The long-term data (1996–2021) on the summer abundances of the dominant zooplankton species (cope... more The long-term data (1996–2021) on the summer abundances of the dominant zooplankton species (copepod Arctodiaptomus salinus (Daday, 1885), rotifers Brachionus plicatilis (Müller, 1786) and Hexarthra sp.) in saline Lake Shira were used to analyze the response of zooplankton to air temperature and a change in the circulation regime of the lake: breakdown and reestablishment of meromixis. All groups of zooplankton responded to prolonged summer elevated temperatures by increasing their abundance. During the breakdown of the stable stratification of Lake Shira (2015–2016), zooplankton abundance increased on average by a factor of two and amounted to 9×105 inds./m2 in the water column for copepods. That increase coincided with similar responses of other components of the lake’s mixolimnion ecosystem, whose biomasses increased approximately two-fold during that period. After the reestablishment of the meromixis, the abundance of zooplankton decreased to previous values. Thus, the abundance of zooplankton is largely determined by weather (the effect of temperature) and ecological factors (mixing regime).
The cladoceran Daphnia magna inhabits lakes with salinities up to 10 g L −1 . We compared the eff... more The cladoceran Daphnia magna inhabits lakes with salinities up to 10 g L −1 . We compared the effects of different salinities (up to 9 g L −1 ) on the survival, specific grazing rate, and size selective feeding of Daphnia females adapted to fresh or saline waters (3–4 g L −1 ). The freshwater population was more sensitive to high salinity (LC 50 = 5.3 g L −1 ), while the survival of the saline water population also decreased in fresh water. Freshwater population demonstrated a higher grazing rate in fresh water, while the saline water population had a higher grazing rate at the salinity above 3 g L −1 . A decrease in the grazing rate of the freshwater population was observed at the salinity above 4–5 g L −1 . Populations differed in food selectivity. The saline water population consumed particles of larger sizes than the freshwater population. The average size of phytoplankton particles grazed in fresh water was larger than in saline water. This size selective salinity-dependent grazing may be related to the dependence of the feeding efficiency of cladocerans on the viscosity of water and size of phytoplankton particles. Our results indicate that Daphnia populations adapted to a certain salinity can temporarily lose the ability to control phytoplankton because of salinity fluctuations.
Journal of Siberian Federal University. Biology, 2021
Salinity largely determines the species diversity and structure of the food web in lake ecosystem... more Salinity largely determines the species diversity and structure of the food web in lake ecosystems. Many studies have been focused on the salinity tolerance of various plankton species. There are fewer studies investigating the modifications in the food web interactions under the effect of salinity. An appropriate system for such studies is closely located lakes of different salinity. We took samples during the summer stratification and analyzed the physicochemical and biological characteristics of 20 lakes (salinity 0.1-35 g/l) in southern Siberia in order to provide general description of this system and to test a number of hypotheses about the effect of salinity on the structure of the food web. The analysis revealed two key factors structuring ecosystems of the studied lakes. The species composition of zooplankton was determined by salinity, with a decrease in the number of species and the transformation of the community from a diverse community of zooplankton (salinity up to 3 ...
The term meromixis was introduced more than 80 years ago to denote lakes that do not annually mix... more The term meromixis was introduced more than 80 years ago to denote lakes that do not annually mix completely. Since then our understanding of meromictic lakes has considerably advanced. Physical processes support the difference in water density between deep (monimolimnion ) and surface (mixolimnion ) waters in meromictic lakes; such lakes reveal complex biogeochemical interactions that contribute to the maintenance of meromixis. This Conclusion chapter of the book on Ecology of Meromictic Lakes presents the general overview of physical, chemical and biological properties of meromictic lakes, based partly on the foregoing 12 chapters. The broad spectrum of meromixis supported by different processes in lakes located in different regions and climates is presented. We stress the importance of undisturbed sediments in meromictic lakes as paleolimnological archives and demonstrate how this information can be used to reconstruct lake history and development over longer time periods. The ef...
