Article

Responses of trophic structure and zooplankton community to salinity and temperature in Tibetan lakes: Implication for the effect of climate warming

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Abstract

Warming has pronounced effects on lake ecosystems, either directly by increased temperatures or indirectly by a change in salinity. We investigated the current status of zooplankton communities and trophic structure in 45 Tibetan lakes along a 2300 m altitude and a 76 g/l salinity gradient. Freshwater to hyposaline lakes mainly had three trophic levels: phytoplankton, small zooplankton and fish/Gammarus, while mesosaline to hypersaline lakes only had two: phytoplankton and large zooplankton. Zooplankton species richness declined significantly with salinity, but did not relate with temperature. Furthermore, the decline in species richness with salinity in lakes with two trophic levels was much less abrupt than in lakes with three trophic levels. The structural variation of the zooplankton community depended on the length of the food chain, and was significantly explained by salinity as the critical environmental variable. The zooplankton community shifted from dominance of copepods and small cladoceran species in the lakes with low salinity and three trophic levels to large saline filter-feeding phyllopod species in those lakes with high salinity and two trophic levels. The zooplankton to phytoplankton biomass ratio was positively related with temperature in two-trophic-level systems and vice versa in three-trophic-level systems. As the Tibetan Plateau is warming about three times faster than the global average, our results imply that warming could have a considerable impact on the structure and function of Tibetan lake ecosystems, either via indirect effects of salinization/desalinization on species richness, composition and trophic structure or through direct effects of water temperature on trophic interactions.

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... As a result of this increased meltwater, numerous lakes have expanded (Zhang et al., 2015) and lake levels have increased (Zhang et al., 2011). These thermal and hydrologic changes could have severe impacts on the structure and function of lake ecosystems (Lin et al., 2017). For instance, enhanced inputs of glacial meltwater can alter lake hydrology, salinity, enhanced stratification and nutrient regime, and thereby impede internal nutrient loading to limit algal blooms (Posch et al., 2012;Slemmons and Saros, 2012) and biodiversity (Milner et al., 2009). ...
... The trophic structure of most Tibetan lakes is relatively simple, with Daphnia tibetana and/or Artemia tibetiana forming the top trophic level in lakes without fish (Lin et al., 2017). Daphnia (Cladoceran) are known to be of pivotal ecological importance in lakes and ponds because they are large filter-feeding zooplankton that consume copious amounts and varieties of algae (Carpenter and Kitchell, 1996). ...
... The brine shrimp Artemia (Anostraca) has a broad geographical distribution inhabiting both inland and coastal saline and hypersaline lakes (Abatzopoulos et al., 1998). Salinity is an important driver of the distribution of these zooplankton in QTP, as Artemia tibetiana can survive salinities between 25 and 75 g/L, whereas Daphnia tibetana mainly survive between 5 and 28 g/L (Lin et al., 2017). Since the late 1970s, global commercial breeding of fish has led to increased human consumption of Artemia (Sorgeloos et al., 2001). ...
Article
Modelling, monitoring, and experimental data have shown that global climate change can impact aquatic phytoplankton communities directly, through the effects of warming on primary producers, as well as indirectly through cascading effects from higher trophic levels. Although both concepts are common in modern limnological studies, it remains unclear whether the ‘top-down’ effects from higher trophic levels on phytoplankton exert strong effects in natural systems over long (centennial) timescales. Here, we use multiproxy data including pigments, zooplankton remains, nutrient concentrations, and paleoclimate indicators from a sediment core in Dagze Co, Central Tibet (a two-trophic level lake) to reconstruct algal production, zooplankton community, nutrient and salinity changes. Our results show that top-down effects of higher trophic levels offset effects from warming and nutrient addition on algal growth. Warming enhanced glacial meltwater inflow to the lake, and intensive human activities increased nutrient inputs. Changes in lake salinity and N:P ratios coincided with zooplankton community shifts during the past 600 years, and Daphnia tibetana replaced the brine shrimp, Artemia tibetiana, after the relocation of a town to upstream of the lake in the 1980s led to overharvesting of the brine shrimp. These shifts contributed strongly to changes in algal communities, with changes in zooplankton leading to strong top-down effects that decreased algal production through increasing grazing pressure despite increasing nutrient concentrations. Our results suggest that the typical external drivers (climate and nutrients) of lake ecosystems may be suppressed by internal shifts in plankton communities in lakes.
... The magnitude of the future changes poses a major threat to the functioning and biodiversity of inland aquatic ecosystems. Many lakes may dry out temporarily or permanently with rising temperature, while salinisation in the remaining waterbodies may lead to reduced biodiversity (Williams et al. 1990, Schallenberg et al. 2003, Flöder and Burns 2004, Jeppesen et al. 2015 and loss of ecosystem functioning (Lin et al. 2017, Vidal et al. 2021. To date, however, knowledge of the effects of warming on saline lakes is fragmented and far from the level achieved for freshwater lakes (Jeppesen et al. 2015, Cañedo-Argüells et al. 2019. ...
... Increasing salinity may lead to reduced biodiversity and an expected loss of ecosystem functioning (Williams et al. 1990, Schallenberg et al. 2003, Flöder and Burns 2004, Kipriyanova et al. 2007, Jeppesen et al. 2015, Anufriieva and Shadrin 2018, Golubkov et al. 2018. Often, pronounced effects are seen when specific salinity thresholds are surpassed, such as a complete loss of fish at high salinities (Lin et al. 2017, Vidal et al. 2021). In addition, widespread drainage of the wetlands and deterioration of the lake ecosystems in the KCB in the last 60 years have resulted in major declines in the populations of threatened waterbirds and species richness in the region ( Fig. 9 and 10). ...
... Such changes are also accompanied by salinisation, a state where even a few years with a prolonged hydraulic residence time can shift a lake to briny conditions . Apart from eutrophication, the expected salinity changes will severely affect the biodiversity and trophic dynamics of the KCB lakes (Brucet et al. 2012, Lin et al. 2017, Zadereev et al. 2020, Vidal et al. 2021, and major shifts may occur when certain salinity thresholds are surpassed (Jeppesen et al. 2007, Lin et al. 2017. To reverse the ecosystem degradation or even preserve the current status, a framework policy is needed that aims to restrict the exploitation of water resources within sustainable limits in the KCB while simultaneously promoting conservation efforts. ...
Article
The Konya Closed Basin (KCB) in Turkey has a cold semiarid to warm Mediterranean climate and hosts the largest Turkish freshwater lake, Lake Beyşehir, and the iconic saline Lake Tuz. Using published as well as our own ground-truth and remote sensing data, we provide (1) a brief description of the paleoenvironmental changes in the KCB; followed by (2) a detailed description of the changes in land use, crop farming, groundwater and surface water levels, and climate; and (3) associated changes in lake water surface area and salinity as well as in waterbird and fish communities during the past 40 years. The KCB is intensively farmed, and the farming of mainly water intensive crops has increased substantially, especially since 2000. This, combined with climate warming, has led to a substantial rate of reduction of the groundwater level (up to 1 m/yr) and the surface area of the lakes and wetlands, followed by an increase in salinisation, and even complete loss of several wetlands. Three globally threatened waterbird species face extinction in the basin, and 18 of the 62 previous breeding species have already been lost. The KCB has 38 fish species, of which 74% are endemic and 61% are considered threatened or near threatened. Modelling projections using various climate and land use scenarios predict serious additional reductions of the water level in the future due to climate change, leading to deterioration (or complete loss) of lake ecosystems and the services they provide.
... As a result of this increased meltwater, numerous lakes have expanded (Zhang et al., 2015) and lake levels have increased (Zhang et al., 2011). These thermal and hydrologic changes could have severe impacts on the structure and function of lake ecosystems (Lin et al., 2017). For instance, enhanced inputs of glacial meltwater can alter lake hydrology, salinity, enhanced stratification and nutrient regime, and thereby impede internal nutrient loading to limit algal blooms (Posch et al., 2012;Slemmons and Saros, 2012) and biodiversity (Milner et al., 2009). ...
... The trophic structure of most Tibetan lakes is relatively simple, with Daphnia tibetana and/or Artemia tibetiana forming the top trophic level in lakes without fish (Lin et al., 2017). Daphnia (Cladoceran) are known to be of pivotal ecological importance in lakes and ponds because they are large filter-feeding zooplankton that consume copious amounts and varieties of algae (Carpenter and Kitchell, 1996). ...
... The brine shrimp Artemia (Anostraca) has a broad geographical distribution inhabiting both inland and coastal saline and hypersaline lakes (Abatzopoulos et al., 1998). Salinity is an important driver of the distribution of these zooplankton in QTP, as Artemia tibetiana can survive salinities between 25 and 75 g/L, whereas Daphnia tibetana mainly survive between 5 and 28 g/L (Lin et al., 2017). Since the late 1970s, global commercial breeding of fish has led to increased human consumption of Artemia (Sorgeloos et al., 2001). ...
Article
Modelling, monitoring, and experimental data have shown that global climate change can impact aquatic phytoplankton communities directly, through the effects of warming on primary producers, as well as indirectly through cascading effects from higher trophic levels. Although both concepts are common in modern limnological studies, it remains unclear whether the ‘top-down’ effects from higher trophic levels on phytoplankton exert strong effects in natural systems over long (centennial) timescales. Here, we use multiproxy data including pigments, zooplankton remains, nutrient concentrations, and paleoclimate indicators from a sediment core in Dagze Co, Central Tibet (a two-trophic level lake) to reconstruct algal production, zooplankton community, nutrient salinity changes. Our results show that top-down effects of higher trophic levels offset effects from warming and nutrient addition on algal growth. Warming enhanced glacial meltwater inflow to the lake, and intensive human activities increased nutrient inputs. Changes in lake salinity and N:P ratios coincided with zooplankton community shifts during the past 600 years, and Daphnia tibetana replaced the brine shrimp, Artemia tibetiana, after the relocation of a town to upstream of the lake in the 1980s led to overharvesting of the brine shrimp. These shifts contributed strongly to changes in algal communities, with changes in zooplankton leading to strong top down effects that decreased algal production through increasing grazing pressure despite increasing nutrient concentrations. Our results suggest that the typical external drivers (climate and nutrients) of lake ecosystems may be suppressed by internal shifts in plankton communities in lakes.
... Our first hypothesis, consistent with many studies on saline lakes in different regions of the world [11][12][13][14], was confirmed. The number of pelagic zooplankton species decreased with the salinity increase. ...
... At the same time, the zooplankton species diversity was similar at a salinity range of 15-40 g L −1 . This observation partly coincides with the results by Lin et al. [11]. ...
... Previously, Lin et al. [11] proposed a conceptual model of salinity-related changes in the taxonomic structure of the zooplankton community. This model is very simplified and represents the change of zooplankton taxonomic structure with salinity increase as a sequence of Copepods and small cladocerans-Large cladocerans-Artemia. ...
Article
Full-text available
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 disappearance of fish, and in the change of the size distribution of phytoplankton particles with an increase in the proportion of cladocerans in the zooplankton. Even though we observed that with the salinity increase the food web in saline lakes transformed from three-trophic to two-trophic without fish, we conclude that in the salinity range from 10 to 20–30 g L−1 this transition in most cases will not increase the ability of zooplankton to control phytoplankton. Interactive effects of salinity and eutrophication strongly depend on the size and depth of the lake, as deep stratified lakes tend to have a better water quality with lower biomasses of both phyto- and zooplankton. Thus, the salinity per se is not the driver of the decline in water clarity or the uncontrolled development of phytoplankton. Moreover, for deep lakes, salinity may be a factor affecting the stability of stratification, which mitigates the consequences of eutrophication. Thus, small shallow lakes will be the most vulnerable to the joint effect of salinity increase and eutrophication with the degradation of ecosystem functioning and water quality at moderate salinities of 3–20 g L−1.
