Research Articles

Accurate Acquisition of Initial Fluorescence in Phytoplankton Primary Productivity Measurement by Fluorescence Dynamics Method

Accurate Acquisition of Initial Fluorescence in Phytoplankton Primary Productivity Measurement by Fluorescence Dynamics Method

Primary production research in the Adriatic Sea

Primary production in the Adriatic Sea has been investigated for many years, however, a comprehensive systematic review of the literature is lacking. This paper aims to fill this gap by providing a thorough overview of all conducted studies, emphasising the methodologies employed, and comparing representative values. The first section introduces the history of primary production measurements and gives insights into the Adriatic basin’s hydrography and its impact on primary producers and their rates of production. The second section provides an overview of productivity across the geographical regions of the Adriatic Sea. The Middle Adriatic Sea stands out as one of the rare locations in the world where in situ measurements of primary production have been systematically conducted since the 1960s and are ongoing. This data has only recently been synthesised and corrected for overestimates using a modelling approach. The final section is an overview of all primary production studies supported with comprehensive summarising tables. Most of the data concerns phytoplanktonprimary production estimated by 14C method. Annual primary production in the Northern and Middle Adriatic ranges between 87.4–260.0 g C m-2 y-1, and 70.0–177.4 g C m-2 y-1, respectively. Southern Adriatic Sea is the least investigated, and only daily estimates are available (236–374 mg C m-2 d-1). The purpose of this review is to highlight the significance of measuring primary production in the Adriatic Sea and the need for future research that will contribute to a more comprehensive understanding of the basin’s productivity.

Factors affecting abundance and primary productivity of phytoplankton in a wetland ecosystem of Bangladesh

Wetlands are the most productive, economically important and hydrologically variable ecosystems. In this study, the abundance of phytoplankton and its primary productivity were evaluated in Dingapota Haor of Bangladesh. A total of 41 phytoplankton genera belong to Chlorophyceae (15), Bacillariaophyceae (14), Cyanophyceae (8) and Euglenophyceae (4) were recorded whereas Bacillariaophyceae (37.02%) was the most dominant. The highest cell density (22.71×104 cell L–1) was recorded in pre-monsoon. Diversity indices were also significantly higher in pre-monsoon. The species diversity, evenness and richness varied from 2.51–3.79, 0.57–0.90 and 4.65–7.50 respectively. Difference in phytoplankton assemblage with an overall average dissimilarity value of 52.56 % was recorded. Cyclotella (3.60%), Bacillaria (3.13%), Volvox (2.95%), Spirulina (2.92%) and Euglena (2.88%) were the five most contributory species to the seasonal variation. Gross Primary Production, Net Primary Production and Community Respiration values ranged from 0.90–2.49, 0.68–1.60 and 0.35–0.89 mgCm–3day–1 respectively. Alkalinity and Chl-a showed significant positive correlation with GPP, NPP and CR. Pre-monsoon was the most productive phase whereas the monsoon season was the least productive. The current study produced valuable baseline data that will aid in the formulation of wetland conservation and management strategies.

Influence of circulation processes on cyanobacteria bloom and phytoplankton succession in the Baltic Sea coastal area

Many studies related to the influence of eddies on the primary production chain of marine ecosystems have been conducted; however, this effect tends to be regionally specific, especially in coastal dynamic waters. In the Baltic Sea, mesoscale and submesoscale eddies are a ubiquitous feature of water circulation during summer, when diazotrophic cyanobacteria blooms occur in surface waters due to the excess of phosphorus in seawater. Climatic change may increase the frequency and duration of these negative events in the marine ecosystem. We examined the taxonomic composition, abundance, and primary production of phytoplankton in the southeastern Baltic Sea during the occurrence of the packed eddy system at the end of the abnormally warm summer of 2018. Massive cyanobacteria growth was observed in the plume of the eutrophic Vistula Lagoon in the Gulf of Gdansk. The only species diazotrophic Dolichospermum flos-aquae ((Bornet & Flahault) P. Wacklin, L. Hoffmann & Komárek, 2009) vegetated along the western coast of the Sambia Peninsula. Its colonies reached the highest biomass nearby the dumping site of the Amber Mining Plant in Yantarny, Kaliningrad Region, Russia. The cyanobacteria colonies dispersed in the outgoing jet of a relatively warm eddy dipole. Chrysochromulina spp. (Lackey, 1939) was dominant in these nitrogen-rich waters. In contrast, cryptophyte species dominated in the relatively cold waters of the dipole anticyclone that resulted in a fourfold decline in primary production. The decrease in the number of mobile phytoplankton species was revealed within the “old” eddies near the northern coast of the Sambia Peninsula and the Curonian Spit. Meanwhile, species of the spring–autumn complex Coscinodiscus granii (Gough, 1905), Peridiniella catenate ((Levander) Balech, 1977) and other developed in the community. This implies that the appearance of eddies can cause phytoplankton succession in the coastal area. The mechanism of their influence was similar to the action of other physical factors perturbing a relatively stationary environment. Capture of cyanobacterial colonies by eddies led to an improvement of the ecological situation in the area, as cyanobacteria transported their biomass outside the coastal area. However, the opposite direction processes obviously were the deterioration of light conditions, increased water turbidity, and organic matter concentration.

