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Our study focused on freshwater fungal diversity, an important aspect in assessing the ecology of aquatic ecosystems. We carefully explored the diversity and influencing factors of culturable fungi across Dianchi Lake, Fuxian Lake, Xingyun Lake, and Yangzonghai Lake in Yunnan Province, China. Through fungi culture, morphological characterization, and ITS sequence analysis, we identified a total of 565 isolates belonging to 405 species across 133 genera. The diversity indices viz. H′, D, and J were evaluated for fungal diversity across the lakes. Interestingly, although diversity indices were highest during summer and at Yangzonghai Lake, no significant differences in fungal community diversity were observed between seasons and regions. Water variables were analyzed and indicated that changes with rapid fluctuations in temperature, pH, and dissolved oxygen likely influence fungal diversity. These findings significantly contribute to our understanding of fungal communities within plateau lake ecosystems, thereby aiding in managing and conserving vital aquatic resources. [ABSTRACT FROM AUTHOR]

Accurate determination of reaeration coefficient in lakes is a key factor for accurate modeling of dissolved oxygen. This study developed a new numerical model to determine the lake reaeration coefficient of Sawa lake, Iraq based on solving the transform mechanisms of dissolved oxygen without the using the empirical and laboratory methods. The model solved the gas transport at the water-air surface numerically to predict the dissolved oxygen and the reaeration coefficient simultaneously. Results showed that the lake reaeration coefficient was 0.001 day-1 at 20 °C with low root mean squared errors (0.138, 0.137, and 0.168 mg/L for the three years of simulation 2007, 2012, and 2017, respectively) and absolute mean errors (0.121, 0.114, and 0.145 mg/L in 2007, 2012, and 2017, respectively). It was noticed that the lake habitat was impacted causing unhealthy conditions (low reaeration rate), and there was upward dissolved oxygen movement due to the presence of positive trend in the yearly cycle of temperature. In addition, including this numerical approach along with other water quality models can improve the predictions of other water quality parameters. [ABSTRACT FROM AUTHOR]

IntroductionAccurate models of lake primary production are crucial for understanding ecosystem function and predicting ecosystem responses to global change. However, current research in lake ecosystem modeling has emphasized environmental characteristics while less work has considered phytoplankton stoichiometric traits. Importantly, these traits link resource availability to primary production via organismal metabolism and thus are critical to predicting ecosystem function.MethodsHere, we use an existing database of phytoplankton traits and lake ecosystem models to demonstrate that phytoplankton minimum quotas for nitrogen and phosphorus significantly influence predictions of lake gross primary production. Additionally, we compare how different parameterizations of phytoplankton stoichiometry affect modeled gross primary production. Finally, we evaluate the ability of the models to capture observed patterns in gross primary production and seston stoichiometry for lakes in the Northern Hemisphere.Results and discussionWe argue that parameterization and calibration of phytoplankton stoichiometric traits will improve lake ecosystem models and are critical for obtaining better estimates of lake primary production.

Lake sediment records are of great importance for understanding the evolution of watershed environments. Various studies have been carried out to determine the depositional ages of lake sediments and to examine their physical, chemical, and biological characteristics. The aim is to construct the historical vegetation, environment, and climate patterns in Chinese lake watersheds. In this review, we obtained relevant studies on lake sediment records by searching the key word 'age-depth' from the following databases: Web of Science and the China National Knowledge Infrastructure (CNKI, the largest Chinese academic database). We analyzed the literature based on its type (published in a Chinese/English journal or as a Master's/PhD thesis), period of publication, journal (if published in a journal), key authors, study area, dating scale, and main aims. The results suggest that the lakes in the plateau regions are the most popular research topic, typically covering 100–200 years (short-term) and 500–30,000 years (long-term). The literature focuses on a wide range of topics, from past environmental evolution in watersheds to lake ecology, and it provides a solid foundation for a better understanding of the regional climate change and the preservation of lake environments and ecosystems. In the future, the resulting data obtained from environmental reconstructions with lake sediments will need to be integrated with emerging information processing technologies (e.g., artificial intelligence and meta-analysis) to disentangle the complex interplay between the Earth's surface processes and global climate change; furthermore, strengthening interdisciplinary collaboration will deepen our comprehension of the man-land relationship and promote the sustainable management of lake ecosystems in the context of global climate change. [ABSTRACT FROM AUTHOR]

Our study focused on freshwater fungal diversity, an important aspect in assessing the ecology of aquatic ecosystems. We carefully explored the diversity and influencing factors of culturable fungi across Dianchi Lake, Fuxian Lake, Xingyun Lake, and Yangzonghai Lake in Yunnan Province, China. Through fungi culture, morphological characterization, and ITS sequence analysis, we identified a total of 565 isolates belonging to 405 species across 133 genera. The diversity indices viz. H′, D, and J were evaluated for fungal diversity across the lakes. Interestingly, although diversity indices were highest during summer and at Yangzonghai Lake, no significant differences in fungal community diversity were observed between seasons and regions. Water variables were analyzed and indicated that changes with rapid fluctuations in temperature, pH, and dissolved oxygen likely influence fungal diversity. These findings significantly contribute to our understanding of fungal communities within plateau lake ecosystems, thereby aiding in managing and conserving vital aquatic resources.

Organic carbon decomposition in lake sediments contributes substantially to the global carbon cycle and is strongly affected by temperature. However, the magnitude of temperature sensitivity (Q10) of decomposition and the underlying factors remain unclear at the continental scale. Carbon quality temperature (CQT) hypothesis asserts that less reactive and more recalcitrant molecules tend to have higher temperature sensitivities, but its support is challenged by complex composition of organic matter and environmental constraints. Here, we quantified Q10 of the sediments across 50 freshwater ecosystems along a 3500 km north–south transect, and characterized the quality of sediment dissolved organic carbon with chemodiversity reflected in molecular richness, functional traits (i.e., molecular weight, bioavailability, etc.) and composition. We further included classic environmental variables, such as climatic, physicochemical and microbial factors, to explore how Q10 is constrained by these factors or carbon quality. We found that Q10 varied greatly across lakes, with the mean value of 1.78 ± 0.62, but showed nonsignificant latitudinal pattern. Q10 was primarily predicted by chemodiversity and showed an increasing trend with the biochemical recalcitrance indicated by traits such as aromaticity and standard Gibb's Free Energy at both molecular and compositional levels. This suggests that carbon quality is the crucial determinant of Q10 in lakes, supporting the CQT hypothesis. Moreover, Q10 decreased linearly with the increase of molecular richness, implying that the resistance of decomposition to warming is associated with higher molecular diversity. Compared with the structural equation model containing only environmental variables, inclusion of chemodiversity increased 32.8% of the explained variation in Q10, and chemodiversity was the only driver showing direct effects. Collectively, this study illustrates the importance of chemodiversity in shaping the pattern of Q10, and has significant implications for accurately predicting the carbon turnover in lake ecosystems in the context of global warming. [ABSTRACT FROM AUTHOR]