... On the Qinghai-Tibet Plateau (QTP), 40% of the land area is covered by permafrost (Zou et al., 2017), with thermokarst lakes extensively distributed (Niu et al., 2011;Luo et al., 2020). Although zooplankton communities in some large brackish lakes of QTP have been studied (Lin et al., 2017;Zhu et al., 2019;Liang et al., 2021), the spatial patterns of zooplankton communities in thermokarst lakes and their responses to environmental variation are largely unknown. In this study, our objectives were to answer two questions: ...
... Such low richness in our studied lakes is comparable to that of thermokarst lakes in high Arctic and subarctic regions, where the median taxonomic richness of crustacean zooplankton was previously reported as 3 and 5, respectively (Schartau et al., 2021). In large brackish lakes on the QTP, zooplankton also shows in low diversity (Lin et al., 2017;Zhu et al., 2019;Liang et al., 2021). For example, only 2 species of Cladocera and 3 species of Copepoda were reported in saline lake Namuka Co in Northern Tibet (Zhao et al., 2010). ...
... For example, the richness and density of both Cladocera and Copepoda were positively correlated with DO, which has been described previously as a strong factor affecting zooplankton community structure, diversity, and abundance (Patoine et al., 2002;Beisner et al., 2006;Wen et al., 2010). Previous studies of other Tibetan lakes also suggested that salinity is a main factor limiting zooplankton species diversity (Lin et al., 2017;Zhu et al., 2019). In our studied thermokarst lakes, however, conductivity (a substitute measure of salinity) was not correlated with zooplankton species richness. ...
Article
Full-text available
Global warming is accelerating permafrost thaw, forming new thermokarst lakes and substantially influencing the old ones. However, the biological communities in thermokarst lakes on the Qinghai-Tibet Plateau (QTP) are rarely studied. Here, we assessed the biogeographical patterns of zooplankton communities in 44 thermokarst lakes across the QTP. Across all lakes, 17 Cladocera and 13 Copepoda species were identified, with most of the lakes dominated by Cladocera. Chydorus sphaericus and Cyclops vicinus were the most frequently detected species. Both cladoceran and copepod communities had very low species richness and density, which lacked a clear spatial pattern but positively associated to dissolved oxygen. In general, species richness was negatively influenced by seston particle quantity while the density was positively influenced by water nutrient concentrations. Cladoceran and copepod communities had a high β-diversity (0.89 and 0.91, respectively), which was dominated by species turnover. However, Cladocera had significantly lower β-diversity and turnover component than copepod communities. β-diversity of Cladocera and Copepoda showed a significant but weak distance decay relationship and also significantly correlated with longitude, latitude, mean annual temperature, as well as concentrations of seston particle carbon and nitrogen. In addition, their β-diversities differentially correlated to other environmental variables. Overall, the results suggested that the geographical barriers, climate, and some local environmental variables are key factors in shaping the biogeography of zooplankton community. Although a general biogeographic pattern of zooplankton across the QTP cannot be drawn from this limited dataset, this study provided the first large spatial scale investigation and analyses of zooplankton biogeography in thermokarst lakes on the QTP. Given the important roles of zooplankton in aquatic ecosystems, this study could provide insights for understanding the influences of future environmental changes on thermokarst lake ecosystems.
... As a result of this increased meltwater, numerous lakes have expanded (Zhang et al., 2015) and lake levels have increased (Zhang et al., 2011). These thermal and hydrologic changes could have severe impacts on the structure and function of lake ecosystems (Lin et al., 2017). For instance, enhanced inputs of glacial meltwater can alter lake hydrology, salinity, enhanced stratification and nutrient regime, and thereby impede internal nutrient loading to limit algal blooms (Posch et al., 2012;Slemmons and Saros, 2012) and biodiversity (Milner et al., 2009). ...
... The trophic structure of most Tibetan lakes is relatively simple, with Daphnia tibetana and/or Artemia tibetiana forming the top trophic level in lakes without fish (Lin et al., 2017). Daphnia (Cladoceran) are known to be of pivotal ecological importance in lakes and ponds because they are large filter-feeding zooplankton that consume copious amounts and varieties of algae (Carpenter and Kitchell, 1996). ...
... The brine shrimp Artemia (Anostraca) has a broad geographical distribution inhabiting both inland and coastal saline and hypersaline lakes (Abatzopoulos et al., 1998). Salinity is an important driver of the distribution of these zooplankton in QTP, as Artemia tibetiana can survive salinities between 25 and 75 g/L, whereas Daphnia tibetana mainly survive between 5 and 28 g/L (Lin et al., 2017). Since the late 1970s, global commercial breeding of fish has led to increased human consumption of Artemia (Sorgeloos et al., 2001). ...
Article
Full-text available
Modelling, monitoring, and experimental data have shown that global climate change can impact aquatic phytoplankton communities directly, through the effects of warming on primary producers, as well as indirectly through cascading effects from higher trophic levels. Although both concepts are common in modern limnological studies, it remains unclear whether the ‘top-down’ effects from higher trophic levels on phytoplankton exert strong effects in natural systems over long (centennial) timescales. Here, we use multiproxy data including pigments, zooplankton remains, nutrient concentrations, and paleoclimate indicators from a sediment core in Dagze Co, Central Tibet (a two-trophic level lake) to reconstruct algal production, zooplankton community, nutrient and salinity changes. Our results show that top-down effects of higher trophic levels offset effects from warming and nutrient addition on algal growth. Warming enhanced glacial meltwater inflow to the lake, and intensive human activities increased nutrient inputs. Changes in lake salinity and N:P ratios coincided with zooplankton community shifts during the past 600 years, and Daphnia tibetana replaced the brine shrimp, Artemia tibetiana, after the relocation of a town to upstream of the lake in the 1980s led to overharvesting of the brine shrimp. These shifts contributed strongly to changes in algal communities, with changes in zooplankton leading to strong top-down effects that decreased algal production through increasing grazing pressure despite increasing nutrient concentrations. Our results suggest that the typical external drivers (climate and nutrients) of lake ecosystems may be suppressed by internal shifts in plankton communities in lakes.
... The Tibetan Plateau is the highest (average altitude above 4500 m a.s.l.) and the largest plateau on the Earth (Lin et al. 2017). Over 1000 lakes (area >1 km 2 ) are distributed across this plateau, most of which are land-locked saltwater lakes (Ma et al. 2011). ...
... Over 1000 lakes (area >1 km 2 ) are distributed across this plateau, most of which are land-locked saltwater lakes (Ma et al. 2011). Under the current background of global warming, the Tibetan Plateau is warming about three times faster than the global average (Lin et al. 2017). Plateau lakes and streams, with unique and diverse faunas, are among the world's most vulnerable aquatic ecosystems and are severely threatened by climate warming (Jiang et al. 2013, Tonkin et al. 2018). ...
... The water level of Qinghai Lake is rising, and the water area has increased in recent years owing to the increasing precipitation and accelerated melting of glaciers. Since 2005, water levels have increased over three meters (Lin et al. 2017). ...
Article
Full-text available
Deterministic and stochastic processes are two major factors shaping community dynamics, but their relative importance remains unknown for many aquatic systems, including those in the high‐elevation Qinghai–Tibet Plateau. Here, we explored the causes of multidimensional beta diversity patterns (i.e., taxonomic, functional, and phylogenetic) of a macroinvertebrate metacommunity in this large aquatic system by using multiple approaches (i.e., null models, phylogenetic signal testing, and ordination‐based approaches). To obtain insights into community assembly mechanisms, we also analyzed beta diversity in two deconstructed sub‐metacommunities (e.g., different tributaries and the main lake body). We found that most functional traits showed significant phylogenetic signals, indicating that the functional traits were profoundly influenced by evolutionary history. The null models showed randomness of functional and phylogenetic beta diversities for the whole basin and its tributaries, confirming the importance of stochasticity over deterministic processes in controlling community structure. However, both phylogenetic and functional community structures were clustered in the Qinghai Lake, probably reflecting the importance of environmental filtering. Ordination‐based approaches also revealed that both environmental factors and spatial processes accounted for variation in taxonomic, functional, and phylogenetic beta diversity. More specifically, environmental filtering was more important than spatial processes for the functional dimension, but the opposite was true for the taxonomic and phylogenetic dimensions. The paleogeographic history of the Qinghai Lake basin may have contributed substantially to the prevalence of stochastic processes. Overall, this study provides a better understanding of ecological patterns and assembly mechanisms of macroinvertebrate communities across this poorly known high‐elevation aquatic system that is highly sensitive to climate warming.
... Smaller animals (e.g., zooplankton) are more sensitive to salt than larger organisms (e.g., fish), but responses differ substantially among species (US EPA 1988;Castillo et al. 2018). For zooplankton, an increase in salinity has been linked to a reduction in species richness (Jeppesen et al. 2007;Lin et al. 2017). For example, as salinity increases in brackish lagoons, cladocerans, which play a crucial role in regulating phytoplankton, are often lost, and communities become dominated by copepod and rotifer species (Jeppesen et al. 2007 and references therein). ...
... However, where individuals are salt-limited, top-down control may be retained or enhanced with salinization. Though salinization reduced species richness in our experiment, our increase in zooplankton biomass was not driven by competitive release from Daphnia as found in other studies on road salts and from brackish waters (e.g., Jeppesen et al. 2007;Van Meter and Swan 2014;Lin et al. 2017). At salt concentrations above 500 mg Cl − L −1 , a copepod (E. ...
... However, shifts in body size may be more pronounced in systems with a top predator (fish, predatory macroinvertebrates). For example, in tri-trophic systems, topdown control by fish may reduce the density and the bodysize size of zooplankton communities via size-selective predation (Jakobsen et al. 2004;Lin et al. 2017;Gutierrez et al. 2018). Further, the presence of predators may increase zooplankton richness, as large-bodied cladocerans become less abundant at salt concentrations lower than predicted by salt toxicity alone, allowing a more diverse community to establish (Jensen et al. 2010). ...
Article
Full-text available
Runoff containing road salt (sodium chloride, NaCl) causes the salinization of inland freshwaters, with potentially severe impacts on aquatic species. We performed a mesocosm experiment to test the effects of salinization on plankton community structure in an oligotrophic mountain lake with a limited history of elevated salt concentrations. We exposed plankton communities to a gradient of 30 salt concentrations ranging from 1 to 2900 Cl− mg L−1 for 6 weeks. Adding salt increased zooplankton biomass at concentrations < 500 mg Cl− L−1 while reducing phytoplankton biomass. Zooplankton biomass declined precipitously at higher concentrations, with phytoplankton biomass showing a mirror image increase. The initial increase in zooplankton biomass with salt addition suggests that zooplankton are salt‐limited at low ionic concentrations. Additionally, the inverse response of zooplankton and phytoplankton suggests that salinity mainly affects phytoplankton biomass via changes in top‐down regulation by grazers.