Case studies and typical examples for meromictic lakes are used to provide a review of the biolog... more Case studies and typical examples for meromictic lakes are used to provide a review of the biology and ecology of these ecosystems. Water column in meromictic lakes is not entirely mixed. These lakes are chemically and/or thermally stratified for several years and have several specific ecological features. The chemocline —the habitat created between the mixolimnion on top and monimolimnion below—is characterised by the existence of complex bacterial communities, autotrophic and heterotrophic protists and metazooplankton, commonly dominated by rotifers , high rates of oxygenic and anoxygenic photosynthesis and some biogeochemical processes . In these lakes, the sulphur, carbon and nitrogen cycles are partially coupled. However, a large number of bacterial and archaeal taxa, especially in anoxic waters, are still unidentified. An unaccomplished important task is to both investigate the uncultivated microbial diversity and access metabolic potential of the bacterial communities in mero...
The aim of the study is to compare concentrations of cadmium and nickel that induce negative effe... more The aim of the study is to compare concentrations of cadmium and nickel that induce negative effects on survival and life cycle parameters of active and resting stages of cladoceran Moina macrocopa. In acute and chronic tests with active animals we determined standard toxicological parameters: half lethal concentration (LC50) when 50 % mortality of tested animals is observed and effective concentration (EC50) when 50 % reduction of the net reproductive rate of females of Moina macrocopa is detected. LC50 for cadmium in 48-hours test was equal to 0.18 mg/l; for nickel-5.59 mg/l. EC50 for cadmium was equal to 0.005 mg/l, for nickel-0.323 mg/l. It was demonstrated that long-term (30-40 days) exposure of resting eggs of M. macrocopa to the effect of solutes of cadmium and nickel in the wide range of concentrations (from background to the 60-70 g/l) did not affect the survival of resting eggs and life cycle parameters (specific rate of juvenile growth, number of hatched clutches, net reproductive rate) of hatchlings from exposed eggs. Thus, resting eggs of M. macrocopa can tolerate without negative survival effects concentrations of toxicants that far exceed the concentrations that are toxic for active animals, which confirm high resistance of resting eggs to the effect of heavy metals.
We start with the recent developments and reasons why the meromictic lakes should get more attent... more We start with the recent developments and reasons why the meromictic lakes should get more attention in limnological literature. Thereafter, we define monimolimnion , mixolimnion and some other terms related to meromixis. The definition of Hutchinson for meromictic lakes holds for more than 60 years while some modification is required. We differentiate between a meromictic lake and a non-meromictic ones, despite the fact that for deep waters the patterns of recirculation in non-meromictic lakes may be similar to meromixis. We also refer briefly to the classification schemes of meromixis and list processes involved in sustaining stratification. Regions on the Globe that produce salinity gradients in surface waters; mining areas, where geochemistry is more actively operative; and areas where waters of different compositions meet may promote the development of such conditions in lakes. Meromixis is a much more dynamic process than it is often understood. If monimolimnion gets eroded, the meromixis can terminate, while changes in the hydrology can turn a lake meromictic. Finally, we briefly introduce here the structure of this book, which has three parts. Part I focuses on physical (Chap. 2), chemical (Chap. 3) and biological (Chap. 4) properties of meromictic lakes. Part II presents eight case studies in separate chapters including the regional studies on different meromictic lakes in five continents. Part III (Chap. 13) is based mainly on the brief conclusion summaries derived from the preceding 12 chapters with editors’ remarks. Lastly, this book is an attempt to update our available knowhow and expertise on the existing state-of-the-art information on meromictic lakes and the literature references that can form the basis for future studies on meromictic lakes.
Journal of Siberian Federal University. Biology, 2017
The aim of the study is to compare concentrations of cadmium and nickel that induce negative effe... more The aim of the study is to compare concentrations of cadmium and nickel that induce negative effects on survival and life cycle parameters of active and resting stages of cladoceran Moina macrocopa. In acute and chronic tests with active animals we determined standard toxicological parameters: half lethal concentration (LC50) when 50 % mortality of tested animals is observed and effective concentration (EC50) when 50 % reduction of the net reproductive rate of females of Moina macrocopa is detected. LC50 for cadmium in 48-hours test was equal to 0.18 mg/l; for nickel-5.59 mg/l. EC50 for cadmium was equal to 0.005 mg/l, for nickel-0.323 mg/l. It was demonstrated that long-term (30-40 days) exposure of resting eggs of M. macrocopa to the effect of solutes of cadmium and nickel in the wide range of concentrations (from background to the 60-70 g/l) did not affect the survival of resting eggs and life cycle parameters (specific rate of juvenile growth, number of hatched clutches, net reproductive rate) of hatchlings from exposed eggs. Thus, resting eggs of M. macrocopa can tolerate without negative survival effects concentrations of toxicants that far exceed the concentrations that are toxic for active animals, which confirm high resistance of resting eggs to the effect of heavy metals.