Decreasing water volume and increasing pollutants in wetlands pose challenges to aquatic life. While environmental flow regulation is widely applied to enhance aquatic habitats, its effectiveness needs to be evaluated. In this study, a hydrodynamic-water quality model was used to simulate the fields of flow, temperature, and pollutants. The Ecological Niche Modeling at the MetaLand EcologyLab (ENMTML) was utilized to evaluate the area of suitable habitats for aquatic organisms under both environmental flow regulation and no environmental flow regulation conditions. The typical Baiyangdian Wetland in northern China was taken as the study area, and the important economic fish, Cyprinus carpio, served as the indicator of aquatic species. The effectiveness of environmental flow regulation was evaluated from December 1, 2017, to June 30, 2018. The results indicated that the variables of water depth, dissolved oxygen (DO), ammonia nitrogen (NH4+-N) and Chlorophyll a (Chla) were the major environmental factors determining the variability of the suitable habitat area for Cyprinus carpio. The environmental flow regulation capacity of the Baiyangdian Wetland was 2.6 × 108 m3, which produced a suitable habitat area of 135.538 km2 at the end of the water supply period. Compared with the no environmental flow regulation condition, the highly and moderately suitable habitat areas for Cyprinus carpio were enlarged by 56.30 km2 and 34.11 km2, respectively. The outcome provides not only a basic reference for wetland management, but also a scientific perspective for understanding the impact of environmental flow regulation on aquatic organisms. The proposed method demonstrates the important potential of evaluating the effectiveness of environmental flow regulation on aquatic organisms in wetlands. [ABSTRACT FROM AUTHOR]

Lake sediment records are of great importance for understanding the evolution of watershed environments. Various studies have been carried out to determine the depositional ages of lake sediments and to examine their physical, chemical, and biological characteristics. The aim is to construct the historical vegetation, environment, and climate patterns in Chinese lake watersheds. In this review, we obtained relevant studies on lake sediment records by searching the key word ‘age-depth’ from the following databases: Web of Science and the China National Knowledge Infrastructure (CNKI, the largest Chinese academic database). We analyzed the literature based on its type (published in a Chinese/English journal or as a Master’s/PhD thesis), period of publication, journal (if published in a journal), key authors, study area, dating scale, and main aims. The results suggest that the lakes in the plateau regions are the most popular research topic, typically covering 100–200 years (short-term) and 500–30,000 years (long-term). The literature focuses on a wide range of topics, from past environmental evolution in watersheds to lake ecology, and it provides a solid foundation for a better understanding of the regional climate change and the preservation of lake environments and ecosystems. In the future, the resulting data obtained from environmental reconstructions with lake sediments will need to be integrated with emerging information processing technologies (e.g., artificial intelligence and meta-analysis) to disentangle the complex interplay between the Earth’s surface processes and global climate change; furthermore, strengthening interdisciplinary collaboration will deepen our comprehension of the man-land relationship and promote the sustainable management of lake ecosystems in the context of global climate change.

Downscaling Chlorophyll-a (Chl-a) concentration derived from satellite image is crucial for refined applications such as water quality monitoring. However, the precision of downscaling is usually constrained by various environmental factors. In this paper, we develop a downscaling method for Chl-a concentration to improve precision, especially for inland lakes with different surrounding environment. The method downscales the Sentinel-3 Chl-a concentration from 300 m to 30 m, based on the multivariate analysis (MVA) and the gradient boosting decision tree (GBDT) model. Firstly, we analyzed 21 Chl-a concentration related indices to identify optimal factors for Chl-a concentration variability. Secondly, a GBDT model is constructed to convey the non-linear relationship between the optimal factors and Chl-a concentration at coarse resolution. Finally, fine-resolution Chl-a concentrations were produced by employing the model to refine cofactors for 12 distinct lakes. The results indicated that the proposed MVA-GBDT method effectively inferred the variability of Chl-a concentration with a mean RMSE of 4.505 mg/m3, an improvement of 5%–39% over other methods. Furthermore, for lakes with large water quality heterogeneity, the method led to a cross validation RMSE and a difference in accuracy of 5.371 mg/m3 and 0.866 mg/m3, respectively. In addition, this study examined the significance of the auxiliary factors and found that the NDCI and WST were the two most important factors for MVA-GBDT to detect Chl-a concentration distributions, particularly for NDCI in lakes with high nutrient contrasts. These findings contribute to the generation of fine-scale Chl-a concentrations in lakes and support related applications.

Abstract The introduction of coarse woody habitat has been a widely adopted management practice for restoring and enhancing freshwater aquatic ecosystems. Although responses of aquatic fish and invertebrate communities have largely been documented for lotic systems, benefits for lentic ecosystems have been mostly unevaluated. We tested the responses of fish populations to coarse woody habitat structures through a Bayesian modelling approach in a northern boreal lake in Alberta, Canada by enhancing a stretch of littoral zone with low structural complexity through introduction of coarse wood bundles and whole tree structures. The study site was split into three treatments, a Spaced treatment (structures 30 m apart), a Clustered treatment (structures 15 m apart) and an unaltered area (Control). Catch per unit effort and catch per unit area data were collected over 2 years and posterior model predictions showed an increase in habitat use of the enhanced areas by spottail shiner—Notropis hudsonius; northern pike—Esox lucius; white sucker—Catostomus commersonii; brook stickleback—Culaea inconstans. No probable effect on overall fish condition, measured in Relative Weight, was linked to the enhancements. Across the 2‐year study, wood bundles degraded faster compared to the whole tree drops, coinciding with levelling off catch per unit effort and catch per unit area predictions near wood bundles, although catch predictions increased near the whole tree structures. Structural degradation set in as early as 1 week post‐construction for wood bundles and was mostly related to anchoring aspects. Results from our study provide evidence for the benefits provided by coarse woody habitat within northern boreal lake systems. They furthermore highlight the short‐lived nature of wood bundles built with biodegradable substances. Methodologically our results offer evidence on the feasibility and utility of predictive modelling frameworks in addressing pseudoreplication and providing informative value for ecological studies.