... Among ongoing global changes, salinity modification in different water bodies is one of the most influential, affecting the structure, functioning, and dynamics of aquatic ecosystems [1][2][3][4]. This modification may have various causes (natural and anthropogenic) as well as different directions, either increasing or decreasing [5][6][7][8]. ...
... The same global change can lead to an increase in salinity in some water bodies and a decrease in others. For example, air temperatures increase, leading to an acceleration of melting of mountain glaciers, which causes a salinity decrease in lakes that are fed from these glaciers [6]; however, in other lakes, it may cause a salinity increase by increasing evaporation [2]. Anthropogenic influences also may strongly influence the salinity of water bodies, with a wide variety of ecosystems responding to them [9][10][11][12][13]. ...
Article
Full-text available
Lakes and lagoons play an important role worldwide, and salinity fluctuations significantly affect their ecosystems. Bay Sivash, the world’s largest hypersaline water body, underwent a sharp change in salinity, induced by the closing of the North Crimean Canal. To monitor a shift in the ecosystem, a study was carried out from 2014 to 2020 at 15 sites of the lagoon. Since the closure of the canal, the average salinity increased from 22 g L−1 (2013) to 94 g L−1 (2020). Suspended solids and dissolved organic matter also increased. When salinity increased above 50 g L−1, the number of taxa significantly decreased; this was a negative linear relation. The increase in salinity significantly changed the structure of zooplankton and benthos. The most dramatic changes occurred with the salinity increase from 25 to 70 g L−1. Chironomidae larvae numbers began to increase greatly in the ecosystem of the bay, and since 2014, they have rapidly increased their contribution to the abundance of benthos and plankton. The concentration of benthic–planktonic species increased in plankton, in particular, in Harpacticoida and Chironomidae. At salinity above 80–90 g L−1, nauplii and adult brine shrimp appeared to become abundant in plankton and benthos. The transit of the ecosystem to a new alternative state occurred.
... Ecosystems of shallow salt lakes, where changes in weather conditions can initiate a whole cascade of changes at different trophic levels, are especially sensitive to climatic fluctuations (Williams, 2002;Shadrin and Anufriieva, 2013). Significantly higher water salinity often reduces the number of links in their food chains and gives rise to the trophic cascade (Lin et al., 2017;Golubkov et al., 2018). In years with low atmospheric precipitation and high water salinity, which is favorable for the development of large crustaceans Artemia spp., their filtration activity can significantly reduce the primary production of plankton (Golubkov et al., 2007;Golubkov, 2012;Golubkov et al., 2018). ...
... High water salinity also enhances the role of prokaryotic organisms compared to eukaryotic ones, as well as that of anoxygenic photosynthesis and chemosynthesis compared to oxygenic photosynthesis (Shadrin and Anufrieva, 2018). In general, higher water salinity as a result of climate aridization in mid-latitudes can lead to dramatic changes in biodiversity, primary productivity, shorten-ing of the food chain, and reduced efficiency of energy transfer from producers to upper trophic levels in salt lakes (Williams, 2002;Lin et al., 2017;Golubkov et al., 2018;Shadrin and Anufrieva, 2018). ...
Article
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Climatic fluctuations are among the most important factors that cause changes in terrestrial and aquatic ecosystems. This review considers the principal mechanisms of the influence of climate changes on the structure and functioning of ecosystems of water bodies and shows the need to take these mechanisms into account when developing strategies for conserving the biological resources of aquatic ecosystems. Climatic fluctuations affect aquatic ecosystems through changes in temperature, surface runoff of nutrients and other substances and their ratios, the intensity of water mixing during the circulation period, and other mechanisms. Additional nutrients received in rainy periods from the catchment area and directly with precipitation stimulate the growth of primary producers and cause the risk of the further eutrophication of water bodies. An increase in temperature promotes the growth of potentially toxic phytoplankton species and exacerbates the problem of green tides, the massive development of multicellular algae in the coastal zone. Organic substances coming from the catchment area during wet periods stimulate a microbial loop in aquatic ecosystems. In shallow lakes, climate fluctuations can cause changes in food webs and the ecological regime. Climate-induced changes in the composition of producer communities often weaken pelagic-benthic relationships in aquatic ecosystems. In some cases, climate changes have contributed to the invasions of alien species. The natural dynamics of ecosystems affected by climate fluctuations deserves close attention and requires the development of special adaptive management of aquatic biological resources. In some cases, it is necessary to take more severe measures for the protection and restoration of water bodies, which would take into account adverse changes in natural factors.
... However, current understanding of how salinity change in aquatic environments will impact zooplankton communities is mostly limited to the salinization of freshwater environments (e.g. Hintz et al., 2017;Lin et al., 2017;Moffett et al., 2020), estuaries (e.g. Gao et al., 2008) or single-species responses (e.g. ...
... Cervetto et al., 1999), while community-level changes and consequences for food web interactions in marine environments remain poorly understood. Studies on the effects of salinization of freshwater environments, have reported a range of responses including, dominance shifts and disruption of trophic interactions (Lin et al., 2017;Gutierrez et al., 2018). These results imply that a similar response to salinity change could be expected in marine environments. ...
Article
Full-text available
Climate change predictions indicate global changes in salinity with negative implications for plankton food webs; an important baseline for functioning of marine ecosystems. Current understanding of how salinity change will impact plankton communities is mostly limited to the salinization of freshwater environments, with little known about the effects of changing salinity in marine systems. In this study, we investigate the effect of salinity change on zooplankton communities under different salinity change scenarios of the Baltic Sea. Projections for future salinity change derived from regional physical-biogeochemical models were used to set-up an outdoor mesocosm experiment in the coastal area of the Gulf of Finland. Each mesocosm was inoculated with natural plankton using a mixture of both marine and freshwater communities, mimicking the natural influx of freshwater species from rivers into the Baltic Sea. Zooplankton diversity and composition changed possibly due to different salinity tolerances among the species. Among zooplankton, rotifers dominated in low salinities (74%) and cladocerans and copepods (69%) in high salinities. Our results suggest that the zooplankton community will shift to a rotifer dominated community in areas with declining salinity due to the intolerance of other zooplankton groups to freshening.
... Alternatively, some microbes can reduce nitrate to ammonium via dissimilatory nitrate reduction to ammonium (DNRA), and retain N as a more bioavailable form (Burgin and Hamilton 2007;Giblin et al., 2013). Therefore, understanding the nitrate reduction, whether it is removed (via denitrification) or retained (via DNRA), have far-reaching implications for evaluating and predicting the N fate in aquatic ecosystems (Dong et al., 2011;Jiang et al., 2020;Nizzoli et al., 2010;Scott et al., and semiarid lakes (Brucet et al., 2012;Lin et al., 2017). Lakes in arid or semiarid region are usually naturally saline, as the evaporative concentration process leads to progressive salt accumulation (Wurtsbaugh et al., 2017;Yapiyev et al., 2017). ...
... It is well known that salinity fundamentally shapes the structure and function of lake ecosystems (Brucet et al., 2012;Dugan et al., 2017;Lin et al., 2017). The change in salinity can cause decreases or increases in cytoplasmic volume through imposing considerable osmotic and matric stress on the involved microbes, resulting in the loss of metabolic activity (Neubauer et al., 2019;Zaghmouri et al., 2018;Zhao et al., 2013). ...
Article
Salinization caused by climate change and nitrogen (N) pollution are both important environmental threats for inland lakes. However, evaluating their interactive effects continues to be challenging. Here, field observation and microcosmic experiments were conducted in six lakes of East Asia with the different salinity and climate characteristics, to explore the response of the key N cycle processes related to N fate to the climate-induced change in salinity. The results indicated that increased salinity inhibited denitrification, which was the outcome of two cumulative effects: the long-term microbial adaptation effect and the direct salinity stress. Whereas increased salinity had unsignificant or positive effects on dissimilatory nitrate reduction to ammonium. It had caused that N retention capacity is relatively stronger in saline than freshwater lakes. Inland lakes are long-term basin-wide integrators of climatic conditions that drying (salinization) and wetting (desalination) with climate change. In semi-arid regions of East Asia, lake shrinkage, salinization and increasing temperature driven by climate warming and drying may exert a negative impact on N pollution through concentrating, decreasing denitrification and increasing ammonium release from sediment. The threat of climate change on these lakes is not just the quantity of water, but its quality.
... The structure of food webs changes from high complexity in mesosaline lakes with multiple trophic levels with fish as top predators and diverse pelagic and littoral invertebrate assemblages (Hurlbert et al. 1986, Hammer 1993 to simplified food webs in hypersaline lakes with amphipods as top predators and a shorter food web length (Lin et al. 2017, Golubkov et al. 2018, Jeppesen et al. 2020, Shadrin and Anufriieva 2020. Studies using stable isotope analysis suggest a declining food web complexity with increasing salinization (Cooper and Wissel 2012). ...
... The shifts in trophic structure and food web complexity with increasing salinity are, however, neither simple nor linear. For example, abrupt shifts can occur at specific salinity thresholds (Williams 1998, Brucet et al. 2009, Lin et al. 2017, Jeppesen et al. 2020. Changes in size structure of fish have been observed as a negative effect of increasing salinity (e.g., decrease in mean and maximum size; Sgarzi et al. 2020). ...
Article
The Andalusian International University held a workshop entitled Temporary wetlands’ future in drylands under the projected global change scenario in March 2020 in Baeza, Spain, with 26 participants from 10 countries. The workshop objectives were to promote international cooperation and scientific exchange on the conservation and protection of temporary wetlands. The participants highlighted the extreme conditions that temporary and permanent wetlands, ponds, and shallow lakes are currently facing and predicted a dismal future for these systems due to climate change. To foster a holistic view of these ecosystems, the workshop included wetland watersheds. It was concluded that the main threats are those affecting water quality and quantity as well as egg-seed banks, species population dynamics, and food webs. The inherent characteristics of waterbodies in drylands, including high resilience and resistance to harsh conditions, are already negatively impacted by direct human actions and climate change. Another threat is the time lag between scientific warnings about threats and the social and political concern leading to mitigating actions. Thus, more effective actions to protect and conserve temporary wetlands are essential. Research networks could help stimulate the necessary conservation actions, but the global recession due to the COVID-19 pandemic will pose a challenge as economies are burdened with urgent expenditure.
... Additionally, salinity, acting as an environmental filter, can reshape the trophic structure of lake systems (Williams, 1998). The trophic structure of lake systems on the Qinghai-Tibet Plateau changes from freshwater to salt lakes, changing in grade from a level 3 to a level 2 food chain (Lin et al., 2017). The lack of a high trophic level (e.g., fish) in high-salinity lake systems strengthens the topdown control of phytoplankton by zooplankton, resulting in a decrease in phytoplankton biomass (Gutierrez et al., 2018). ...
... Due to the different responses of phytoplankton communities to increases in TN concentrations along salinity gradients, land-use types consequently accelerated the succession of phytoplankton communities in different directions. For saline lake systems comprised of a simple nutrient structure, ecological risks were aggravated (Lin et al., 2017). ...