We investigated the sensitivity of resting eggs of the cladoceran Moina macrocopa to the effect o... more We investigated the sensitivity of resting eggs of the cladoceran Moina macrocopa to the effect of ionizing radiation during the reactivation of the eggs. The study showed that the resting eggs during reactivation are more vulnerable to irradiation than the resting eggs in a stage of deep dormancy. The decrease in the efficiency of egg reactivation was observed at high doses, the growth rate of juveniles, fecundity, and the number of produced clutches by females strongly decreased when resting eggs at the reactivation stage absorbed doses of 64 Gy and higher.
This review is part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosyste... more This review is part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report on Europe and Central Asia (ECA) and provides a critical assessment of issues facing decision-makers, including freshwater biodiversity and ecosystem trends as well as drivers of change. Freshwater systems are well established as the most threatened ecosystem type in the ECA region, with the quantity and quality of habitats and abundance of many species rapidly declining. Only about half (53%) of the EU's rivers and lakes achieved good ecological status in 2015 (as defined by the Water Framework Directive in terms of the quality of the biological community), and many lakes, ponds, and streams are disappearing as a consequence of agricultural intensification and ineffective irrigation and urbanisation, combined with climate change. The situation regarding freshwater biodiversity remains highly critical in ECA as many species remain threatened with extinction, including >50% of known species for some groups (e.g., molluscs, amphibians). Drivers of ECA freshwater taxa include the destruction or modification of their habitat, including water abstraction, which affects ∼89% of all amphibian threatened species and ∼26% of threatened freshwater invertebrate species. Of particular concern is the lack of data for freshwater invertebrates. Current status is available for only a minority of species, and the impact of alien invasive species is often unknown, especially in Central Asia. Based on current freshwater biodiversity trends, it is highly unlikely that ECA will achieve either the respective Aichi biodiversity targets by 2020 (i.e., targets, 2-4,6-12,14) or Target 1 of the Biodiversity Strategy.
We used a Lake Shira numerical model to estimate the response of the ecosystem of a saline meromi... more We used a Lake Shira numerical model to estimate the response of the ecosystem of a saline meromictic lake to variations in weather parameters during the growing season. The sensitivity analysis of the model suggests that compared to other external (nutrient infl ows) and internal (spring biomasses of food-web components) factors, weather parameters are among the most infl uential for both mixolimnetic (phyto-and zooplankton) and monimolimnetic (purple sulfur bacteria, sulfur reducing bacteria and hydrogen sulfi de) food-web components. Calculations with diff erent weather scenarios shows how changes in the water temperature and mixing depth aff ect mixolimnetic and monimolimnetic food-web components and the depth of the oxic-anoxic interface in a meromictic lake. When weather forcing stimulates an increase in the biomass of food-web components in the mixolimnion, it produces cascading eff ects that lead to three results: 1) a higher content of detritus in the water column; 2) a higher content of hydrogen sulfi de in the monimolimnion; 3) raising of the oxic-anoxic interface closer to the water-air surface. This cascading eff ect is complicated by the negative correlation between two light dependent primary producers located at diff erent depths-phytoplankton in the mixolimnion and purple sulfur bacteria at the oxic-anoxic interface. Thus, weather conditions that stimulate higher phytoplankton biomass are associated with a higher detritus content and lower biomass of purple sulfur bacteria, a higher content of hydrogen sulfi de and a shallower oxic-anoxic interface. The same weather conditions (higher wind, lower cloud cover, and lower air temperature) promote a scenario of less stable thermal stratifi cation. Thus, our calculations suggest that weather parameters during the summer season strongly control the mixing depth, water temperature and the mixolimnetic food web. An eff ect of biogeochemical and physical interactions on the depth of the oxicanoxic interface is also detectable. However, intra-and interannual climate and weather eff ects will be more important for the control of meromixis stability.
Climate change and other anthropogenic stressors have led to long-term changes in the thermal str... more Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of...