Sedimentary organic matter is an important component of the metabolism of a lake's ecosystem, and it is generally derived from both the watershed and the primary productivity of a lake. Understanding the sources of organic matter in lakes and lake trophic status is important when evaluating the quality of lake ecosystems. We summarize the spatial distribution of total nitrogen (TN), total organic carbon (TOC), TOC/TN (C/N) molar ratios, and organic carbon isotope (δ13Corg) of the surface sediments of Fuxian Lake, Yunnan–Guizhou Plateau, Southwest China, which is the second deepest freshwater oligotrophic lake in China. The results show that the distributions of TN, TOC, C/N, and δ13Corg of the surface sediments are spatially heterogeneous, which is also the case for the trophic conditions of the lake. Compared with the adjacent eutrophic lakes and typical lakes in other areas with strong human activities, the content of organic matter is at a low level. Meanwhile, the autochthonous organic carbon in the surface sediments was characterized by lower δ13Corg (−25.3~−28.5) and C/N (8.7~12.9), suggesting that the biological carbon pump effect plays a significant part in the stability of carbon sinks by coupling with carbonate weathering. Our results emphasize the importance of the carbon sink of coupled carbonate weathering and aquatic photosynthesis in the evolution of the carbon cycle in lakes. Although modern monitoring shows that Fuxian Lake is an oligotrophic lake, there are potential risks of organic nitrogen pollution with respect to surface sediments, especially in northern and southern shallow-water areas. The organic pollution of lakes can be reduced by controlling the discharge of wastewater and reducing the nutrient loading of agricultural runoff. [ABSTRACT FROM AUTHOR]

Freshwater bioindicators have been developed to assess ecosystem health and responses to human-induced stressors. To date, most bioindicators primarily rely on the species identity of plant and animal communities and do not account for interactions among organisms and fluxes of energy between trophic levels. Body size is one of the most important ecological traits in aquatic ecosystems because it governs interactions among organisms and is affected by environmental conditions but, surprisingly, many of assessment approaches do not use individual body size. The community size spectrum is defined as the linear relationship between the abundance and the body size of organisms and reflects several important ecological features including ecosystem carrying capacity, predation-prey interactions, and trophic energy fluxes. In this study, we explored the potential of using the size spectrum parameters (slope, elevation and linearity) of fish community as a complementary bioindicator in 51 natural lakes and 102 reservoirs distributed across France. We determined how the fish size spectrum and other common bioindicators based on fish, macrophyte and phytoplankton communities responded to the water quality degradation, littoral habitat alterations and fish invasions. Results demonstrated that: (i) the size spectrum was driven by water quality degradation both in lakes and reservoirs, while size spectrum was affected by habitat loss in natural lakes and by fish invasion in reservoirs and (ii) the size spectrum was more sensitive to habitat loss than common bioindicators in natural lakes. This study highlights that the use of fish community size spectrum could provide additional insights into our understanding of the responses of freshwater ecosystems to global changes and could serve to improve the efficiency of management programs. This can be done at very limited additional cost because fish body size is commonly measured in biomonitoring protocols.

Microbial communities in many ecosystems are facing a broad range of global change drivers, such as nutrient enrichment, chemical pollution, and temperature change. These drivers can cause changes in the abundance of taxa, the composition of communities, and the properties of ecosystems. While the influence of single drivers is already described in numerous studies, the effect and predictability of multiple drivers changing simultaneously is still poorly understood. In this study, we used 240 highly replicable oxic/anoxic aquatic lab microcosms and four drivers (fertilizer, glyphosate, metal pollution, antibiotics) in all possible combinations at three different temperatures (20, 24, and 28°C) to shed light into consequences of multiple drivers on different levels of organization, ranging from species abundance to community and ecosystem parameters. We found (i) that at all levels of ecological organization, combinations of drivers can change the biological consequence and direction of effect compared to single drivers, (ii) that effects of combinations are further modified by temperature, (iii) that a larger number of drivers occurring simultaneously is often quite closely related to their effect size, and (iv) that there is little evidence that any of these effects are associated with the level of ecological organization of the state variable. These findings suggest that, at least in this experimental ecosystem approximating a stratified aquatic ecosystem, there may be relatively little scope for predicting the effects of combinations of drivers from the effects of individual drivers, or by accounting for the level of ecological organization in question, though there may be some scope for prediction based on the number of drivers that are occurring simultaneous. A priority, though also a considerable challenge, is to extend such research to consider continuous variation in the magnitude of multiple drivers acting together. [ABSTRACT FROM AUTHOR]

Structural habitat enhancement has been long established as a popular tool to counter habitat loss due to land-use and development. One enhancement approach is the introduction of Coarse Woody Habitat (CWH) to improve the establishment of macrophyte, macroinvertebrate, and fish communities. Here we test for the effects of CWH in Northern boreal lakes in the context of mitigation projects. We constructed Coarse Woody Habitat structures in a structure-less littoral zone of Lake Steepbank within the Oil Sands Region of Alberta, Canada. Enhancement structures featured increased macrophyte and invertebrate richness and biomass compared to reference sites and pre-treatment assessments over three years. Enhanced sites also retained improved richness (macrophytes), diversity (macroinvertebrates), and biomass (both), despite STIN loss and degradation of enhancement structures over time. Using beta diversity components, constituting richness agreement, community differentiation, and site relationships, and testing their relative importance revealed that replacement was more dominant for invertebrates and increasing similarity more important for macrophyte communities post-enhancement. Our study shows the value of CWH addition for macroinvertebrate and macrophyte communities in what is otherwise a structure-less environment. Community changes over time showcase how beta diversity should be more strongly incorporated in restoration and enhancement studies to quantify community shifts that otherwise would not be captured in alternative diversity measures. [ABSTRACT FROM AUTHOR]