Article
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The Qinghai-Tibet Plateau is the highest and largest plateau in the world and is composed of the world’s greatest clustering of plateau lake systems. Given their extreme environmental conditions and simplistic trophic structures, certain phytoplankton species endemic to these lakes are extremely sensitive to changes in nutrients. Understanding the different response of phytoplankton communities to nutrients along different environmental gradients will help us devise appropriate ecological protection measures specific to individual lake conditions. This study investigated characteristics of phytoplankton communities and associated environmental factors in 20 alpine lakes, ranging in altitude from 2500 m to 4500 m. Results showed that salinity was the critical controlling factor in all phytoplankton communities, while also hindering phytoplankton abundance and biomass without changing the dominant species of algae. Results also showed that altitude was an important driving factor for variation in individual phytoplankton size, which was endemically smaller than phytoplankton size in low-altitude lakes. Moreover, the phytoplankton community response to nutrients differed under different salinity gradients. In addition, water nitrogen (N) concentrations can alleviate salinity limitations on dominant phytoplankton species in saline lakes (salinity > 35‰) while aggravating those in saltwater lakes (1‰ < salinity < 35‰). It is imperative to improve our understanding of climate change and anthropogenic impacts on carbon (C) fixation capacities of plateau lake systems into the future.
... The pace of warming is especially remarkable on the Tibetan Plateau (TP) (Qiu, 2008), the world's highest mountain region. Outstanding climate change on the TP has caused recession of glaciers (Yao et al., 2012), degradation of permafrost (Wu and Zhang, 2008) and changes in terrestrial plants (Liang et al., 2016), all of which are expected to impact the freshwater ecosystems (Chen et al., 2014;Hu et al., 2014;Lin et al., 2017;Tao et al., 2018). Therefore, there is an urgent need to assess the status and development of mountain freshwater ecosystems in the context of global climate change (Hock et al., 2019;Wagner and Adrian, 2009). ...
... 1083e1180 CE and a notable increase in the period of 1690 CE to the present were related to the Medieval Climate Anomaly (MCA) and the CWP. For unicellular organisms, cell size is considered to be the "master trait" that impacts growth, metabolism, access to resources and predator avoidance (Litchman and Klausmeier, 2008;Svensson et al., 2014). The Temperature-Size Rule (TSR) is ubiquitous, describing a negative effect of temperature warming on body size of species including uni-and multicellular groups from individual to community structure levels (Daufresne et al., 2009;Finkel et al., 2009a;Forster et al., 2013). ...
Article
Climate change on the southeastern Tibetan Plateau (TP) is assumed to impact lake ecosystems. However, parallel changes in climate and non-climate factors and mediation of signals by catchment processes complicate the assessment of climate-change effects on lake ecosystems requiring long-term and high resolution multi-variable time-series. Here we present a diatom record from sediments in the lake Basomtso, southeastern TP, covering the period 1083–2012 CE with sub-decadal resolution which we relate to available proxies for potential climate and non-climate factors. The record is dominated by planktonic species and the compositional change is mainly characterized by alternations between big- and small-celled Pantocsekiella ocellata and between planktonic and benthic diatom species. The diatom assemblages show a decrease of P. ocellata (big form) since the end of 17th century and an increase of P. ocellata (small form) as well as an increase in diatom productivity, reflecting changes on a centennial timescale which mainly follow temperature increase. We recorded several changes in the ratio of planktonic to benthic species abundance (P: B) on a sub-decadal or decadal timescale. Noticeable decreases in P: B were a result of rapid sedimentary events caused by high energy flows. Cross-correlation analyses reveal synchronous responses of diatoms and asynchronous responses of terrestrial vegetation to regional temperature change, indicating a higher potential of lake diatoms to detect the timing and magnitude of climate shifts on the southeastern TP. The results imply that aquatic ecosystems in Basomtso, as well as in other mountain lakes on the southeastern TP, are probably subject to a larger risk of regime shift than terrestrial ecosystems under future climate scenarios.
... Seasonality and local ecological factors such as salinity and wetland size have strong effects on cestode prevalence and abundance. Future studies are needed to understand how avian cestodes are distributed at macroecological scales, and how they respond to global change such as ongoing salinization of wetlands [64], and changing migration patterns of waterbirds [65]. ...
Article
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Further biogeographical studies of parasites are vital to improve our understanding of biodiversity distribution and predict the impacts of global change. Hypersaline lakes are good laboratories to investigate the avian cestode abundance and species diversity given the abundance of hosts (waterbirds and Artemia) and their broad latitudinal distribution. We analysed cestode infection in brine shrimp Artemia franciscana in northern (Atacama) and central Chile and compared them to results from A. persimilis in southern Chile (Patagonia). Thus, we covered a broad latitudinal gradient from 23° to 53° S. Five cestode taxa including two species of the genus Flamingolepis, Gynandrotaenia stammeri, Eurycestus avoceti, and Fuhrmannolepis averini were recorded from A. franciscana in Atacama lagoons (prevalence = 4.1%). In contrast, no cestode infection was detected in central Chile, likely because they are temporary wetlands. Parasites of flamingos and shorebirds were associated with Atacama lagoons (arid and higher salinity), while Confluaria podicipina and Fimbriarioides sp. (parasites of grebes and ducks, respectively) were dominant in Patagonian lagoons (sub-antarctic and of lower salinity). These differences mirror changes in the relative abundance of the respective final hosts. The flamingo parasite Flamingolepis sp. 1 was the most prevalent and abundant cestode in Atacama, where it was recorded only in autumn. Seasonality and habitat effects (especially abundance and phenology of different bird species) appear to override any latitudinal trends in the prevalence, diversity, and distribution of cestodes. Cestode prevalence was higher in larger wetlands but was not related to the sex of either intermediate host. We recorded a greater taxonomic richness at the cestode family level in Atacama, but a greater dominance of a single family of avian hosts (the flamingos). Ours is the first spatio–temporal study of Artemia cestodes at local and regional scales in the southern hemisphere.
... Rotifers usually display r-strategy life histories and are adaptable to environmental disturbances [48]. Meanwhile, temperature can restructure food webs, changes food resources (e.g., phytoplankton) and predators (e.g., fish) quantitively and qualitatively, imposing indirect effects on zooplankton ultimately [49][50][51]. In this study, T and Chl a show highly significantly positive correlation (r = 0.46, p = 0.006, not shown in Fig 7 because of high collinearity with T and COD Mn ), implying indirect effects of T according the predator-prey relationship mediated by Chl a. ...
Article
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To expand the knowledge on the tempo-spatial patterns of zooplankton and the key modulated factors in urban aquatic ecosystem, we investigated zooplankton and water quality from April 2018 to January 2019 in the hinterland of the Three Gorges Reservoir area, Wanzhou City of China. The results indicated that water quality indicated by the trophic state index (TSI) reached a state of mesotrophication to light eutrophication in the Yangtze River, and a state of moderate- to hyper- eutrophication in its tributaries. Based on the biomass of zooplanktons, Asplanchna priodonta was the most common specie in April; Encentrum sp., Filinia cornuta and Epiphanes senta were the most noticeable species in summer; Cyclopoida Copepodid, Sinocalanus dorrii and Philodina erythrophthalma became the dominant species in winter. Generally, rotifers prevailed in April and August, and copepods became the most popular in January. According to canonical correspondence analysis, nitrate, temperature (T), ammonia, water level and permanganate index (COD Mn ) significantly influenced the community structure of zooplankton ( p < 0.05). The dominant species shifts of zooplankton were partly associated with nutrient level (nitrate and ammonia) under periodic water level fluctuations. Rotifers and protozoans were characterized as high T adapted and COD Mn -tolerant species comparing with cladocerans and copepods. The ratio of microzooplankton to mesozooplankton (P micro/meso ) has presented a strongly positive relationship with T ( p < 0.001), as well as P micro/meso and COD Mn ( p < 0.001). It implied that zooplankton tended to miniaturize individual size via species shift under high T and/or COD Mn conditions induced by global warming and human activities. The information hints us that climate change and human activities are likely to produce fundamental changes in urban aquatic ecosystem by reorganizing biomass structure of the food web in future.
... The Qinghai-Tibet Plateau as the roof of the world and the water tower of Asia is a significant ecological security barrier. Its fragile ecological problems, including freezethaw erosion [39], hydraulic erosion [40], land desertification [41], and salinization [42], make the alpine ecoregion of the Qinghai-Tibet Plateau an area with the most apparent ecological vulnerability [43]. Current studies on the Qinghai-Tibet Plateau mainly focus on land-use changes and grassland resources [44][45][46]. ...
Article
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Changing land-use patterns in the Qinghai–Tibet Plateau (QTP) due to natural factors and human interference have led to higher ecological vulnerability and even more underlying issues related to time and space in this alpine area. Ecological vulnerability assessment provides not only a solution to surface-feature-related problems but also insight into sustainable eco-environmental planning and resource management as a response to potential climate changes if driving factors are known. In this study, the ecological vulnerability index (EVI) of Shannan City in the core area of the QTP was assessed using a selected set of ecological, social, and economic indicators and spatial principal component analysis (SPCA) to calculate their weights. The data included Landsat images and socio-economic data from 1990 to 2015, at five-year intervals. The results showed that the total EVI remains at a medium vulnerability level, with minor fluctuations over 25 years (peaks in 2000, when there was a sudden increase in slight vulnerability, which switched to extreme vulnerability), and gradually increases from east to west. In addition, spatial analysis showed a distinct positive correlation between the EVI and land-use degree, livestock husbandry output, desertification area, and grassland area. The artificial afforestation program (AAP) has a positive effect by preventing the environment from becoming more vulnerable. The results provide practical information and suggestions for planners to take measures to improve the land-use degree in urban and pastoral areas in the QTP based on spatial-temporal heterogeneity patterns of the EVI of Shannan City.
... For instance, changes in nutrient availability affect the community structure of aquatic organisms both directly and indirectly (Bini et al., 2014;Zhang et al.. 2014;Azevêdo et al., 2015). On the one hand, different taxa may be directly filtered through the changing environmental conditions, and different taxa have different tolerance to nutrient concentration (Smith et al., 1999;Lin et al., 2017;Zhang et al., 2019). On the other hand, eutrophication-driven changes affecting the producers and decomposers (Interlandi and Kilham, 2001;Gianuca et al., 2017) may cascade through the food chain indirectly affecting consumers (Heip, 1995;Binzer et al., 2016), called the bottom-up effect (Pace et al., 1999). ...
Article
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Eutrophication is a major problem currently impacting many surface water ecosystems. Impacts of increased nutrient concentrations on biodiversity may differ between different scales, different organism groups, and different trophic states. Surveys at different spatial scales have suggested that biodiversity of different taxa may exhibit significant cross-taxon congruence. In our study, we examined the diversity of zooplankton and zoobenthos across 261 lakes in the Lake Taihu watershed, an area that is undergoing a severe eutrophication process. We tested the cross-taxon congruence in species richness and Shannon-Wiener diversity between zooplankton and zoobenthos along a nutrient gradient across the lakes. Our findings were consistent with the intermediate disturbance hypothesis, considering nutrient input as the disturbance. Also, we found significant cross-taxon congruence between zooplankton and zoobenthos diversities. Our results confirmed that excess nutrient levels resulted in diversity loss and community simplification. Zoobenthos were more sensitive to nutrient increases compared with zooplankton, which decreased cross-taxon congruence because these organism groups did not respond similarly to the anthropogenic disturbance.