Saline lakes are widespread on all continents. Since 1979, an informal international association ... more Saline lakes are widespread on all continents. Since 1979, an informal international association of salt lake researchers from a variety of disciplines has sponsored a series of triennial conferences to foster scientific exchange and our understanding of saline lakes. International Society for Salt Lake Research (ISSLR, www.isslr.org) was founded in 1994 to establish effective liaison between persons interested in any aspect of inland saline waters, to encourage these interests, and to educate the public in the scientific use, management, and conservation of salt lakes. ISSLR conferences are held triennially. The conferences are usually hosted by a local University or research institution and provide an excellent opportunity for networking among globally dispersed researchers.
Temperature and precipitation patterns are changing considerably worldwide because of global clim... more Temperature and precipitation patterns are changing considerably worldwide because of global climate change [...]
Many continental saline lakes are under the effects of salinity increase and anthropogenic eutrop... more Many continental saline lakes are under the effects of salinity increase and anthropogenic eutrophication exacerbated by global change. The response of the food web to these drivers of change is not straightforward. To understand the consequences of salinity and eutrophication interactive effects on the food web, we studied the seasonal dynamics of zooplankton and phytoplankton and water quality parameters in 20 lakes of different salinity (from freshwater to hypersaline) and nutrient status (from oligotrophic to eutrophic) located in southern Siberia. We observed a pronounced bottom-up effect of nutrients, which induced an increase in the biomass of phytoplankton and zooplankton and a decline in water quality. A significant decrease in the species abundance of zooplankton was observed at a threshold salinity of 3 g L−1 and the disappearance of fish at 10 g L−1. The top-down effect induced by salinity manifested itself in an increase in the biomass of zooplankton with the disappeara...
We investigated the effects of γ-radiation on the survival of resting eggs of the cladoceran Moin... more We investigated the effects of γ-radiation on the survival of resting eggs of the cladoceran Moina macrocopa, on the parameters of the life cycle of neonates hatched from the irradiated eggs and on the performance of the population initiated from irradiated eggs. The study showed that γ-radiation in a range of doses from the background level to 100 Gy had no effect on survival of irradiated eggs. The absorbed dose of 200 Gy was lethal to resting eggs of M. macrocopa. The number of clutches and net reproductive rate (R0) of hatchlings from eggs exposed to radiation were the strongly affected parameters. The number of clutches was drastically reduced for females hatched from egg exposed to 80-100 Gy. The most sensitive parameter was the R0. The estimated ED50 for the R0 (effective dose that induces 50% R0 reduction) was 50 Gy. Population performance was also affected by the irradiation of the resting stage of animals that initiated population. Populations that was initiated from hatchlings from resting eggs exposed to 100 Gy was of smaller size and with fewer juvenile and parthenogenetic females in comparison with control populations. Thus, we determined the dose-response relationship for the effect of gamma radiation on survival of resting eggs and individual and population responses of hatchlings from irradiated resting eggs. We conclude that for highly polluted areas contamination of bottom sediments with radioactive materials could affect zooplankton communities through adverse chronic effects on resting eggs, which will be transmitted to hatchlings at individual or population levels.
This volume presents recent advances in the research on meromictic lakes and a state-of-the art o... more This volume presents recent advances in the research on meromictic lakes and a state-of-the art overview of this area. After an introduction to the terminology and geographic distribution of meromictic lakes, three concise chapters describe their physical, chemical and biological features. The following eight chapters present case studies of more than a dozen meromictic lakes, showing the variety of physical and biochemical processes that promote meromixis. The result is a broad picture of the ecology and biochemistry of meromictic lakes in tropical and cold regions, in man-made pit lakes and euxinic marine lakes, and in freshwater as well as hypersaline lakes. In the final chapter the editors provide a synthesis of the topic and conclude that the study of meromictic lakes also offers new insights into the limnology of inland lakes. The book appeals to researchers in the fields of ecology, limnology, environmental physics and biophysics.