Phytoplankton primary production in Chascomus pond (Provincia de Buenos Aires, Argentina)

In situ phytoplankton primary production in Chascomús pond (eutrophic Pampasic “laguna”) was studied by the oxygen method (light and dark bottle) between.January 1984-January 1985. Valúes obtained ranged from37,9 to 981,6 mg C • m-1 • d-1. Factors influencing it, as suspended particulate matter and hydrological changes, are discussed. Parallel determinations of the artificial light photosynthesis response proved to be useful,almostqualitatively under the experimental conditions applied, to follow the behaviour obtained by incubations in natural environment.

INFLUENCE OF RIPARIAN FOREST AND TEMPERATURE ON PRIMARY PRODUCTION OF TROPICAL STREAMS

Primary production is a key feature for the functioning of aquatic ecosystems. The trophic state of the streams reflects this primary production and is influenced by local limnological variables and level of integrity of the watershed. Thus, in this study, habitat integrity index (HII) and physical, chemical, and biological parameters of tropical streams were sampled in two sub-basins to understand the functioning of these ecosystems. We hypothesized that the variables association to the environmental integrity should determine the primary production in the streams. Because of the similar land use in the sub-basins (ex.: agriculture and livestock) they will show similar limnological variables. To identify how the streams differed in relation to their limnological characterization and the HII, we performed a Principal Component Analysis (PCA). The association between variables was assessed by Pearson's correlation analysis. To identify the difference between the two basins, a Student's Test was performed. The best predictors of primary production were determined using a multiple regression analysis with the Akaike selection criteria. The concentration of chlorophyll-a in the surface water indicated that the tropical streams sampled have, in general, low concentrations of nutrients, except for some more urban points. The variables that most differed among streams were blue-green cells/ml, pH, conductivity, and width of the riparian forest. Only redox potential and pH differed between the two watersheds. Temperature, blue-green cells/ml and width of the riparian forest were the variables that best predicted the phytoplankton primary production of watercourses in both watersheds. In this study we reinforce the importance of temperature in aquatic productivity, even more present in the face of climate change, which, added to deforestation, increases the surface area of sunlight in water courses, increases primary productivity and the eutrophication process.Keywords: blue-green algae; chemical variables; chlorophyll-a; HII; phytoplankton.

Anomalous trend of chlorophyll-a as a response to mesoscale phenomena in a Brazilian oligotrophic ria

Saco do Mamanguá is a tropical Brazilian ria characterized by low nutrient availability and subject to seasonal thermocline, which is mainly influenced by the intrusion of South Atlantic Central Water (SACW) on the continental shelf. Sampling was performed in summer (2014, 2015) and spring (2017). The dissolved inorganic and organic nutrients (nitrogen [N] and phosphorus [P]), along with chlorophyll-a (Chl-a), were evaluated to characterize this area. As a result, the general trophic condition of Saco do Mamanguá is a meso-oligotrophic ria with low Chl-a concentrations. Due to the presence of an atmospheric phenomena that causes an extremely dry period during the summer of 2014, a strong thermocline was observed in the water column which was associated with high Chl-a concentrations (median of 6.14 mg m−3). These values were much higher than those observed during the summer of 2015 and in the spring of 2017 (median of 1.03 mg m−3). The dissolved inorganic nutrients presented low values in all studied periods with concentrations of nitrate (0.00–0.20 μmol L−1) and phosphate (0.00–0.20 μmol L−1). A wide range of dissolved organic compounds were also observed, as shown by the presence of dissolved organic carbon (DOC), which varied from 63 to 212 μmol L−1; dissolved organic nitrogen (DON), which varied from 2.97 to 12.92 μmol L−1; and dissolved organic phosphorus (DOP), which reached a maximum value of 0.63 μmol L−1. DON and DOP represented at least 50% total dissolved N and P. In this region, the biogeochemical cycles of N and P could ensure the availability of regenerated nutrients from organic sources to support primary production of phytoplankton.