... В 20 и 21 веках наука накопила множество данных, показывающих, что сообщества, экосистемы и популяции могут существовать в более чем в одном устойчивом состоянии. Это показано в результате исследования разных экосистем, в частности, пресноводных и соленых озер (Blindow et al., 1993;Scheffer, 2001;Dent et al., 2002;Davis et al., 2003;Загородняя и др., 2008;Capon et al., 2015;Lin et al., 2017;Shadrin, 2018), рек (Dent et al., 2002;Богатов, 2013) и лесов (Dublin et al., 1990;Staver et al., 2011;Kitzberger et al., 2016). Для различных типов морских и прибрежных экосистем имеется также немало исследований, показавших наличие альтернативных состояний (Knowlton, 1992;Petraitis, Dudgeon, 2004;Norström et al., 2009;Petraitis et al., 2009;Shadrin et al., 2012;McGlathery et al., 2013;Feehan, Scheibling, 2014). ...
Article
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Currently, the destruction of landscapes is taking place with a decrease in the sustainability and productivity of natural ecosystems. One of the main reasons for this is inadequate environmental management, which, as a rule, is based on inadequate outdated theoretical ecological concepts. The totality of accumulated data shows that real ecosystems can be in several alternative states and demonstrate relatively rapid changes in the regime of existence with significant, abrupt and permanent changes in structure and functioning. In this regard, the main ecosystem paradigm is currently being revised. From the theoretical concept of the unicity of the ecosystem stable state, ecology moves to the concept of the multiplicity of stable states in the ecosystem. The dynamics of ecosystems can be represented, according to K. Holling, in the form of an adaptation cycle with the alternation of four phases, the features of which are considered. The importance of no return points and possible uncertainty in the dynamics of ecosystems are shown. Ecosystems, in a certain sense, have memory, which is the reason for the hysteresis effect during multidirectional changes in systems. The necessity of developing approaches of adaptive ecosystem management based on this concept is shown. Which is especially important in cases of rapid transformation of natural ecosystems, such, as an example, in the Crimea after the cessation of the supply of Dnieper water to the North Crimean canal. The difficulties of transition to adaptive environmental management in modern conditions are analyzed.
... Zooplankton have been widely suggested as an important indicator of the ecological status of lakes as they are affected by changes in both top-down and bottom-up control and may have a strong effect on water clarity (Carpenter et al., 2001;Jeppesen et al., 2011;Yuan and Pollard, 2018). The diversity and abundance of zooplankton are an indicator of water quality and trophic conditions in both cold, temperate and tropical waters (Barnett and Beisner, 2007;Lin et al., 2017;Jeppesen et al., 2000;Kuczyńska-Kippen and Joniak, 2016;Lopes et al., 2014). Thus, understanding how zooplankton community composition varies over space and time (i.e., beta diversity) has become a central topic in lake ecology and management Loewen et al., 2019;Lopes et al., 2017;Soininen et al., 2007). ...
Article
Seasonal and annual dynamics of the zooplankton community in lakes are affected by changes in abiotic drivers, trophic interactions (e.g., changes in phytoplankton and fish communities and abundances) and habitat characteristics (e.g. macrophyte abundance and composition). However, little is known about the temporal responses of the zooplankton community to abiotic and biotic drivers across lakes at the regional scale. Using a comprehensive 20-year dataset from 20 Danish lakes in recovery from eutrophication, we assessed the seasonal and annual trends in the spatial heterogeneity of zooplankton community across lakes and related it to abiotic and biotic drivers. We found significant seasonality and inter-annual decreases in spatial zooplankton heterogeneity in both shallow and deep lakes, with the decrease in the spatial turnover dominating the temporal dynamics of the beta diversity. For the inter-annual changes, decreased spatial heterogeneity of phytoplankton, macrophytes and fish were important biotic drivers at the regional scale. Using a series of ordinary least squares regressions and model selection with model averaging approaches, we revealed that both local (e.g., total phosphorus, total nitrogen, pH, Secchi depth, alkalinity, Schmidt stability, water temperature) and regional drivers (e.g., air temperature, solar irradiance) were important variables influencing the spatial zooplankton heterogeneity, although the directions depended on the beta diversity measures and water depth. Our results highlight an important role of bottom-up forces through phytoplankton community as well as macrophytes and top-down forces via fishes in driving the temporal changes in zooplankton community composition patterns at the regional scale.
... Significant variations in the values of fundamental environmental parameters such as salinity can cause distinct differences in biocenotic structure and relationships among taxa within a single trophic level or even in the entire food web. This refers to zooplankton organisms because of their short life cycles (Allan, 1976) and the susceptibility of their species structure to salinity (Lin et al., 2017;Gutierrez et al., 2018). Consequently, several studies are showing that zooplankton species diversity can be a good indicator of the prevailing conditions in coastal lakes and lagoons (Rasuole, 2000;Brucet et al., 2009;Araújo et al., 2014;Oda et al., 2018). ...
Article
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The main purpose of the research was to determine the differences in the network relationships among zooplankton predator and prey taxa biomasses as a premise for dividing coastal lakes according to the brackish-freshwater gradient. Furthermore, the significance of these divisions in the overall interspecies interactions of the zooplankton networks of these waters was demonstrated. To solve problems with multidimensional and highly interactive character of the data, we used machine learning and meta-network analysis models. The data analysis methods comprised the support vector machines (SVM) multidimensional modelling, structural equation modelling (SEM), and graph network analysis. The zooplankton taxa biomasses showed high accuracy with lake classification on mesohaline, oligohaline and freshwater classes. We showed two interspecies relationships in coastal lakes in the zooplankton taxa predator–prey Cladocera and Copepoda - Rotifera assemblage, which variability of taxa biomass indicated more saline or more freshwater lake classes. Biomass increases in the predators Cyclopoida copepodites, B. longirostris, D. cucullata, and the prey K. cochlearis were associated with the freshwater class. However, increased Calanoida nauplii and his prey K. cochlearis tecta biomasses suggested that they belong to the more saline lake class. In the case of decreases in the biomass of these taxa, the preference would shift to the opposite of the above. Lake salinity classes differed in the role they had on the connections of the zooplankton taxa generalized meta-network of the South Baltic coastal lakes. The freshwater and mesohaline classes were the most important for the organization of the interspecies network, while the oligohaline class had the poorest connections among taxa and showed a marginal role in the integrity of the coastal lakes’ zooplankton meta-network.
... The present study was undertaken on the analysis of seasonal changes in the zooplankton structure and community influenced by the parameters in the sacred lake Prashar of Himachal Pradesh during the period of November 2014 to October 2015. Studies on zooplankton of lake have been done by some workers in different parts of the World [5][6][7][8][9][10][11][12] . Studies on lakes zooplankton have been done by some workers in different parts of India [13][14][15][16][17][18] . ...
Article
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In order to study the seasonal trends of zooplankton structure and community of the Prashar Lake, samples were collected in each month during one annual cycle (November 2014 to October 2015). A total of 27 genera of five zooplankton groups were identified during the study period. The zooplankton diversity belonging to five groups revealed 38% contribution of Rotifera followed by Cladocera (26%), Protozoa (25%), Copepoda (6%), and Ostrocoda (5%). The highest zooplankton abundance was observed in winter and the lowest in monsoon season. Among zooplankton, particularly Rotifera and Cladocera were the dominant groups throughout the study period. Maximum Shannon-Wiener diversity index was recorded at S2 compared to both S1 and S3. Correlation coefficients between physicochemical variables and zooplankton groups were calculated for assessing interrelationships using SPSS software.
... Salinity is used to describe the content of dissolved inorganic salt in water bodies. Saline water may also exert an influence on Chl-a concentrations through possible regulation of cell division and algae development (Ding et al. 2013;Desmit, Ruddick, and Lacroix 2015;Lin et al. 2017). To investigate the actual impact of salinity on the lakes in the TP, group difference analyses were conducted (Figure 7b, 7d). ...
Article
As essential parts of the unique ecosystem of Tibetan Plateau (TP), the sizes and associated physical properties of alpine lakes have long been investigated. However, little is known about one of the most critical biogeochemical properties, i.e. the Chlorophyll-a (Chl-a) concentrations. Here, for the first time, we presented a comprehensive investigation of the temporal–spatial variations in Chl-a in 82 lakes (>50 km²) across the entire TP region, based on MODIS observations in the period of 2003–2017. The results showed that the 82 lakes exhibited an average long-term mean Chl-a of 3.3 ± 4.3 mg m⁻³, with high Chl-a lakes concentrated in the eastern and southern inner TP basin and northeastern parts of the TP. An interannual trend analysis revealed that lakes exhibiting (significantly) decreasing Chl-a trends and (significantly) increasing Chl-a trends were comparable in numbers but differed in distribution patterns. A correlation analysis indicated that at least 70% of the interannual variability in Chl-a values of lakes was significantly correlated with one of the four environmental factors (wind speed, ice cover duration, lake water surface temperature and surface runoff) and lake size. In addition, glacier meltwater tended to reduce lake Chl-a while salinity levels showed minor influences.
... Over the past~10-20 years, there have been an increasing number of observational studies of the water quality effects of drought in freshwater systems on a global scale (Mosley, 2015). Salinization poses a serious threat to lakes because lake salinity plays a significant role in determining community composition (e.g., zooplankton, phytoplankton and plant-associated macroinvertebrate taxa) and lake ecosystem structure and dynamics (Brucet et al., 2012;Lin et al., 2017;Sereda et al., 2011). Enhanced salinity affects chemical structures, causing ionic imbalance in salt-sensitive biota, inhibiting their reproduction and leading to a decrease in biomass and diversity (Bezirci et al., 2012;Jeppesen et al., 2007). ...
Article
The rising temperatures, increased evaporation, and altered precipitation patterns associated with global warming pose threats to aquatic ecosystems, especially the salinization of lake water and changes in the terrestrial carbon budget. We studied a series of samples of catchment soils, surface sediments, and sediment cores from 51 lakes and reservoirs covering an extensive climatic range in northeastern China. Measurements included salinity indices (electrical conductivity and pH) and other physicochemical parameters, including magnetic properties and color (chroma). The results indicate that the occurrence of salt minerals and the salinity of the lake sediments are dominated by the arid climatic conditions of the region. This enabled us to develop climatic transfer functions between salinity, precipitation and evaporation, with potential applications in paleoclimatic research. As carbonates are the dominant salts in most of the studied lakes and reservoirs, past salinity variations are likely reflected by changes in HCO3 - and CO3 2- concentrations, which provides the opportunty to study the response of water-CO2-carbonate interactions to climate change. Our findings emphasize the important role of alkaline lakes in carbon burial and carbon neutralization, in the context of ongoing global warming.
... The removal of N in these ecosystems depends mainly on the self-purification capacity of the system (Valiente et al., 2018) because they are land-locked drainage networks (Yapiyev et al., 2017). Increased temperature and salinity in arid endorheic lakes due to climate change is introducing new challenges for these aquatic ecosystems that may impact how Nr is removed (Tao et al., 2015;Greaver et al., 2016;Lin et al., 2017). In a endorheic lake in Northwest China, Jiang et al. found that lake sediments had a high potential for the use of denitrification as a way to efficiently remove N from sediments. ...
... Water conductivity is usually related to salinity, which strongly affects zooplankton communities [44,45]. Zooplankton species richness decreased with lake salinization in the lakes of Tibet, and the zooplankton community shifted from the dominance of copepods and small cladoceran species to large saline filter-feeding cladocerans and phyllopod species [46] A similar pattern emerged in our study, which dominant cladoceran species in our sand ponds shifted from smaller C. reticulata to larger M. cf brachiata. Salinity is a serious stress factor for freshwater cladocerans, thus, species must either adapt to it or perish. ...