The long-term data (1996–2021) on the summer abundances of the dominant zooplankton species (cope... more The long-term data (1996–2021) on the summer abundances of the dominant zooplankton species (copepod Arctodiaptomus salinus (Daday, 1885), rotifers Brachionus plicatilis (Müller, 1786) and Hexarthra sp.) in saline Lake Shira were used to analyze the response of zooplankton to air temperature and a change in the circulation regime of the lake: breakdown and reestablishment of meromixis. All groups of zooplankton responded to prolonged summer elevated temperatures by increasing their abundance. During the breakdown of the stable stratification of Lake Shira (2015–2016), zooplankton abundance increased on average by a factor of two and amounted to 9×105 inds./m2 in the water column for copepods. That increase coincided with similar responses of other components of the lake’s mixolimnion ecosystem, whose biomasses increased approximately two-fold during that period. After the reestablishment of the meromixis, the abundance of zooplankton decreased to previous values. Thus, the abundance of zooplankton is largely determined by weather (the effect of temperature) and ecological factors (mixing regime).
The cladoceran Daphnia magna inhabits lakes with salinities up to 10 g L −1 . We compared the eff... more The cladoceran Daphnia magna inhabits lakes with salinities up to 10 g L −1 . We compared the effects of different salinities (up to 9 g L −1 ) on the survival, specific grazing rate, and size selective feeding of Daphnia females adapted to fresh or saline waters (3–4 g L −1 ). The freshwater population was more sensitive to high salinity (LC 50 = 5.3 g L −1 ), while the survival of the saline water population also decreased in fresh water. Freshwater population demonstrated a higher grazing rate in fresh water, while the saline water population had a higher grazing rate at the salinity above 3 g L −1 . A decrease in the grazing rate of the freshwater population was observed at the salinity above 4–5 g L −1 . Populations differed in food selectivity. The saline water population consumed particles of larger sizes than the freshwater population. The average size of phytoplankton particles grazed in fresh water was larger than in saline water. This size selective salinity-dependent grazing may be related to the dependence of the feeding efficiency of cladocerans on the viscosity of water and size of phytoplankton particles. Our results indicate that Daphnia populations adapted to a certain salinity can temporarily lose the ability to control phytoplankton because of salinity fluctuations.
Journal of Siberian Federal University. Biology, 2021
Salinity largely determines the species diversity and structure of the food web in lake ecosystem... more Salinity largely determines the species diversity and structure of the food web in lake ecosystems. Many studies have been focused on the salinity tolerance of various plankton species. There are fewer studies investigating the modifications in the food web interactions under the effect of salinity. An appropriate system for such studies is closely located lakes of different salinity. We took samples during the summer stratification and analyzed the physicochemical and biological characteristics of 20 lakes (salinity 0.1-35 g/l) in southern Siberia in order to provide general description of this system and to test a number of hypotheses about the effect of salinity on the structure of the food web. The analysis revealed two key factors structuring ecosystems of the studied lakes. The species composition of zooplankton was determined by salinity, with a decrease in the number of species and the transformation of the community from a diverse community of zooplankton (salinity up to 3 ...
The term meromixis was introduced more than 80 years ago to denote lakes that do not annually mix... more The term meromixis was introduced more than 80 years ago to denote lakes that do not annually mix completely. Since then our understanding of meromictic lakes has considerably advanced. Physical processes support the difference in water density between deep (monimolimnion ) and surface (mixolimnion ) waters in meromictic lakes; such lakes reveal complex biogeochemical interactions that contribute to the maintenance of meromixis. This Conclusion chapter of the book on Ecology of Meromictic Lakes presents the general overview of physical, chemical and biological properties of meromictic lakes, based partly on the foregoing 12 chapters. The broad spectrum of meromixis supported by different processes in lakes located in different regions and climates is presented. We stress the importance of undisturbed sediments in meromictic lakes as paleolimnological archives and demonstrate how this information can be used to reconstruct lake history and development over longer time periods. The ef...
Case studies and typical examples for meromictic lakes are used to provide a review of the biolog... more Case studies and typical examples for meromictic lakes are used to provide a review of the biology and ecology of these ecosystems. Water column in meromictic lakes is not entirely mixed. These lakes are chemically and/or thermally stratified for several years and have several specific ecological features. The chemocline —the habitat created between the mixolimnion on top and monimolimnion below—is characterised by the existence of complex bacterial communities, autotrophic and heterotrophic protists and metazooplankton, commonly dominated by rotifers , high rates of oxygenic and anoxygenic photosynthesis and some biogeochemical processes . In these lakes, the sulphur, carbon and nitrogen cycles are partially coupled. However, a large number of bacterial and archaeal taxa, especially in anoxic waters, are still unidentified. An unaccomplished important task is to both investigate the uncultivated microbial diversity and access metabolic potential of the bacterial communities in mero...