Since the second half of the 1970s, the ecosystems of lakes Batorino, Myastro, and Naroch have undergone anthropogenic eutrophication, targeted deeutrophication, and benthification caused by the introduction of the filter-feeding mollusk Dreissena polymorpha Pallas. The set of continuous series of seasonal mean values of eight parameters of each ecosystem obtained in 1978–2015 have been analyzed by mathematical-statistical methods of principal components (PCA) and singular spectra (SSA). The analysis showed that the complicated long-term dynamics of the set of the chosen parameters of the ecosystems was described during this period of time by three principal components by 92% and 90% for Lake Batorino and Lake Myastro, respectively, and by five principal components by 94% for Lake Naroch. We propose a biological interpretation of these principal components, i.e., a hypothesis of the factors exerting the greatest effect on the ecosystem dynamics during those years. The first main factor, which determines the dynamics of the ecosystems of lakes Batorino, Myastro, and Naroch by 63, 65, and 43%, respectively, is interpreted as the resistance of the lake ecosystem to a variable biogenic load, which is inversely related to the trophicity of the reservoir. The second main factor, which contributes 21, 15, and 22% to the dynamics of the ecosystem parameters of Naroch lakes (in the same order), was interpreted as solar radiation activity. The interpretation of the third main factor depends on the properties of a particular ecosystem. For ecosystems that are not deficient in biogenic elements (lakes Batorino and Myastro, with a contribution of the factor to the ecosystem dynamics of 8 and 10%), this may be the transfer of the primary organic matter to consumers of the next trophic level related to the structure of the food chain in the ecosystem. For an ecosystem in which the process of primary production formation is limited by the available amount of biogenic elements (Lake Naroch, in which the contribution of the third main factor to ecosystem dynamics is 13%), this very factor is the third main one, affecting the ecosystem long-term dynamics. The fourth main factor, which determines the dynamics of the Lake Naroch ecosystem by 9%, is also related to the process of primary production formation. Only the fifth main factor, which determined 7% of the dynamics of the ecosystem of Lake Naroch during the analyzed time period, controls the transfer of primary production to consumers of the first trophic level. Thus, our statistical study not only confirmed empirical regularities of the functioning of lake ecosystems, but for the first time enabled us to obtain quantitative assessments of the importance of each main factor for ecosystem development under specific conditions, depending on the trophicity of the water body. [ABSTRACT FROM AUTHOR]

Terrestrial organic matter (t-OM) has been recognized as an important cross-boundary subsidy to aquatic ecosystems. However, recent evidence has shown that t-OM contributes little to promote secondary production in lakes because it is a low-quality food for aquatic consumers. To resolve this conflict, we performed a field experiment using leaf litter as t-OM. In the experiment, we monitored zooplankton biomass in enclosures with and without addition of leaf litter under shaded and unshaded conditions and assessed food web changes with stable isotope analyses. We then examined whether or not leaf litter indeed stimulates lake secondary production and, if it does, which food chain, the detritus-originated food chain (“brown” food chain) or the algae-originated food chain (“green” food chain), contributes more to this increase. Analyses with stable isotopes showed the importance of t-OM in supporting secondary production under ambient lake conditions. However, the addition of the leaf litter increased the zooplankton biomass under unshaded conditions but not under shaded conditions. We found that phosphorus was leached from leaf litter at much faster rate than organic carbon and nitrogen despite its low content in the leaf litter. These results showed that leaf litter stimulated the increase in zooplankton biomass mainly through the green food chain rather than the brown food chain because the leaf litter supplied limiting nutrients (i.e., phosphorus) for primary producers.Our results indicate that the functional stoichiometry of the subsidized organic matter plays a crucial role in determining the relative importance of brown and green food chains in promoting production at higher trophic levels in recipient ecosystems.

The conducted research is aimed at assessing the current state of the tourist and recreational potential of the lake system in the region of North Kazakhstan (Kazakhstan). The research included the relationship between the distribution and natural diversity of reservoirs and landscapes and the density of the transport network of the studied region in the administrative division of the region. The aim of the research undertaken is to indicate the spatial differentiation of the conditions for t he development of tourism in relation to the degree of lake density and transport accessibility. The quantitative and qualitative characteristics of the lakes in terms of spatial diversity and transport accessibility in the region were presented. The anal ysis of the natural and recreational potential, with the use of statistical methods, satellite images, comparative analysis and field studies, made it possible to identify lake ecosystems that are already used or recommended for use as objects in tourism, as well as i n the national economy. The analysis of the road network allows to conclude that its density, despite the higher indicators than the national average, does not fully allow the use of the region's tourist potential and may constitute a barrier to its development.

The data of continuous monitoring of the Naroch Lakes system, which includes eutrophic Lake Batorino, mesotrophic Lake Myastro, and oligo-mesotrophic Lake Naroch, are used to search for the factors most affecting the long-term dynamics of the state of a lake ecosystem under a changing nutrient load. The set of continuous series of seasonal mean values of eight parameters of each ecosystem obtained in 1978–2015 is analyzed by singular spectrum analysis (SSA) and principal component analysis (PCA). The third principal component (F3), which contributed 8.2, 9.8, and 13.3% to the dynamics of ecosystems of Lake Batorino, Lake Myastro, and Lake Naroch, respectively, turns out to be connected with phyto- and zooplankton biomass, as well as with the parameters characterizing the processes of destruction and biochemical decomposition of organic matter. A comparison of statistical relationships and periods of the dominant cyclic components of principal components F3 and the associated parameters of ecosystems allow us to conclude that the interpretation of the third main factor under conditions of changing nutrient load depend on the characteristics of a particular ecosystem. In nutrient-rich ecosystems, it can be interpreted as the transfer of produced primary organic matter to consumers of the next trophic level, related to the structure of the food chain in the ecosystem. In the ecosystems where the process of primary production is limited by nutrient(s), this factor is represented by the available amount of nutrients, which is the third main factor affecting its long-term dynamics. [ABSTRACT FROM AUTHOR]

Littoral zones − referring to benthic areas above the light compensation depth − provide numerous ecosystem functions, including mediating light, temperature, and nutrient dynamics, and supporting important foraging and refuge areas for macroinvertebrates, fishes and water birds. Habitat assessments of littoral zones remain fundamental to lake and fisheries management, however traditional field surveys are time-intensive and limited in their spatial extent, whereas desktop evaluations using remote sensing and aerial imagery are cost prohibitive and require considerable data processing expertise. In light of these challenges, this study demonstrated the ability to use simple, cost-effective underwater videography to conduct lake-wide spatially-continuous assessments of littoral habitat. For lakes across a gradient of shoreline and riparian development in northwestern United States, we map the areal coverage of macrophytes, coarse woody habitat, bottom substrates, and artificial structures in littoral zones. Underwater videography represents a relevant tool for environmental monitoring because it allows for the estimation of littoral habitats at fine spatial grains across broad spatial extents. Data can also be obtained rapidly and at relatively low cost, providing a permanent record of habitat conditions that can used to monitor trends over time. [ABSTRACT FROM AUTHOR]