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In deserts, pond cladocerans suffer harsh conditions like low and erratic rainfall, high evaporation, and highly variable salinity, and they have limited species richness. The limited species can take advantage of ephippia or resting eggs for being dispersed with winds in such habitats. Thus, environmental selection is assumed to play a major role in community assembly, especially at a fine spatial scale. Located in Inner Mongolia, the Ulan Buh desert has plenty of temporary water bodies and a few permanent lakes filled by groundwater. To determine species diversity and the role of environmental selection in community assembly in such a harsh environment, we sampled 37 sand ponds in June 2012. Fourteen species of Cladocera were found in total, including six pelagic species, eight littoral species, and two benthic species. These cladocerans were mainly temperate and cosmopolitan fauna. Our classification and regression tree model showed that conductivity, dissolved oxygen, and pH were the main factors correlated with species richness in the sand ponds. Spatial analysis using a PCNM model demonstrated a broad-scale spatial structure in the cladoceran communities. Conductivity was the most significant environmental variable explaining cladoceran community variation. Two species, Moina cf. brachiata and Ceriodaphnia reticulata occurred commonly, with an overlap at intermediate conductivity. Our results, therefore, support that environmental selection plays a major role in structuring cladoceran communities in deserts.
... Tibet Plateau is the area that has the most lakes in China. According to statistics, there are more than 1,500 lakes in Tibet, most of which are salt lakes [31], and more than 97% are inland lakes [32]. According to the distribution characteristics of river systems and lakes, the lakes in Tibet can be divided as the out ow lake area in southeast Tibet; the out ow-inland lake area in southern Tibet; the inland lake area in northern Tibet. ...
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Background: Lake is a critical part of Tibet's hydrological cycle, the lake-terrestrial ecotone is the most sensitive area in the water and terrestrial ecosystem. For the ecological protection and maintenance of the lakeside zone, defining the upper boundary of the lake-terrestrial ecotone is a key issue that needs to be solved urgently. However, the ecological characteristics of lake-terrestrial ecotone made it diffcult to delimit. Wetland herbs are characteristic plants of the radiant belt toward the land of the lake-terrestrial ecotone, and their distribution range can be used to reflect the upper boundary of the lake-terrestrial ecotone. We took Baksum Lake, Yambdroktso, Namtso, Siling Co as examples, based on the spatial structure of the lake-terrestrial ecotone, used the moving split-window technology (MSWT) delimited the range of wetland herbs. Results:The results of MSWT showed the distribution range of wetland herbs in each lake-terrestrial ecotone with the natural-wetland type sampling line of Baksum Lake, Yambdroktso, Namtso, Siling Co was 51m, 56m, 33~53m, 19~31m. DCA showed number of wetland herbs species,BK1>YT1=NT1>NT2>SC1=SC2. PCA, RDA showed SMO, pH, SSC, and soil nutrient content had obvious correlation with distribution range. Conclusion:MSWT was a feasible method to delimit the distribution range of wetland herbs. SMO, pH, SSC, and soil nutrient content were all-important environmental factors affect the wetland herbs distribution range of the four lakes, however, the SMO was the most important factor. Besides, compare with the lakes in the lower Yangtze Plain,the high-density population distribution,high-intensitive human activity invaded the plants' growth area, resulting in a smaller distribution range.
... The effects of freshwater salinization (FS) on biological communities can lead to trophic cascades with implications for ecosystem functioning Hintz and Relyea, 2019;Lin et al., 2017;Vidal et al., 2021). Within this context, zooplankton is a key component of lake food webs, since it facilitates energy transfer by grazing on phytoplankton (Hébert et al., 2017;Jeppesen et al., 2010). ...
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Freshwater ecosystems are becoming saltier due to human activities. The effects of increased salinity can lead to cascading trophic interactions, affecting ecosystem functioning and energy transfer, through changes in community and size structure. These effects can be modulated by other environmental factors, such as nutrients. For example, communities developed under eutrophic conditions could be less sensitive to salinization due to cross-tolerance mechanisms. In this study, we used a mesocosm approach to assess the effects of a salinization gradient on the zooplankton community composition and size structure under eutrophic conditions and the cascading effects on algal communities. Our results showed that zooplankton biomass, size diversity and mean body size decreased with increased chloride concentration induced by salt addition. This change in the zooplankton community did not have cascading effects on phytoplankton. The phytoplankton biomass decreased after the chloride concentration threshold of 500 mg L⁻¹ was reached, most likely due to direct toxic effects on the osmotic regulation and nutrient uptake processes of certain algae rather than as a response to community turnover or top-down control. Our study can help to put in place mitigation strategies for salinization and eutrophication, which often co-occur in freshwater ecosystems.
... Recent studies demonstrate that freshwater ecosystems, even in high latitude and altitude areas, face multiple stressors produced by human activities and the global climate change (Smol et al., 2005;Anderson et al., 2013Anderson et al., , 2014Zhang et al., 2017;Jeff et al., 2019;Liang et al., 2021). Lakes in high latitude and altitude areas generally have a simple ecosystem structure and low biodiversity and are, therefore, extremely sensitive to anthropogenic perturbations and climate changes (Smol et al., 2005;Lin et al., 2017). Although these areas generally are less anthropogenically impacted, the air temperature has increased substantially over the past several decades (GISTEMP-Team, 2019), which may lead to increased water temperatures, decreased ice cover and longer growing seasons for aquatic organisms (Rouse et al., 1997;Smol et al., 2005). ...
Article
Glacier retreat in high altitude areas triggered by anthropogenic warming exerts a profound impact on the ecology of glacier-fed lakes. In this paper, we report on the results of a multi-proxy analysis of a Lateglacial (13.3–11.3 cal kyr B·P.) core obtained from the glacier-fed Kanas Lake in the Altai Mountains, China, to understand the responses of aquatic ecosystems to meltwater influxes. Core intervals with high sand fractions and enriched silicon dioxide and zirconium (~11.5, 11.7, 11.8, 12.2 and 13.0 cal kyrs B·P.) reflect intense meltwater pulses from alpine glaciers. In the core, these pulses generally coincide with low abundance of littoral cladocerans, high abundance of planktonic Pediastrum, and high phosphorus concentrations. Our results suggest that intense meltwater influxes not only brought nutrients (nitrogen and phosphorus) into the lake and promoted phytoplankton growth, they also generated cold, turbid water masses and restricted the growth of benthic algae and invertebrates. Therefore, we infer that future anthropogenic warming may lead to significant changes in the structure and function of aquatic ecosystems in glacier-fed lakes worldwide.
... Снижение численности и биомассы организмов отдельных звеньев трофической сети, а также их элиминация приводят к изменениям структурно-функциональных параметров водных экосистем и нарушениям взаимосвязей между гидробионтами различных трофических уровней [58][59][60][61][62]. Функционирование высших трофических уровней и перенос веществ и энергии в водных экосистемах определяются развитием первичного звена пищевых сетей -водорослей, одного из основных продуцентов органического вещества. ...
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Проанализированы данные мониторинговых исследований (2014-2016 гг.) состояния гидробионтов в водотоках при обустройстве месторождения углеводородов на полуострове Ямал. Показано, что наибольшее влияние на гидробионтов оказывает повышенное содержание взвешенных веществ. При фоновых значениях 4-6 мг/л концентрация взвешенных веществ в зоне попадания в водотоки стоков с карьеров достигает 440 мг/л и выше. Влияние повышенной мутности на качествен-ные и количественные показатели планктонных организмов не установлено. Увеличение содержа-ния взвешенных веществ в воде оказывает негативное влияние на зообентос (для числа видов r Sp = =-0.426, p = 0.030; для численности r Sp =-0.590, p = 0.002; для биомассы r Sp =-0.480, p = 0.013) и рыб (для экологической плотности мелких видов рыб r Sp =-0.567, p = 0.004). Особо чувствительны к повышенному содержанию взвешенных веществ сиговые рыбы, из карповых-озерный гольян. Наиболее толерантны к мутности девятииглая колюшка и сибирский голец-усач. Повышенные концентрации взвешенных веществ в осенний период-причина прекращения подъемной миграции сиговых рыб из Обской губы в глубокие верховые озера.
... We also did not include sediment, which can mediate water chemistry (McGowan et al. 2020). Finally, our simplified food webs did not include planktivorous fish, which can dramatically impact zooplankton responses to increasing salinity (Lin et al. 2017). Research investigating responses to salinization under various environmental contexts is warranted (Cunillera-Montcusí et al. 2022). ...
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Across the Northern hemisphere, chloride concentrations in lakes are increasing from decades of road salt use, threatening aquatic ecosystems. Zooplankton are sensitive to increasing chloride but few studies have considered how additional stressors, such as soft water or increasing lake temperatures interact with the negative effects of chloride. To determine the effects of increasing chloride and temperature on freshwater zooplankton and phytoplankton communities, we conducted a mesocosm experiment using 30 concentrations of chloride from ambient levels to 1500 mg L−1, ambient or warmed (+2.7°C) temperatures, and plankton from a softwater lake. We compared the results with current Canadian Water Quality Guidelines (CWQG) for chronic exposure to chloride. Although warming elicited little response, increasing chloride concentrations led to reduced zooplankton biomass and richness, even at concentrations below the CWQG, and an increase in cyanobacteria abundance, suggesting that policies regulating road salt application should be reevaluated to better protect aquatic ecosystems.
... TDS). These lakes are located at a distance of ~200 km (north-western direction) and ~100 km (north-eastern direction) to Shen Co and are also dominated by the chironomid morphotypes Procladius and P. sordidellus-type (Zhang et al., 2007;Lin et al., 2017). ...
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Understanding climate and monsoonal dynamics on the Tibetan Plateau is crucial, as recent hydrological changes, evidenced by rising lake levels, will be accelerated by current global warming and may alter aquatic habitats and species inventories. This study combines chironomid assemblages with sedimentological, mineralogical and geochemical data of a short sediment core (37.5 cm) from the high-altitude (> 4,733 m asl), saline (9 g L-1) and shallow (~5 m water depth) Shen Co, located in the southern part of the central Tibetan Plateau. The predominantly littoral, species-poor (10 chironomid morphotypes) chironomid assemblages are dominated by salt-tolerant taxa, that are highly sensitive to lake level fluctuations and macrophyte vegetation dynamics, making them ideally suited for tracking lake level changes over time. Results indicate a period (from ca. 1830 to 1921 CE) of drier conditions with low runoff and high evaporation rates in the Shen Co catchment, as indicated by a dominance of low-Mg calcite and dolomite and increased Ca/Fe and Sr/Rb ratios. This resulted in a decline in lake levels, an increase in salinity and the periodic occurrence of desiccation events at the sampling site. The first chironomid morphotype to appear after the dry period is Acricotopus indet. morphotype incurvatus, which indicate still low (
... The Tibetan Plateau is one of the most sensitive areas to global climate change. Since 1960, precipitation has risen by 12%, and temperatures have increased by 0.4°C per decade, which is three times the global average (Lin et al., 2017). This has led to glacier retreat and degradation of permafrost (Yao et al., 2012;Cheng and Jin, 2013). ...