The aim of the study is to compare concentrations of cadmium and nickel that induce negative effe... more The aim of the study is to compare concentrations of cadmium and nickel that induce negative effects on survival and life cycle parameters of active and resting stages of cladoceran Moina macrocopa. In acute and chronic tests with active animals we determined standard toxicological parameters: half lethal concentration (LC50) when 50 % mortality of tested animals is observed and effective concentration (EC50) when 50 % reduction of the net reproductive rate of females of Moina macrocopa is detected. LC50 for cadmium in 48-hours test was equal to 0.18 mg/l; for nickel-5.59 mg/l. EC50 for cadmium was equal to 0.005 mg/l, for nickel-0.323 mg/l. It was demonstrated that long-term (30-40 days) exposure of resting eggs of M. macrocopa to the effect of solutes of cadmium and nickel in the wide range of concentrations (from background to the 60-70 g/l) did not affect the survival of resting eggs and life cycle parameters (specific rate of juvenile growth, number of hatched clutches, net reproductive rate) of hatchlings from exposed eggs. Thus, resting eggs of M. macrocopa can tolerate without negative survival effects concentrations of toxicants that far exceed the concentrations that are toxic for active animals, which confirm high resistance of resting eggs to the effect of heavy metals.
We start with the recent developments and reasons why the meromictic lakes should get more attent... more We start with the recent developments and reasons why the meromictic lakes should get more attention in limnological literature. Thereafter, we define monimolimnion , mixolimnion and some other terms related to meromixis. The definition of Hutchinson for meromictic lakes holds for more than 60 years while some modification is required. We differentiate between a meromictic lake and a non-meromictic ones, despite the fact that for deep waters the patterns of recirculation in non-meromictic lakes may be similar to meromixis. We also refer briefly to the classification schemes of meromixis and list processes involved in sustaining stratification. Regions on the Globe that produce salinity gradients in surface waters; mining areas, where geochemistry is more actively operative; and areas where waters of different compositions meet may promote the development of such conditions in lakes. Meromixis is a much more dynamic process than it is often understood. If monimolimnion gets eroded, the meromixis can terminate, while changes in the hydrology can turn a lake meromictic. Finally, we briefly introduce here the structure of this book, which has three parts. Part I focuses on physical (Chap. 2), chemical (Chap. 3) and biological (Chap. 4) properties of meromictic lakes. Part II presents eight case studies in separate chapters including the regional studies on different meromictic lakes in five continents. Part III (Chap. 13) is based mainly on the brief conclusion summaries derived from the preceding 12 chapters with editors’ remarks. Lastly, this book is an attempt to update our available knowhow and expertise on the existing state-of-the-art information on meromictic lakes and the literature references that can form the basis for future studies on meromictic lakes.
Journal of Siberian Federal University. Biology, 2017
The aim of the study is to compare concentrations of cadmium and nickel that induce negative effe... more The aim of the study is to compare concentrations of cadmium and nickel that induce negative effects on survival and life cycle parameters of active and resting stages of cladoceran Moina macrocopa. In acute and chronic tests with active animals we determined standard toxicological parameters: half lethal concentration (LC50) when 50 % mortality of tested animals is observed and effective concentration (EC50) when 50 % reduction of the net reproductive rate of females of Moina macrocopa is detected. LC50 for cadmium in 48-hours test was equal to 0.18 mg/l; for nickel-5.59 mg/l. EC50 for cadmium was equal to 0.005 mg/l, for nickel-0.323 mg/l. It was demonstrated that long-term (30-40 days) exposure of resting eggs of M. macrocopa to the effect of solutes of cadmium and nickel in the wide range of concentrations (from background to the 60-70 g/l) did not affect the survival of resting eggs and life cycle parameters (specific rate of juvenile growth, number of hatched clutches, net reproductive rate) of hatchlings from exposed eggs. Thus, resting eggs of M. macrocopa can tolerate without negative survival effects concentrations of toxicants that far exceed the concentrations that are toxic for active animals, which confirm high resistance of resting eggs to the effect of heavy metals.