Climatic changes threaten freshwater resources and aquatic ecosystem health in the Sierra Nevada (California, USA), which has important consequences for millions of people and the world's fifth largest economy. However, the timing and magnitude of ecological changes driven by hydroclimate oscillations remain poorly understood in California's headwater region. Here, we develop a precisely dated, annually to decadally resolved lake sediment record of ecological change from the eastern Sierra Nevada that spans the last three millennia. Diatom paleoecology reveals a detailed history of abrupt limnologic transitions, best explained by modifications in water column stratification, mixing, and nutrient status in response to changing seasonality. Seasonally stratified conditions were registered during the Late Holocene Dry Period and the Medieval Climate Anomaly, illustrating the sensitivity of fossil diatoms to well‐known periods of drought. Yet the most striking feature of the record is the uniqueness of ~1840–2016 CE: a period of singularly strong water column stratification, increased algal diversity, and reduced diatom productivity consistent with unprecedented "hot droughts." The data demonstrate that hot–dry conditions of the Industrial Era altered lake state to conditions unseen in the past ~3180 years, and suggest that regional trends identified by historical monitoring began far earlier than previously recognized. Our record illustrates the profound influence of anthropogenic climate warming on high‐elevation lakes and the ecosystem services they provide in the Sierra Nevada, which hold implications for water quality and availability in California. [ABSTRACT FROM AUTHOR]

Process-based aquatic ecosystem models are increasingly being developed and used in freshwater ecology and other aquatic sciences, as they are powerful tools to gain a mechanistic understanding of ecological processes and inform policy and decision making in environmental management. Over the last decades, not only have these models increased considerably in number, but also in their degree of complexity, which can improve predictive capacity. Nevertheless, it is also because of the higher degree of complexity of many models of current widespread use, that not all the hypotheses and assumptions upon which they have been built are always met by the relatively simple experiments that characterise fundamental ecological research. This is true for both laboratory experiments and those carried out outdoors, under semi-controlled conditions. Examples of the latter are the mesocosms experiments through which several novel questions are nowadays being addressed. In this article, we present our views on why the development of new custom-tailored aquatic ecosystem models of varying degrees of complexity is still very much warranted and should, therefore, be encouraged despite arguments in favour of always increasing complexity and against the creation of new models that are largely based on previously published ones (‘reinventing the wheel’). Deciding on the right complexity level should be linked to the biological organisation levels that are relevant to the specific research questions, and to how much knowledge on the subject is already available. Spatial and temporal scales are additional factors that a modeller should weigh in when deciding on the complexity of a model. To address these needs in the long term, the modelling community needs to grow. Training a new generation of model developers will not only benefit other scientists to better design future experiments but will also facilitate interdisciplinary research and teamwork, approaches such as ensemble modelling, as well as the communication of science to managers and many other stakeholders.

Automated and reproducible methodology for assessing the ecological condition of lakes is essential for effective monitoring and facilitating the decision-making process aimed at achieving the stated environmental goals. At the same time, multidimensional measurement datasets are often an obstacle to drawing insightful conclusions, thus becoming an incentive for overly simplified analyzes. In this article, a set of measurements and ecological status assessment results for a collection of 499 lakes in Poland was used. Expert assessment process was recreated using the supervised kernel Support Vector Machine algorithm on dataset with reduced dimensionality, thus a model that automates the ecological assessment process was obtained. The use of the explanatory skill of latent variables made it possible to present the assessed objects along with their position in individual classes. The visualization of the results in reduced dimensionality increased, without interfering with the size of the classes, the informative evaluation potential, which should be considered as an acompanying assessment parameter in the future. The primary target of this paper is the ecological expert coping with automatization of assessment process and obtaining latent information for sense-making visual comprehension during consultations regarding ecosystem-oriented ecological decision making.

Ice‐off dates on lakes are some of the longest phenological records in the field of ecology, and some of the best evidence of long‐term climatic change. However, there has been little investigation as to whether the date of ice‐off on a lake impacts spring and summer ecosystem dynamics. Here, I analyzed 274 years of long‐term data from eight north temperate lakes in two climate zones to address whether lakes have ecological memory of ice‐off in the subsequent summer. Five metrics were investigated: epilimnion temperatures, hypolimnion temperatures, hypolimnetic oxygen drawdown, water clarity, and spring primary productivity. The response of the metrics to ice‐off date were variable across latitude and lake type. The northern set of lakes stratified quickly following ice‐off, and early ice‐off years resulted in significantly warmer hypolimnetic temperatures. Oxygen depletion in the hypolimnion was not impacted by ice‐off date, likely because in late ice‐off years the lakes did not fully mix. In the southern lakes, ice‐off date was not correlated to the onset of stratification, with the latter being a more dominant control on hypolimnetic temperature and oxygen. The implications of these findings is that as ice‐off date trends earlier in many parts of the world, the lakes that will likely experience the largest changes in spring and summer ecosystem properties are the lakes that currently have the longest duration of lake ice. In considering a future with warmer winters, these results provide a starting point for predicting how lake ecosystem properties will change with earlier ice‐off. Plain Language Summary: Lake ice is disappearing around the world. This slow loss of winter is a clear sign of climate change, but does the date of ice‐off impact spring and summer lake processes? Untangling a memory effect of ice‐off from other factors, such as spring and summer weather, requires decades of monitoring data. Here, 274 years of lake records from eight lakes in two climate zones were analyzed to investigate whether lakes have ecological memory of ice‐off. The response of lake temperature, oxygen concentrations, and water clarity to ice‐off date were variable across latitude and lake size and type. It was found that when lakes stratify immediately following ice‐off, bottom water conditions have ecological memory of the timing of ice‐off. However, in lakes with a short duration of lake ice, this memory effect fades. The implication of this finding is that as ice‐off date trends earlier in many parts of the world, the lakes that will likely experience the largest changes in spring and summer lake ecosystem properties are the lakes that currently have the longest duration of lake ice. Key Points: Ice‐off date has variable impacts on ecosystem properties across lake type and climatic zoneLakes with a short duration of ice have little ecological memory of ice‐off dateWhen lakes stratify immediately following ice‐off, ice‐off date impacts summer ecosystem properties [ABSTRACT FROM AUTHOR]