Parameterization of Water Transparency in Natural Water Bodies

A new parameterization is presented to describe the space and time variations of Secchi depth depending on the integral phytoplankton biomass and surface water temperature. The parameterization was verified against field data in lakes with different types of physiographic and chemical–biological characteristics—from deep oligotrophic northern regions of Lake Ladoga to shallow hypereutrophic Pskovskoe Lake. The results of verification show that the new parameterization can be used for solving a wide range of either hydrothermodynamic or hydrobiological problems. In particular, in the simulation of the thermal regime of water bodies, the proposed parameterization can be used to evaluate the coefficient of extinction of solar radiation. In the development of models to describe aquatic ecosystem functioning, the new parameterization can be used to evaluate the thickness of the trophogenic layer and phytoplankton primary production.

Spatiotemporal patterns and drivers of phytoplankton primary productivity in China's lakes and reservoirs at a national scale

Spatiotemporal patterns and drivers of phytoplankton primary productivity in China's lakes and reservoirs at a national scale

Assessment of satellite-based Net Primary Productivity models in different biogeochemical provinces over the northern Indian Ocean

ABSTRACT The biological productivity in the oceanic ecosystem plays a vital role in the global carbon cycle and energy flow in the oceanic food chain. Therefore, proper monitoring of phytoplankton primary production in the ocean is essential to understand the role and responses of aquatic ecosystems to global climate change. Its quantification is also important for higher trophic-level studies and sustainable ecosystem management. The advent of satellite technology has provided an opportunity to retrieve Net Primary Productivity (NPP) at high spatial and temporal resolution. However, for efficient utilization of satellite NPP it is imperative to assess the models for their accuracy and variability. The present study described NPP estimated from MODIS-Aqua satellite data (2003–2021) using five models (VGPM, Eppley-VGPM, CbPM, CAFE, and SABPM) and their variability in the four biogeochemical provinces (ARAB, MONS, INDW and INDE) in the northern Indian Ocean. The temporal variability indicated all models exhibit seasonal variability in ARAB and INDW with two prominent peaks during peak southwest monsoon (June-August) and winter monsoon (December-January). However, there was significant difference in the magnitude. The seasonal peak was primarily due to increase in NPP due to summer upwelling and winter mixing. The spatially averaged diversity index indicated maximum variability in INDW (74.6–77.1%), followed by INDE (77.2–78.0%), ARAB (77.2–78.4%), and MONS (78.6–78.9%). The satellite retrieved NPP by various models showed maximum diversity in the region above 15°N and west of 60°E in AS and 20°N and east 90°E in the BoB indicating a significant influence of discharge from perennial rivers resulting in poor performance of the models in these regions. The variability of other models was then assessed with respect CbPM as the model was known to perform better. The Eppley-VGPM showed a maximum (55%) and SABPM showed a minimum (11%) Mean Absolute Percentage Difference with respect to CbPM. The long-term spatio-temporal and quantifiable variability between the NPP models, and biogeochemical provinces, indicated that the study provided useful information on the selection and utilization of an appropriate model for future sustainability and climate change studies.

Primary Production in the Kara, Laptev, and East Siberian Seas.