We investigated the sensitivity of resting eggs of the cladoceran Moina macrocopa to the effect o... more We investigated the sensitivity of resting eggs of the cladoceran Moina macrocopa to the effect of ionizing radiation during the reactivation of the eggs. The study showed that the resting eggs during reactivation are more vulnerable to irradiation than the resting eggs in a stage of deep dormancy. The decrease in the efficiency of egg reactivation was observed at high doses, the growth rate of juveniles, fecundity, and the number of produced clutches by females strongly decreased when resting eggs at the reactivation stage absorbed doses of 64 Gy and higher.
This review is part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosyste... more This review is part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report on Europe and Central Asia (ECA) and provides a critical assessment of issues facing decision-makers, including freshwater biodiversity and ecosystem trends as well as drivers of change. Freshwater systems are well established as the most threatened ecosystem type in the ECA region, with the quantity and quality of habitats and abundance of many species rapidly declining. Only about half (53%) of the EU's rivers and lakes achieved good ecological status in 2015 (as defined by the Water Framework Directive in terms of the quality of the biological community), and many lakes, ponds, and streams are disappearing as a consequence of agricultural intensification and ineffective irrigation and urbanisation, combined with climate change. The situation regarding freshwater biodiversity remains highly critical in ECA as many species remain threatened with extinction, including >50% of known species for some groups (e.g., molluscs, amphibians). Drivers of ECA freshwater taxa include the destruction or modification of their habitat, including water abstraction, which affects ∼89% of all amphibian threatened species and ∼26% of threatened freshwater invertebrate species. Of particular concern is the lack of data for freshwater invertebrates. Current status is available for only a minority of species, and the impact of alien invasive species is often unknown, especially in Central Asia. Based on current freshwater biodiversity trends, it is highly unlikely that ECA will achieve either the respective Aichi biodiversity targets by 2020 (i.e., targets, 2-4,6-12,14) or Target 1 of the Biodiversity Strategy.
We used a Lake Shira numerical model to estimate the response of the ecosystem of a saline meromi... more We used a Lake Shira numerical model to estimate the response of the ecosystem of a saline meromictic lake to variations in weather parameters during the growing season. The sensitivity analysis of the model suggests that compared to other external (nutrient infl ows) and internal (spring biomasses of food-web components) factors, weather parameters are among the most infl uential for both mixolimnetic (phyto-and zooplankton) and monimolimnetic (purple sulfur bacteria, sulfur reducing bacteria and hydrogen sulfi de) food-web components. Calculations with diff erent weather scenarios shows how changes in the water temperature and mixing depth aff ect mixolimnetic and monimolimnetic food-web components and the depth of the oxic-anoxic interface in a meromictic lake. When weather forcing stimulates an increase in the biomass of food-web components in the mixolimnion, it produces cascading eff ects that lead to three results: 1) a higher content of detritus in the water column; 2) a higher content of hydrogen sulfi de in the monimolimnion; 3) raising of the oxic-anoxic interface closer to the water-air surface. This cascading eff ect is complicated by the negative correlation between two light dependent primary producers located at diff erent depths-phytoplankton in the mixolimnion and purple sulfur bacteria at the oxic-anoxic interface. Thus, weather conditions that stimulate higher phytoplankton biomass are associated with a higher detritus content and lower biomass of purple sulfur bacteria, a higher content of hydrogen sulfi de and a shallower oxic-anoxic interface. The same weather conditions (higher wind, lower cloud cover, and lower air temperature) promote a scenario of less stable thermal stratifi cation. Thus, our calculations suggest that weather parameters during the summer season strongly control the mixing depth, water temperature and the mixolimnetic food web. An eff ect of biogeochemical and physical interactions on the depth of the oxicanoxic interface is also detectable. However, intra-and interannual climate and weather eff ects will be more important for the control of meromixis stability.
Climate change and other anthropogenic stressors have led to long-term changes in the thermal str... more Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of...
Saline lakes are widespread on all continents. Since 1979, an informal international association ... more Saline lakes are widespread on all continents. Since 1979, an informal international association of salt lake researchers from a variety of disciplines has sponsored a series of triennial conferences to foster scientific exchange and our understanding of saline lakes. International Society for Salt Lake Research (ISSLR, www.isslr.org) was founded in 1994 to establish effective liaison between persons interested in any aspect of inland saline waters, to encourage these interests, and to educate the public in the scientific use, management, and conservation of salt lakes. ISSLR conferences are held triennially. The conferences are usually hosted by a local University or research institution and provide an excellent opportunity for networking among globally dispersed researchers.