The conducted research is aimed at assessing the current state of the tourist and recreational potential of the lake system in the region of North Kazakhstan (Kazakhstan). The research included the relationship between the distribution and natural diversity of reservoirs and landscapes and the density of the transport network of the studied region in the administrative division of the region. The aim of the research undertaken is to indicate the spatial differentiation of the conditions for the development of tourism in relation to the degree of lake density and transport accessibility. The quantitative and qualitative characteristics of the lakes in terms of spatial diversity and transport accessibility in the region were presented. The anal ysis of the natural and recreational potential, with the use of statistical methods, satellite images, comparative analysis and field studies, made it possible to identify lake ecosystems that are already used or recommended for use as objects in tourism, as well as in the national economy. The analysis of the road network allows to conclude that its density, despite the higher indicators than the national average, does not fully allow the use of the region's tourist potential and may constitute a barrier to its development. [ABSTRACT FROM AUTHOR]

Results of the continuous monitoring of the Naroch lake system, which includes eutrophic Lake Batorino, mesotrophic Lake Myastro, and oligomesotrophic Lake Naroch, have been used to study the factors that largely affect the long-term dynamics of the lakes ecosystem under variable nutrient loading. A set of continuous series of average seasonal values of eight parameters from each ecosystem over 1978–2015 is analyzed using the SSA and PCA methods. The second principal component (F2), which contributes 15.3, 20.5, and 22.1% to the dynamics of the ecosystems of lakes Myastro, Batorino, and Naroch, respectively, is associated with three parameters that reflect the processes of formation and decomposition of the organic matter. A comparison of the periods of the dominant cyclical components of principal component F2 and related ecosystem parameters allows us to interpret the second main factor behind these components as activity from solar radiation. [ABSTRACT FROM AUTHOR]

As the global climate warms, the fate of lacustrine fish is of huge concern, especially given their sensitivity as ectotherms to changes in water temperature. The Arctic charr (Salvelinus alpinus L.) is a salmonid with a Holarctic distribution, with peripheral populations persisting at temperate latitudes, where it is found only in sufficiently cold, deep lakes. Thus, warmer temperatures in these habitats particularly during early life stages could have catastrophic consequences on population dynamics. Here, we combined lake temperature observations, a 1-D hydrodynamic model, and a multi-decadal climate reanalysis to show coherence in warming winter water temperatures in four European charr lakes near the southernmost limit of the species' distribution. Current maximum and mean winter temperatures are on average ~ 1 °C warmer compared to early the 1980s, and temperatures of 8.5 °C, adverse for high charr egg survival, have frequently been exceeded in recent winters. Simulations of winter lake temperatures toward century-end showed that these warming trends will continue, with further increases of 3–4 °C projected. An additional 324 total accumulated degree-days during winter is projected on average across lakes, which could impair egg quality and viability. We suggest that the perpetuating winter warming trends shown here will imperil the future status of these lakes as charr refugia and generally do not augur well for the fate of coldwater-adapted lake fish in a warming climate. [ABSTRACT FROM AUTHOR]

Aerobic anoxygenic phototrophic (AAP) bacteria are a phylogenetically diverse and ubiquitous group of prokaryotes that use organic matter but can harvest light using bacteriochlorophyll a. Although the factors regulating AAP ecology have long been investigated through field surveys, the few available experimental studies have considered AAPs as a group, thus disregarding the potential differential responses between taxonomically distinct AAP assemblages. Here, we used sequencing of the pufM gene to describe the diversity of AAPs in 10 environmentally distinct temperate lakes, and to investigate the taxonomic responses of AAP communities in these lakes when subjected to similar experimental manipulations of light and predator removal. The studied communities were clearly dominated by Limnohabitans AAP but presented a clear taxonomic segregation between lakes presumably driven by local conditions, which was maintained after experimental manipulations. Predation reduction (but not light exposure) caused significant compositional shifts across most assemblages, but the magnitude of these changes could not be clearly related to changes in bulk AAP abundances or taxonomic richness of AAP assemblages during experiments. Only a few operational taxonomic units, which differed taxonomically between lakes, were found to respond positively during experimental treatments. Our results highlight that different freshwater AAP communities respond differently to similar control mechanisms, highlighting that in‐depth knowledge on AAP diversity is essential to understand the ecology and potential role of these photoheterotrophs. [ABSTRACT FROM AUTHOR]

An assessment is made of the lake resources of Russia in particular regions identified on the basis of the genetic principle, i. e. an approximate even-aged origin of most lake basins within the territory. It was determined that a little less than two-thirds of all water bodies are located on the coastal plains of the seas of the Arctic and Pacific Oceans, which account for one-fifth of the country's area. The climatic conditions of the coastal zone are favorable for the existence of lakes, most of which owe their origin to relatively recent (on a geological time scale) marine transgressions. The total water surface area of the coastal plains makes up about 40% of the total area of all water bodies of Russia; however, they contains only 1.3% of the total water volume of the country because most of these water bodies are shallow. The territories that were previously under the cover of the Valdai glaciation occupy about 4% of the country, their water surface area is about 18%, and the number of water bodies located there makes up 6% of the total number for Russia. The lakes remaining on the site of the Valdai glaciation contain more than 5% of the total volume of the country's waters. About 90% of the entire lake waters are concentrated in mountainous regions, where a significant part of the deepest and most capacious lakes including Baikal are located, but the number of water bodies is only 5.6% of the total number in the country, and the water surface area is 13%. It is shown that since the origin of the lakes is primarily determined by the geological history of the region, their distribution over the territory is rather weakly dependent on climatic factors. An increased lake percentage is observed in regions that had ridded themselves of sea waters and glacial cover at the interface of the Late Pleistocene and the Holocene; within these regions, changes in lake percentage are governed by differences in sculptural landforms. [ABSTRACT FROM AUTHOR]

• FPV coverage is predicted to drive ecological impacts in freshwater ecosystems. • This study represents a novel effort to quantify FPV coverage in lakes worldwide. • Worldwide, FPV coverage averaged 34.2 % (±22.0 SD, n = 494) • Lake size and morphology drive FPV coverage, which varies strongly between continents. • Smaller lakes with simpler shorelines showed higher FPV coverage, intensifying ecological risks. Floating Photovoltaic (FPV) deployments are accelerating worldwide and FPV coverage on water surface can strongly influence their ecological impacts. Yet, a global assessment of their characteristics is still lacking. We identified 643 FPV power plants constructed across the globe. We found that FPV power plants currently exist in 28 countries, predominantly concentrated in Asia. FPV coverage was highly variable between lakes, ranging from 0.004 % to 89.9 % of lake surface area. Overall, FPV coverage averaged 34.2 % (±22 SD, n = 494), varying significantly across continents. FPV coverage was significantly driven by lake size and morphological complexity, with smaller lakes and lakes with simplified morphology having higher FPV coverage. The high variability in FPV coverage worldwide suggests a high context-dependency of their ecological impacts that will likely be stronger in small lakes with higher FPV coverage. [ABSTRACT FROM AUTHOR]