Understanding of the primary production of phytoplankton in the Kara Sea (KS), the Laptev Sea (LS), and the East Siberian Sea (ESS) remains limited, despite the recognized importance of phytoplankton in the Arctic Ocean. To address this knowledge gap, we conducted three NABOS (Nansen and Amundsen Basins Observational System) expeditions in 2013, 2015, and 2018 to measure in situ primary production rates using a 13C-15N dual-tracer method and examine their major controlling factors. The main goals in this study were to investigate regional heterogeneity in primary production and derive its contemporary ranges in the KS, LS, and ESS. The daily primary production rates in this study (99 ± 62, 100 ± 77, and 56 ± 35 mg C m-2 d-1 in the KS, LS, and ESS, respectively) are rather different from the values previously reported in each sea mainly because of spatial and regional differences. Among the three seas, a significantly lower primary production rate was observed in the ESS in comparison to those in the KS and LS. This is likely mainly because of regional differences in freshwater content based on the noticeable relationship (Spearman, rs = -0.714, p < 0.05) between the freshwater content and the primary production rates observed in this study. The contemporary ranges of the annual primary production based on this and previous studies are 0.96-2.64, 0.72-50.52, and 1.68-16.68 g C m-2 in the KS, LS, and ESS, respectively. Further intensive field measurements are warranted to enhance our understanding of marine microorganisms and their community-level responses to the currently changing environmental conditions in these poorly studied regions of the Arctic Ocean.

Microbial food web changes induced by terrestrial organic matter and elevated temperature in the coastal northern Baltic Sea

Climate change has been projected to cause increased temperature and amplified inflows of terrestrial organic matter to coastal areas in northern Europe. Consequently, changes at the base of the food web favoring heterotrophic bacteria over phytoplankton are expected, affecting the food web structure. We tested this hypothesis using an outdoor shallow mesocosm system in the northern Baltic Sea in early summer, where the effects of increased temperature (+ 3°C) and terrestrial matter inputs were studied following the system dynamics and conducting grazing experiments. Juvenile perch constituted the highest trophic level in the system, which exerted strong predation on the zooplankton community. Perch subsequently released the microbial food web from heavy grazing by mesozooplankton. Addition of terrestrial matter had a stronger effect on the microbial food web than the temperature increase, because terrestrial organic matter and accompanying nutrients promoted both heterotrophic bacterial production and phytoplankton primary production. Moreover, due to the shallow water column in the experiment, terrestrial matter addition did not reduce the light below the photosynthesis saturation level, and in these conditions, the net-autotrophy was strengthened by terrestrial matter enrichment. In combination with elevated temperature, the terrestrial matter addition effects were intensified, further shifting the size distribution of the microbial food web base from picoplankton to microphytoplankton. These changes up the food web led to increase in the biomass and proportion of large-sized ciliates (&amp;gt;60 µm) and rotifers. Despite the shifts in the microbial food web size structure, grazing experiments suggested that the pathway from picoplankton to nano- and microzooplankton constituted the major energy flow in all treatments. The study implies that the microbial food web compartments in shallow coastal waters will adjust to climate induced increased inputs of terrestrial matter and elevated temperature, and that the major energy path will flow from picoplankton to large-sized ciliates during the summer period.

Regulation of a surface chlorophyll hotspot by wind-driven upwelling and eddy circulation in the Santa Barbara Channel, Southern California

While most of the U.S. Pacific coast is dominated by strong wind-driven upwelling in the spring and regular seasonal cycles of phytoplankton primary production, the Southern California Bight has weak intermittent wind-driven upwelling and low phytoplankton concentrations due to its irregular sheltered coastline. However, the Santa Barbara Channel (SBC), located in the northern Southern California Bight, contains an anomalous hotspot of phytoplankton biomass. We use 3D ocean circulation and particle tracking models, an empirical temperature-nitrate relationship, and satellite observations of surface chlorophyll from 1998 to 2007 to determine how wind-driven upwelling and cyclonic eddy circulation govern phytoplankton dynamics in the SBC. Our findings show that elevated surface chlorophyll in the spring is driven by the coupling of wind-driven upwelling and cyclonic eddy circulation and requires the presence of both high nitrate from wind-driven upwelling and prolonged residence times from eddy circulation. Long residence times, created by persistent cyclonic eddy circulation, allow nitrate transported into the surface layer by wind-driven upwelling to be retained in the SBC long enough to meet the required timescales for phytoplankton nutrient uptake and accumulation, overcoming the typically weak wind-driven upwelling of the Southern California Bight. Typical spring upwelling periods (SUPs) have high levels of surface chlorophyll, which are produced by the balanced coupling of upwelling strength and cyclonic eddy circulation. For two years of our study, 1998 and 1999, the SUP did not correlate with elevated surface chlorophyll. Corresponding to a strong El Niño event, the 1998 SUP had exceptionally weak wind-driven upwelling, which did not produce sufficient levels of nitrate to stimulate elevated surface chlorophyll. For the 1999 SUP, a strong La Niña event produced unusually strong wind-driven upwelling, which resulted in very high levels of nitrate, but suppressed eddy circulation and residence times to the point where phytoplankton biomass could not accumulate in the SBC. These anomalous SUPs illustrate that when wind-driven upwelling is too strong or too weak, the balance between wind-driven upwelling and cyclonic eddy circulation is disrupted, resulting in a dramatic reduction of surface chlorophyll, which may become more frequent with climate-driven upwelling changes in the future.