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High-resolution multi-proxy records from two lakes on the southern Tibetan Plateau, Nam Co and Tangra Yumco, are used to infer long-term variations in the Asian monsoon system with a novel set of ostracod shell chemistry proxies. We track the moisture evolution since the Last Glacial Maximum using the trace element, rare earth element (REE) and stable isotope composition of ostracod shells. The sediment records covering the past 18.8 cal. ka BP and 17.4 cal. ka BP, respectively, demonstrate the suitability of REEs as indicators of weathering intensity and thus hydrological changes and moisture sources in the catchment. In Nam Co, high concentrations of light REEs between 14 to 13 cal. ka BP suggest an increased drainage from the glaciated Nyainqêngtanglha Mountains in the south, pointing to meltwater input. REEs in ostracod shells therefore provide additional information on water sources critical for the interpretation of stable isotope records. Mg/Ca, Sr/Ca and Ba/Ca ratios reflect salinity and thus changes in effective moisture. Asynchronous behavior of Mg/Ca, Sr/Ca and Ba/Ca ratios are controlled by changes in dominance of precipitating carbonate minerals in the lake. Synchronous behavior reflects calcite precipitation, indicating low-Mg/Ca warm-wet conditions. Constantly low Sr/Ca ratios reflect aragonite precipitation, indicating high-Mg dry conditions. Increased Sr/Ca and Ba/Ca relative to Mg/Ca ratios show monohydrocalcite precipitation, indicating high-Mg/Ca cold-dry conditions. Furthermore, Fe/Ca, Mn/Ca and U/Ca ratios in ostracods reflect changes in oxygen saturation in lake bottom waters controlled by lake level and microbial activity. The paleoclimate histories reconstructed from Nam Co and Tangra Yumco show high similarity throughout the late Quaternary. We identified two major dry periods, corresponding to Heinrich 1 and the Younger Dryas, followed by strengthening in Indian summer monsoon precipitation. The early Holocene is characterized by a moisture maximum, reflecting abundant water supply by a strong ISM. A time-delayed shift to dry conditions occurred at 2.6 cal. ka BP at Tangra Yumco, and at 2 cal. ka BP at Nam Co, resulting in decreasing lake levels, caused by weakened monsoon intensity due to a southeastward migration of the ISM-Westerly boundary with an estimated velocity of approximately 600 m per year.
... In Northwest China, temperatures have risen markedly in recent decades and faster than in the surrounding regions (Shi et al., 2007;Yang et al., 2020). Climate change can influence lakes either through higher temperatures or by changes in salinity (Mosley, 2015;Greaver et al., 2016), the latter is particularly influential in arid and semiarid lakes (Brucet et al., 2012;Lin et al., 2017). Climate change is affecting the hydrological cycle with more frequent and intense precipitation, altered snow accumulation and melt, and changes in evaporation (Sorg et al., 2012;Zhou et al., 2015), leading to large-scale changes in lake salinity (Jeppesen et al., 2015;Rusuli et al., 2015). ...
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Endorheic lakes in arid regions of Northwest China are generally vulnerable and sensitive to accelerated climate change and extensive human activities. Therefore, a better understanding of the self-purification capacity of ecosystems, such as denitrification, is necessary to effectively protect these water resources. In the present study, we measured unamended and amended denitrification rates of Lake Bosten by adding the ambient and extra nitrate isotopes in slurry incubations. Meanwhile, we investigated the abundances and community structure of nitrous oxide-reducing microorganisms using qPCR and high-throughput sequencing, respectively, in the surface sediments of Lake Bosten to study denitrification potential in endorheic lakes of arid regions as well as the response of those denitrifiers to climatically induced changes in lake environments. Amended denitrification rates increased by one order of magnitude compared to unamended rates in Lake Bosten. The great discrepancy between unamended and amended rates was attributed to low nitrate availability, indicating that Lake Bosten is not operating at maximum capacity of denitrification. Salinity shaped the spatial heterogeneity of denitrification potential through changes in the abundances and species diversity of denitrifiers. Climate change had a positive effect on the water quality of Lake Bosten so far, through increased runoff, decreased salinity, and enhanced denitrification. But the long-term trajectories of water quality are difficult to predict alongside future glacier shrinkage and decreased snow cover.
... The rapid development of anthropogenic interventions including sanitary waste-water discharge and raw sewage input have been found to influence water quality, leading to eutrophication of the lake (Liang et al., 2021). Surveys from 2012 to 2015 indicate the concentration of total nitrogen (TN) in this lake is about 1.32 mg/L and the total phosphorus (TP) concentration is about 0.112 mg/L (Chen et al., 2016;Lin et al., 2017). ...
Article
Over the past decades, the Tibetan Plateau has been experiencing rapid climate change and increasing anthropogenic disturbance. The existing multi-proxy sediment records highlight the complex interplay of physical and ecological changes as a response to past climate changes on the Tibetan Plateau. Yet, it remains an open question of how sedimentary microbial communities respond to past climate changes and anthropogenic interventions. Using high-throughput Illumina sequencing, this study investigated the temporal changes of prokaryotic and eukaryotic communities in a Tibetan lake sediment core spanning the last 600 years. There were obvious temporal distributions of prokaryotic and eukaryotic indicator taxa, and these temporal patterns were mainly influenced by mean annual temperature (MAT), total phosphorus (TP) and nitrogen:phosphorus ratio (N:P). The alpha diversity of eukaryotic communities significantly increased with time (P < 0.001), while the alpha diversity of prokaryotic communities did not exhibit obvious temporal turnover. Both prokaryotic and eukaryotic communities exhibited significant temporal-decay relationships. However, the turnover rate of the temporal-decay of eukaryotes (0.119) was significantly higher than that of prokaryotes (0.092). The effect of TP and N:P on the prokaryotic and eukaryotic communities were higher than that of MAT. The insights gained from this study can be helpful to understand the effects of past climate change and anthropogenic activities on the temporal distribution patterns of microbial communities, thus providing insights into predicting the succession of microbial communities and underlying mechanisms that drive them under future climate scenarios.
... In addition, the connectivity of both zooplanktonic and phytoplanktonic nodes was significantly associated with low salinities. This observation could be due to the salinity increase not only could significantly decreased the zooplanktonic and phytoplanktonic diversity, but short the oceanic food chain (Brucet et al., 2009;Lin et al., 2017;Mo et al., 2021). ...
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Although autotrophic phytoplankton and heterotrophic zooplankton both play important roles in the food web of marine ecosystem, their comprehensive interactions and spatial patterns at continental scale remain poorly studied. Here, we collected 251 seawater samples along 13,000 km of Chinese coastline, and microscopically investigated the latitudinal gradients of planktonic diversities. In total, 307 phytoplanktonic and 311 zooplanktonic species were visually identified. Using the newly developed Inter-Domain Ecological Network (IDEN) approach, the phytoplankton-zooplankton interaction networks were constructed. We found that the phyto-zooplankton network structure was varied across three regions, more complex and numerous connections along the southern coast than in the north. In addition, some particular associations between zooplanktonic and phytoplanktonic groups were found to be localized in specific regions. For example, autotrophic Chaetoceros lorenzianus was only associated with heterotrophic Copepoda in the northern regions. Furthermore, and the seawater temperature and salinity were the major driving force for shaping planktonic interaction networks. These results provide a deeper understanding of planktonic biogeography and phytoplankton-zooplankton interaction patterns.
... The factors elaborated above are imperative to phytoplankton, especially for phytoplankton of the alpine lakes in the Tibetan Plateau. The lakes in the Tibetan Plateau experience a warm and wet climate [55,56], leading to changes in the water temperature, nutrients, and salinity and eventually facilitating the growth of phytoplankton [57]. Particularly, phytoplankton blooms may occur in those brackish lakes with enough nutrients under climate change. ...
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In this paper, two trophic lakes: Lake Taihu and Lake Yanghe, and three alpine lakes: Lake Qinghai, Lake Keluke, and Lake Tuosu, were investigated to discover the connections between environmental factors and the phytoplankton community in lakes with differences in trophic levels and climatic conditions. Three seasonal data, including water quality and phytoplankton, were collected from the five lakes. The results demonstrated clear differences in water parameters and phytoplankton compositions in different lakes. The phytoplankton was dominated by Bacillariophyta, followed by Cyanobacteria and Chlorophyta in Lake Qinghai, Lake Keluke, and Lake Tuosu. It was dominated by Cyanobacteria (followed by Chlorophyta and Bacillariophyta in Lake Yanghe) and Cyanobacteria (followed by Chlorophyta and Cryptophyta in Lake Taihu). The temperature was an essential factor favoring the growth of Cyanobacteria, Chlorophyta, and Bacillariophyta, especially Cyanobacteria and Chlorophyta. The pH had significantly negative relationships with Cyanobacteria, Chlorophyta, and Bacillariophyta. Particularly, a high pH might be a strong and negative factor for phytoplankton growth in alpine lakes. A high salinity was also an adverse factor for phytoplankton. Those results could provide fundamental information about the phytoplankton community and their correlated factors in the alpine lakes of the Tibetan Plateau, contributing to the protection and management of alpine lakes.
... With salinity increased, biodiversity declined exponentially. Lin et al. (2017) invested zooplankton communities in 45 lakes of the Tibetan Plateau and found that species richness declined significantly with salinity. In addition, our unpublished data of benthic macroinvertebrates in 40 lakes of the Tibetan Plateau showed that the taxa composition in saline lakes was significantly different from that in freshwater lakes. ...
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Biodiversity patterns along the elevational gradient of vertebrates have been widely focused on in previous studies, but they are still insufficient on invertebrates in lakes to a wide elevational extent. Based on field samplings and literature, we compared biodiversity patterns among different taxonomic groups of benthic macroinvertebrates in 104 lakes of China and India along an elevational gradient of 2–5,010 m a.s.l. and revealed the key driving factors, and then, we discussed the key mechanisms underlying elevational biodiversity patterns. We found that elevational biodiversity patterns of different taxonomic groups were not uniform, e.g., an exponentially decreasing pattern of Bivalvia, a first horizontal and then decreasing pattern of Gastropoda, and a linear decreasing pattern of Oligochaeta and Insecta. Elevation and elevation-controlled variables (temperature and salinity) were the key driving factors to biodiversity patterns. Their effects were strongest on Bivalvia and less on Gastropoda, whereas they were relatively weak on Oligochaeta and Insecta. Finally, we discussed three important mechanisms that shaped elevational biodiversity patterns and assemblage variations of benthic macroinvertebrates by linking our results with the classic hypotheses about biodiversity patterns, including climate/productivity, environmental heterogeneity, and dispersal/history. These results could improve our understanding of biodiversity patterns and biodiversity conservation.
... The Tibetan Plateau features the largest number of lakes in China (> 1500 lakes); most of these are salt lakes [32], and more than 97% as inland lakes [33]. Lakes play a key role in the hydrological cycle in Tibet and greatly affect the regional climate, water resources, and terrestrial/aquatic ecosystems [34]. ...