Temperature and precipitation patterns are changing considerably worldwide because of global clim... more Temperature and precipitation patterns are changing considerably worldwide because of global climate change [...]
Many continental saline lakes are under the effects of salinity increase and anthropogenic eutrop... more Many continental saline lakes are under the effects of salinity increase and anthropogenic eutrophication exacerbated by global change. The response of the food web to these drivers of change is not straightforward. To understand the consequences of salinity and eutrophication interactive effects on the food web, we studied the seasonal dynamics of zooplankton and phytoplankton and water quality parameters in 20 lakes of different salinity (from freshwater to hypersaline) and nutrient status (from oligotrophic to eutrophic) located in southern Siberia. We observed a pronounced bottom-up effect of nutrients, which induced an increase in the biomass of phytoplankton and zooplankton and a decline in water quality. A significant decrease in the species abundance of zooplankton was observed at a threshold salinity of 3 g L−1 and the disappearance of fish at 10 g L−1. The top-down effect induced by salinity manifested itself in an increase in the biomass of zooplankton with the disappeara...
We investigated the effects of γ-radiation on the survival of resting eggs of the cladoceran Moin... more We investigated the effects of γ-radiation on the survival of resting eggs of the cladoceran Moina macrocopa, on the parameters of the life cycle of neonates hatched from the irradiated eggs and on the performance of the population initiated from irradiated eggs. The study showed that γ-radiation in a range of doses from the background level to 100 Gy had no effect on survival of irradiated eggs. The absorbed dose of 200 Gy was lethal to resting eggs of M. macrocopa. The number of clutches and net reproductive rate (R0) of hatchlings from eggs exposed to radiation were the strongly affected parameters. The number of clutches was drastically reduced for females hatched from egg exposed to 80-100 Gy. The most sensitive parameter was the R0. The estimated ED50 for the R0 (effective dose that induces 50% R0 reduction) was 50 Gy. Population performance was also affected by the irradiation of the resting stage of animals that initiated population. Populations that was initiated from hatchlings from resting eggs exposed to 100 Gy was of smaller size and with fewer juvenile and parthenogenetic females in comparison with control populations. Thus, we determined the dose-response relationship for the effect of gamma radiation on survival of resting eggs and individual and population responses of hatchlings from irradiated resting eggs. We conclude that for highly polluted areas contamination of bottom sediments with radioactive materials could affect zooplankton communities through adverse chronic effects on resting eggs, which will be transmitted to hatchlings at individual or population levels.
This volume presents recent advances in the research on meromictic lakes and a state-of-the art o... more This volume presents recent advances in the research on meromictic lakes and a state-of-the art overview of this area. After an introduction to the terminology and geographic distribution of meromictic lakes, three concise chapters describe their physical, chemical and biological features. The following eight chapters present case studies of more than a dozen meromictic lakes, showing the variety of physical and biochemical processes that promote meromixis. The result is a broad picture of the ecology and biochemistry of meromictic lakes in tropical and cold regions, in man-made pit lakes and euxinic marine lakes, and in freshwater as well as hypersaline lakes. In the final chapter the editors provide a synthesis of the topic and conclude that the study of meromictic lakes also offers new insights into the limnology of inland lakes. The book appeals to researchers in the fields of ecology, limnology, environmental physics and biophysics.
This volume presents recent advances in the research on meromictic lakes and a state-of-the art o... more This volume presents recent advances in the research on meromictic lakes and a state-of-the art overview of this area. After an introduction to the terminology and geographic distribution of meromictic lakes, three concise chapters describe their physical, chemical and biological features. The following eight chapters present case studies of more than a dozen meromictic lakes, showing the variety of physical and biochemical processes that promote meromixis. The result is a broad picture of the ecology and biochemistry of meromictic lakes in tropical and cold regions, in man-made pit lakes and euxinic marine lakes, and in freshwater as well as hypersaline lakes. In the final chapter the editors provide a synthesis of the topic and conclude that the study of meromictic lakes also offers new insights into the limnology of inland lakes. The book appeals to researchers in the fields of ecology, limnology, environmental physics and biophysics.
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Papers by Egor Zadereev