Increased sea ice melt as a driver of enhanced Arctic phytoplankton blooming.

Phytoplankton primary production in the Arctic Ocean has been increasing over the last two decades. In 2019, a record spring bloom occurred in Fram Strait, characterized by a peak in chlorophyll that was reached weeks earlier than in other years and was larger than any previously recorded May bloom. Here, we consider the conditions that led to this event and examine drivers of spring phytoplankton blooms in Fram Strait using in situ, remote sensing, and data assimilation methods. From samples collected during the May 2019 bloom, we observe a direct relationship between sea ice meltwater in the upper water column and chlorophyll a pigment concentrations. We place the 2019 spring dynamics in context of the past 20 years, a period marked by rapid change in climatic conditions. Our findings suggest that increased advection of sea ice into the region and warmer surface temperatures led to a rise in meltwater input and stronger near-surface stratification. Over this time period, we identify large-scale spatial correlations in Fram Strait between increased chlorophyll a concentrations and increased freshwater flux from sea ice melt.

The influence of biochemical parameters on primary production in the Gulf of Gdańsk region: A model study

Understanding the changing levels of biochemical parameters and the factors that influence them throughout the seasons is crucial for comprehending the dynamics of marine ecosystems. It also helps us identify potential threats that could harm their condition, aiding decision-making processes related to their protection. This study focuses on examining the variations in nutrients (such as nitrates, phosphates, and silicates), dissolved oxygen, and phytoplankton within the Gulf of Gdańsk. Additionally, we analyze the primary production process at three representative locations. To achieve this, we used data from the EcoFish biochemical numerical model. To ensure the model's accuracy, we compared its results with in situ data from the ICES database. The comparison revealed high correlations and minimal errors. Furthermore, we investigated how limiting factors impact primary phytoplankton production and demonstrated how the intensity of spring diatom blooms influences the nature of cyanobacterial blooms in the summer.

THE RELATIONSHIP OF PRIMARY PRODUCTIVITY OF PHYTOPLANKTON WITH OCEANOGRAPHIC PARAMETERS IN THE WATERS OF LUBUK GAUNG SUB-DISTRICT, SUNGAI SENIN DISTRICT, DUMAI

The waters of Lubuk Gaung Village, Sungai Sembilan District are areas that are widely used as transportation routes. Activities in these waters will cause environmental pollution, which affects the life of phytoplankton. The purpose of this study was to determine the relationship between the primary productivity of phytoplankton with oceanographic parameters in the waters of Lubuk Gaung Village, Sungai Sembilan District, Dumai. The method used is the survey method to determine the research station and the in situ method for measurement and sampling of oceanographic parameters. The results obtained are Oceanographic parameters from the three research stations, namely Brightness = 30 – 49 cm, Turbidity = 47.4 – 58.4 FTU, TSS = 124 – 209 mg/L, and BOD = 0.408 – 1.224 mg/L. The average value of primary productivity of the waters ranged from 48.07 to 79.69 mgC/m3/day. The value of primary productivity at station II is categorized into Oligotrophic, namely low waters. Stations I and III are categorized into mesotrophic waters, namely medium waters. The relationship between brightness, turbidity, and TSS with primary productivity has a very strong and positive (unidirectional) correlation value. The relationship between BOD and primary productivity has a very strong and negative (opposite) correlation.