The escalating occurrence of toxic cyanobacterial blooms worldwide is a matter of concern. Global warming and eutrophication play a major role in the regularity of cyanobacterial blooms, which has noticeably shifted towards the predomination of toxic populations. Therefore, understanding the effects of cyanobacterial toxins in aquatic ecosystems and their advantages to the producers are of growing interest. In this paper, the current literature is critically reviewed to provide further insights into the ecological contribution of cyanotoxins in the variation of the lake community diversity and structure through interspecies interplay. The most commonly detected and studied cyanobacterial toxins, namely the microcystins, anatoxins, saxitoxins, cylindrospermopsins and β-N-methylamino-L-alanine, and their ecotoxicity on various trophic levels are discussed. This work addresses the environmental characterization of pure toxins, toxin-containing crude extracts and filtrates of single and mixed cultures in interspecies interactions by inducing different physiological and metabolic responses. More data on these interactions under natural conditions and laboratory-based studies using direct co-cultivation approaches will provide more substantial information on the consequences of cyanotoxins in the natural ecosystem. This review is beneficial for understanding cyanotoxin-mediated interspecies interactions, developing bloom mitigation technologies and robustly assessing the hazards posed by toxin-producing cyanobacteria to humans and other organisms.

The species composition and biological parameters of fish from Lake Syamozero areas (Republic of Karelia) near rainbow trout farming cages were studied. Evidence was found that the main pollutants in waters harboring commercial rainbow trout farming facilities are nutrients (nitrogen and phosphorus) and excreted fish metabolites, which promote eutrophication. Our study showed that operations of the trout farm have induced structuralmodifications in the lake’s fish population. The most abundant fish species in the current aquaculture area used to be the vendace Coregonus albula, whereas now there prevailthe roach Rutilus rutilus, perch Perca fluviatilis and ruffe Gymnocephalus cernuus. Significant variations were observed in the biomass of fish aggregations across the lake during the study period. Fish density indices near cage lines were 1.5‑fold higher than in open water areas. One of the main presumable reasons for local fish species to aggregate near cages is to feed on trout fodders. We also noted that the rates of lengthand weight increment in roach, perch and ruffe around the cages were significantly higher than in remote parts of the lake, which is also due to additional dietary supply of trout fodder residues washed out of the cages.

This study evaluates the differences in mineral and toxic trace element concentrations of Nile tilapia (Oreochromis niloticus) tissues from three aquatic ecosystems in Ethiopia—Lake Ziway, Lake Langano, and Gilgel Gibe reservoir—with a focus on edible (fillet) and discarded (digestive tract, gills, skin, and liver) parts. A total of sixty (n = 60) Nile tilapia samples were collected, comprising twenty (n = 20) fish from each lake, and analyzed by inductively coupled plasma mass spectrometry. All elements varied markedly among tissues and between the lakes. Some differences in element concentrations were attributed to differences in nutrient load in the ecosystems and the function of the tissues. For instance, the calcium concentrations in skin and gill were distinctly higher in fish from calcium-rich Lake Langano. The d iscarded parts were richer in essential trace elements, showing an opportunity to promote their use in human nutrition to increase the intake of important minerals. However, the accumulation of elements toxic to humans, such as aluminum, should be monitored and, in particular, controlled when rearing these fish in aquaculture.

Lake Baikal is a unique oligotrophic freshwater lake with unusually cold conditions and amazing biological diversity. Studies of the lake’s viral communities have begun recently, and their full diversity is not elucidated yet. Here, we performed DNA viral metagenomic analysis on integral samples from four different deep-water and shallow stations of the southern and central basins of the lake. There was a strict distinction of viral communities in areas with different environmental conditions. Comparative analysis with other freshwater lakes revealed the highest similarity of Baikal viromes with those of the Asian lakes Soyang and Biwa. Analysis of new data, together with previously published data allowed us to get a deeper insight into the diversity and functional potential of Baikal viruses; however, the true diversity of Baikal viruses in the lake ecosystem remains still unknown. The new metaviromic data will be useful for future studies of viral composition, distribution, and the dynamics associated with global climatic and anthropogenic impacts on this ecosystem.

The system of the Naroch lakes, which includes the eutrophic Lake Batorino, the mesotrophic Lake Myastro, and the oligo-mesotrophic Lake Naroch, serves as a model object for the study of the factors initially influencing the state of a particular lake ecosystem affected by variable nutrient loading. Throughout the 1970s–2000s, these lakes have been going through the stages of anthropogenic eutrophication, deeutrophication, and benthification. A set of continuous data based on the seasonal means ​​of the eight parameters from each lake for the period 1978–2015 has been analyzed by Principal Component and Singular Spectrum Analysis (SSA, or Caterpillar). In addition, we consider the dynamics of the trophic index of each lake, which had been calculated earlier at the same data set. The first main component is the stability of the lake ecosystem under variable nutrient loading, which is inversely related to the trophic state of the water body. This component determines the condition of the Batorino, Myastro and Naroch lakes by 63, 65, and 43% respectively. [ABSTRACT FROM AUTHOR]

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An algorithm of a dynamic mass-balance model emulating the biotic energy flow in a planktonic community with the involvement of microbial organisms has been developed. The abiotic input parameters of the model are the latitude, mean depth of the water body, total phosphorus content, and water color. The model makes it possible to forecast the biomass and production of key plankton groups. It is shown that the food-base production for fish and their growth are determined by the degree of protozoan plankton involvement in the trophic web. [ABSTRACT FROM AUTHOR]

Highlights • The lake bacterial abundance is shown to grow as the trophic state index increases. • The lake bacterioplankton fluctuations are not correlated with the chlorophyll ones. • The bacterioplankton oscillations are under a tangible temperature control. • Bacterial abundance is assumed to be an invariant measure of the lake trophic state. Abstract Trophic state is a key biological characteristic of water body that integrates the main hydroecological factors. However, the character of the interrelation between bacterioplankton dynamics and the lake trophic state remained obscure. The long-term (1995–2015) monitoring data were carried out to examine the relations between bacterial parameters (abundance, biomass, and cell biovolume) and main hydroecological factors (chlorophyll, phosphorus, nitrogen, organic matter) in three water bodies: Lake Batorino, Lake Myastro, and Lake Naroch, which differ by trophic state. The results of the analysis of the data show that the growth of the chlorophyll-based trophic state index (TSI Chl) as well as dissolved organic carbon (DOC), total phosphorus (TP) and 5-day biochemical oxygen demand (BOD 5) in the chain Lake Naroch – Lake Myastro – Lake Batorino is accompanied by a linear increase in the bacterioplankton abundance, while fluctuations of bacterioplankton abundances and trophic state parameters in each of the Naroch Lakes are not correlated with each other. It is shown that temperature is the factor, which impacts seasonal bacterioplankton dynamics. The ratio of the time-averaged abundance of bacteria in July to the time-averaged abundance of bacteria in May remains virtually unchanged compared to the ratio between July and October. However, similar ratios for chlorophyll- a undergo significant changes. This result leaves room for further investigation of the factors, which can influence trophic state of the lakes, on the assumption that bacterial abundance is considered as an invariant measure. [ABSTRACT FROM AUTHOR]