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Background Lake is a critical part of Tibet's hydrological cycle, the lake–terrestrial ecotone is the most sensitive area in the water and terrestrial ecosystem. For the ecological protection and maintenance of the lakeside zone, defining the upper boundary of the lake–terrestrial ecotone is a key issue that needs to be solved urgently. However, the ecological characteristics of lake–terrestrial ecotone made it difficult to delimit. Wetland herbs are characteristic plants of the lake–terrestrial ecotone, and their distribution width can be used to reflect the upper boundary of the lake–terrestrial ecotone. We took Baksum Lake, Yamdroktso, Namtso, Siling Co as examples, based on the spatial structure of the lake–terrestrial ecotone, used the moving split-window technology (MSWT) delimited the width of wetland herbs. Results The results of the MSWT showed the distribution width of wetland herbs in each lake–terrestrial ecotone with the natural-wetland type sampling line of Baksum Lake, Yamdroktso, Namtso, Siling Co was 51 m, 56 m, 33 ~ 53 m, 19 ~ 31 m. The detrended correspondence analysis (DCA) showed quantity of wetland herbs species, BK1 > YT1 = NT1 > NT2 > SC1 = SC2. The principal component analysis (PCA) and the (redundancy analysis) RDA showed soil moisture content (SMO), pH, soil moisture content (SSC), and soil nutrient content had obvious correlation with distribution width. Conclusion The MSWT was a feasible method to determine the width of lake – terrestrial ecotone. SMO, pH, SSC, and soil nutrient content were all important environmental factors affecting the wetland herbs distribution width of the four lakes; and the SMO was the most important factor. Besides, compared with the lakes in the Middle-Lower Yangtze Plain, the high-density population distribution, high-intensive human activity invaded the plants' growth area, resulting in a smaller distribution width. The distribution edge of wetland herbs is equivalent to the upper boundary of lake–terrestrial ecotone. It determines the management boundary of the lake–terrestrial ecotone, provides a theoretical basis for the construction of environmental protection projects, and is of great significance to the lake ecological restoration and management in watershed control planning.
... This result is consistent with studies reporting relatively high salt tolerance in rotifers (Schallenberg et al. 2003). However, in contrast to our expectation, the decrease in crustacean abundance and, therefore, competition for phytoplankton, was not accompanied by an increase in rotifer abundance, as observed elsewhere (Jeppesen et al. 2007;Van Meter and Swan 2014;Lin et al. 2017). Furthermore, the parallel study by Hintz et al. ...
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Human-induced salinization increasingly threatens inland waters; yet we know little about the multifaceted response of lake communities to salt contamination. By conducting a coordinated mesocosm experiment of lake salinization across 16 sites in North America and Europe, we quantified the response of zooplankton abundance and (taxonomic and functional) community structure to a broad gradient of environmentally relevant chloride concentrations, ranging from 4 to ca. 1400 mg Cl/L. We found that crustaceans were distinctly more sensitive to elevated chloride than rotifers; yet, rotifers did not show compensatory abundance increases in response to crustacean declines. For crustaceans, our among-site comparisons indicate: (1) highly consistent decreases in abundance and taxon richness with salinity; (2) widespread chloride sensitivity across major taxonomic groups (Cladocera, Cyclopoida, and Calanoida); and (3) weaker loss of functional than taxonomic diversity. Overall, our study demonstrates that aggregate properties of zooplankton communities can be adversely affected at chloride concentrations relevant to anthropogenic salinization in lakes.
Article
Despite significant climate change on the Tibetan Plateau, the historical succession trend and underlying driving mechanism of aquatic ecosystem in alpine lake remain unclear. In this study, palaeolimnological analysis and high-throughput sequencing of sedimentary DNA were used to investigate environmental changes, primary productivity, and eukaryotic algal community succession over the past millennium in Lake Yamzhog Yumco of the southern Tibetan Plateau. Lake primary productivity significantly increased after ~1850 CE and algal community succession occurred in three stages including the Medieval Warm Periods (approximately 1000–1250 CE), the Little Ice Age (1250–1850 CE), and the Current Warm Period (1850–2020 CE). Moreover, succession was synchronous with inferred climate changes. Partial least square path modeling indicated that climate factors affected primary productivity and eukaryotic algal community structure by affecting nutrient loading. The results suggest that glacier melting and permafrost degradation caused by climate warming, combined with increased precipitation, may be the major driving factors of nutrient concentration increases, phytoplankton biomass increases, and shifts in community composition. Considering the expected trends of future climate change and continuous warming, the restoration of vegetation cover and reduction of non-point source nutrient loading in the Tibetan Plateau is urgently needed to mitigate climate change impacts on alpine lake aquatic ecosystems.
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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 g/l) to the dominance of large daphnia (3-8 g/l), copepods (> 8 g/l), small cladocerans and rotifers (20-30 g/l), and Artemia (> 30 g/l). The top predator (fish) was eliminated at salinity above 10 g/l. The biomass of zooplankton did not depend on salinity, but significantly increased in lakes with an increased nutrient load. The nutrient load also had a significant effect on the concentration of total phosphorus, turbidity and transparency of water, and the concentration of chlorophyll “a”. Thus, we recorded the structuring effect of the nutrient load (bottom-up control) on the biomass of the trophic levels and the parameters of water transparency, while salinity transformed the trophic chain from the top, leading to the disappearance of fish and a change in the dominant species of zooplankton. At the same time, salinity did not affect the biomass of the trophic levels. In order to detect top-down effects in the ecosystems of saline lakes, it is necessary to perform a comparative analysis of the seasonal dynamics of ecosystems of lakes with different salinity.
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• The American brine shrimp Artemia franciscana is important in aquaculture and has become invasive in other continents, aided by dispersal via waterbirds. However, little is known about processes underlying its genetic diversity and population structure in its natural habitat in North America. These processes, including dispersal and local adaptation, are pivotal drivers of species distribution and community structure, and therefore central to aquatic biodiversity. • We studied 15 populations in natural saline lakes of Saskatchewan, Canada to determine the influence of variation in geological history, water chemistry, lake size, and location. We aimed to determine the relative importance of isolation by distance and isolation by environment using the cytochrome c oxidase subunit 1 gene (CO1) as a mitochondrial marker and five nuclear microsatellite markers. • Geographic patterns for CO1 and microsatellites differed, with lakes clustering in different groups based on genetic distances according to the marker used. CO1 better indicated historical colonisation processes, suggesting potential routes of initial colonisation when lakes were formed after deglaciation 11,000–15,000 years ago. • Differentiation between lakes based on nuclear markers was strongly related to variation in hydrochemistry, suggested by distance-based redundancy analysis, but there was no indication of isolation by distance. The ratio between alkalinity and the sum of Ca and Mg concentrations was particularly important, although a lake with a high Cl concentration caused by potash mining also had a unique Artemia population. • Geochemistry is important in the adaptive radiation of anostracan crustaceans. Our study suggests that it also underlies intraspecific genetic variation between populations, promoting isolation by environment, and making dispersal ineffective when cysts are moved by birds between lakes with different hydrochemistry.
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In nowadays, world trade and cargo transportation mainly rely on shipping, and inland ports provide valuable and essential services to the maritime transport. With the increase of trade volume, the discharge of ballast water from ships is also increasing, which brings in ecological challenges. The International Maritime Organization stipulates that the number of organisms in discharged ballast water should be limited to prevent biological invasion to recipient waters. However, ballast water still contains many substances of source water, and may affect the plankton community in the recipient waters. In this study, the effects of ballast water on nature freshwater plankton community were evaluated at laboratory scale. It was observed that the abundance and diversity of planktons decreased with increase of water salinity. Through 10 days of continuous monitoring, it was found that ≥ 50 µm organisms were more sensitive to rising salinity than 10–50 um organisms, when water salinity was not over 3.6‰, there was no significant difference on ≥ 50 µm organisms quantity and diversity compared with the freshwater control group after 10 days, and the biota maintained certain recovery ability, while 10–50 um organisms had recovery ability when water salinity was not over 6.5‰. However, when the water salinity was over 6.5‰, both species composition and organism density showed irreversible and rapid reduction. In addition, organism species Platyias sp., Polyarthra sp., Tribonema sp., Navicula sp. were found to be very sensitive to salinity change and could be considered as indicative organisms for monitoring and evaluating ecological effect of discharge of saline ballast water. This is of great significance for the scientific management of ballast water discharge in fresh waters in the future.
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Eukaryotes exist widely in aquatic ecosystems. It is of great importance to study their species composition, diversity, and relationship with environmental factors to protect and maintain ecosystem balance. Salt lakes are essential lakes rich in biological and mineral resources and have significant research value. To understand the characteristics of eukaryotic diversity in salt lake sediments, we conducted a sampling survey of the benthos in Kyêbxang Co, Tibet, in July and August 2020. The sampling area was divided into littoral, sublittoral, and profundal zones. A total of 42 species of Metazoa, 159 species of Protozoa, 63 species of Viridiplantae, and 46 species of Fungi were identified by the high-throughput sequencing of 18S ribosomes. Alpha diversity analysis revealed significant differences in species composition among the three study zones. The littoral zone had the highest Sobs index and Chao index, indicating that the eukaryotic diversity and richness in this zone were significantly higher than those in the profundal and sublittoral zones. Redundancy analysis (RDA) showed that water depth, temperature, and sediment organic matter content significantly affected the community structure of eukaryotes zones, especially the distribution of dominant genera such as Dunaliella, Psilotricha and Brachionus. Cooccurrence network analysis showed that Dunaliella, Aphelidium, temperature, water depth, and organic matter represent essential nodes in the entire network. This study can provide baseline data and new insights for eukaryotic diversity research for salt lakes.
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Qinghai-Tibet Plateau (QTP) Lake Region has largest abundance and size distribution of lakes in China. Being relatively away from major human activities, the water quality of these lakes has not attracted concerns in the past. However, dramatic climate change and intensified anthropogenic activities over the past 30 years have exerted multiple pressures on the water environment of the lakes, resulting in elevated nutrient concentrations in major freshwater lakes of the region. Rapid water quality deterioration and eutrophication of the lakes were first found in Lake Hurleg in the northeast of the plateau. Analyses of driving forces associated with these changes indicate that both the intrinsic characteristics of the QTP lakes and climate change were responsible for the vulnerability to human activities than other lakes in different regions of China, with accelerated urbanization and extensive economic development in the lake basin playing a decisive role in creating water pollution events. Under combination pressures from both natural and anthropogenic effect, the increasing rate of nutrient concentrations in Lake Hurleg has been 53–346 times faster than in Lake Taihu and Lake Dianchi during the deterioration stage. The result suggests the current development mode of Lake Hurleg basin is not suitable for setting protection targets for the QTP lake region more broadly due to its extremely poor environmental carrying capacity. To stop worsening the lake water environment condition, it is necessary to review the achievements made and lessons learned from China’s fight against lake pollution and take immediate measures, inform policies into the development mode in the QTP lake region, and avoid irreversible consequences and ensure good water quality in the "Asian Water Tower."
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Anthropogenic and natural disturbance to inland aquatic ecosystems displays a notable spatial difference, yet data to measure these differences are scarce. This study encompasses 217 lakes distributed over five lake regions of China and elucidates the environmental factors determining the spatial variability of the water quality and trophic status. A significant correlation between human modification index in surrounding terrestrial systems (HMT) and trophic status of lake ecosystems (TSI) was found, and the regression slope in each region was similar except in the Qinghai-Tibet Plateau region. It was further noted that the pattern of environmental factor network (EF network) differed among freshwater and saline lakes. The EF network was complex for freshwater lakes in less human-influenced areas, but intensive man-made influence disrupted most relationships except for those between total nitrogen, total phosphorus, chlorophyll- a , and water turbidity. As for regions including saline lakes, correlations among water salinity and organic forms of carbon and nitrogen were apparent. Our results suggest that HMT and EF network can be useful indicators of the ecological integrity of local lake ecosystems, and integrating spatial information on a large scale provides conservation planners the option for evaluating the potential risk on inland aquatic systems.
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