Lateral Advection of Particulate Organic Matter in the Eastern Indian Ocean

AbstractThe Argo Abyssal Plain (AAP), south of Java and northwest of Australia in the tropical eastern Indian Ocean, is an oligotrophic region (low in chlorophyll and nutrients), downstream of the Indonesian throughflow. The processes that supply nitrogen to the AAP and support ecosystem production are unknown. Here we quantified lateral advection of particulate organic matter (POM) and the role of this advected POM in supplying new nitrogen (i.e., allochthonous nitrogen supply) to the mixed layer of the AAP using 14 yr of remotely sensed data, combined with sampling undertaken on a research cruise in February 2022. Our results indicate that the average net primary productivity of phytoplankton in this offshore oligotrophic region is 98.5 Gg C d−1 and that lateral advection transports 1.21 Gg C d−1 of particulate organic carbon (POC) into the region. We find that lateral advection of POM within the mixed layer supplies an annual average of 12% (95% C.I. = 5.2%–49%) of allochthonous “new” nitrogen supporting phytoplankton productivity, if regenerated to nutrients through microbial processes. Accounting for lateral transport in the deep euphotic zone, lateral transport supplies an average of 32% (10%–&gt;100%) of new nitrogen, although this calculation is less certain due to inability to constrain subsurface POM fields. Our data suggest that lateral advection is a quantitatively important but not dominant source of nitrogen supporting new production. Overall, approximately half of the lateral transport is driven by transient eddies (mostly during winter) highlighting the importance of mesoscale circulation.

Chlorophyll response to wind and terrestrial nitrate in the western and southern continental shelves of the Gulf of Mexico

In Mexico, 16 rivers directly discharge into the Gulf of Mexico. The Mexican rivers and those coming from the United States generate large regions in which phytoplanktonic primary production possesses a seasonal component that is linked to these nutrient-rich freshwater inputs. In the present study, new simulated flow and daily nutrient data were obtained for the largest Mexican rivers. These data were integrated as forcings in a configuration of the hydrodynamic Coastal and Regional Ocean COmmunity model coupled to an N2PZD2 biogeochemical model. We present a 21 year simulation using two different configurations. The first included river forcing, and the second did not consider their influence. The results were validated with satellite images of the surface chlorophyll concentration and discussed with data presented in previous studies. The model was able to realistically reproduce the seasonal dynamics of primary production in the Gulf of Mexico based on the concentration and distribution of chlorophyll, both at the surface and in the water column. We found significant differences in the response of chlorophyll to the input of nitrate from the rivers between both model configurations. The largest and most evident in the northern region of the continental shelf followed by the Bay of Campeche and Tamaulipas-Veracruz shelves. Finally, using the configuration with the river forcing, the physical processes that influence the dynamics of chlorophyll concentration in the deep region and continental shelf of the gulf were determined. In the deep region, primary production was driven by vertical mixing induced by the passage of cold fronts during winter and mesoscale structures. On the continental shelf, such dynamics were driven by coastal upwelling and fluvial nutrient contributions.

Horizontal Heterogeneities of Functioning of Phyto- and Zooplankton in a Lake With Wind Currents

A hypothesis about the formation of horizontal heterogeneities of zooplankton and phytoplankton for the lake subjected to regular daily changes in wind currents has been tested. Formation of horizontal heterogeneities is based on a combination of low-amplitude vertical migration of zooplankton and epilimnion wind currents: surface currents, which bring water depleted in zooplankton to the downwind shore (in the direction in which the wind is blowing), and compensatory above-thermocline ones, which bring zooplankton-enriched water to the upwind shore (against the wind). The spatial separation of phytoplankton and zooplankton may result in the weakening of trophic links between these trophic levels. The hypothesis was tested in 2020 in the pelagic zone of Lake Shira (Khakassia, Russia), a brackish meromictic water body with simple bathymetry and a simple food web. The epilimnion horizontal heterogeneities were assessed using a survey across the lake by measuring biological and physical parameters with a submersible fluorimeter probe and a plankton net at 11 stations and recording the dynamics of wind speed and direction. Differences in the values of primary production, plankton destruction, and intensity of phytoplankton grazing by zooplankton near the downwind and upwind shores were estimated using the bottle method in 3 experiments. The experiments confirmed the expected differences in the functioning of the trophic cascade near the northeastern (more often upwind during the day and downwind at night) and south-southwestern (downwind during the day and upwind at night) shores. Namely, the concentration of chlorophyll a, the gross and net primary production of phytoplankton (estimated by bottle and fluorescent methods), and the daily intensity of zooplankton feeding (based on chlorophyll) were higher near the southern coast, while the biomass of net zooplankton and the respiration rate of the plankton community were higher near the northeastern shore, which coincided with the pattern of phyto- and zooplankton distribution over the lake according to the sampling data under similar weather conditions. The hypothesis was confirmed and supplemented by the data on the evening-night vertical migrations of zooplankton.

Environmental factors drive phytoplankton primary productivity in a shallow Lake

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