Understanding the assembly and turnover of microbial communities is crucial for gaining insights into the diversity and functioning of lake ecosystems, a fundamental and central issue in microbial ecology. The ecosystem of Taihu Lake has been significantly jeopardized due to urbanization and industrialization. In this study, we examined the diversity, assembly, and turnover of bacterial and fungal communities in Taihu Lake sediment. The results revealed strong bacterial stochasticity and fast fungal turnover in the sediment. Significant heterogeneity was observed among all sediment samples in terms of environmental factors, especially ORP, TOC, and TN, as well as microbial community composition and alpha diversity. For instance, the fungal richness index exhibited an approximate 3-fold variation. Among the environmental factors, TOC, TN, and pH had a more pronounced influence on the bacterial community composition compared to the fungal community composition. Interestingly, species replacement played a dominant role in microbial beta diversity, with fungi exhibiting a stronger pattern. In contrast, stochastic processes governed the community assembly of both bacteria and fungi, but were more pronounced for bacteria (R2 = 0.7 vs. 0.5). These findings deepen the understanding of microbial assembly and turnover in sediments under environmental stress and provide essential insights for maintaining the multifunctionality of lake ecosystems. [Display omitted] • Environmental heterogeneity exists in Taihu Lake sediments, especially in nutrients. • Species replacement governs bacterial and fungal beta diversity. • Fungal turnover occurs faster than bacteria. • Stochastic processes shape the microbial assembly in Taihu Lake sediments. • Bacteria exhibits higher species dispersion than fungi. [ABSTRACT FROM AUTHOR]

Abstract: Most of the hypersaline lakes located in the arid part of the Crimea have been undergoing anthropogenic transformations. We concentrate on the impact of the established water storage reservoir on the marine Kyzyl-Yar Lake (Western Crimea) over the period from 1985 to 2017. As a result of water seepage from the reservoir, the lake salinity decreased from 162 g/L in 1985 to 2-3 g/L in 2005 and subsequently remained steady at this level. Over 20 years, the lake changed from a hypersaline to freshwater lake. The accompanying changes included an altered ratio of ion concentrations in the water column and interstitial waters and increased Ca2+/Na+ and indicators. Substantial shifts occurred in the structure of the biological diversity and conditions of the bottom deposits, such as the disappearance of branchipoda crustaceans of the genus Artemia, which had been practically the only representative of the local fauna before, and the dominance of new species Cladocera and Cyclopoida in plankton. [ABSTRACT FROM AUTHOR]

The need to protect biostructure is increasingly recognized, yet empirical studies of how human exploits affect ecological networks are rare. Studying the effects of variation in human disturbance intensity from decades past can help us understand and anticipate ecosystem change under alleviated or amplified disturbance over decades to come. Here, we use stable isotopes and an innovative analytical approach to compare the food webs of two akin lake ecosystems subject to disparate water use regimes, a pervasive, yet unappreciated stressor. We show that intensive water use (persistent, early season, rapid lake-level drawdown) can compress trophic diversity by 46%, necessitating reorganization of biostructural elements configuring lake food webs. Compression occurred over the δ13C axis indicating erosion of basal trophic diversity, but food chain length remained intact over the period and intensity of disturbance examined. This study demonstrates the potential for water use, like other disturbances (warming, eutrophication, and invasive species), to mute opportunity for benthic-pelagic coupling and benefits to lake food webs and the inherent capacity of lake ecosystems to adapt to stress. Trophically compressed lakes may be less able to adapt to intensified water use. [ABSTRACT FROM AUTHOR]

Variable sensitivity of organisms to silver nanoparticles (AgNPs) caused by changes in physico-chemical variables in aquatic ecosystems is receiving increasing attention. Variables such as dissolved organic carbon, pH, light, the presence of algae and bacteria, dissolved oxygen and different ions have all been studied individually, but it is still unclear how these variables in combination alter AgNP toxicity in natural ecosystems. Here we examined AgNP toxicity on survival of wild-caught Daphnia using AgNP suspensions placed in water from several different lakes at the IISD-Experimental Lakes Area, which span a gradient of water quality parameters. The partitioning of AgNPs between particulate and dissolved organic matter fractions was also assessed due to the potential for algal sequestration and detoxification of AgNPs. We found that toxicity varied between lakes with LC 50 values ranging between 34 and 292 μg Ag L −1 . Time of year in terms of days since ice-off and carbon to nitrogen ratios of particulate matter were the major predictors of toxicity between ecosystems. Total dissolved phosphorus, dissolved organic carbon, and particulate carbon to phosphorus ratios also played minor roles in influencing survival of Daphnia between water types. We found variable partitioning of silver into the particulate fraction within lakes and no significant differences between lakes. Silver associated with particulate organic matter increased with increasing concentrations of AgNPs in the ecosystem. Overall, we found strong evidence that AgNP toxicity is highly context dependent in natural lake ecosystems. [ABSTRACT FROM AUTHOR]

Modern biodiversity research focuses on multiple diversity facets because different indices may describe different ecological and environmental processes, as well as the effects of varied disturbances of natural and anthropogenic origins. We investigated littoral macroinvertebrate diversity in a large boreal lake system and specifically explored congruence of indices within and between the three diversity facets: species diversity, functional diversity and taxonomic distinctness. First, we found that the indices of taxonomic distinctness were the most sensitive indicators of eutrophication. Second, we observed that most correlations between the indices within the same diversity facet, and between the indices of functional and species diversity, were relatively strong. However, the indices of taxonomic distinctness (Δ+ and Λ+) were weakly associated with other metrics of diversity, emphasising the importance of taxonomic distinctness as a complementary dimension of biodiversity. Therefore, our observations support the importance to examine multiple facets for mapping biodiversity or for assessing the effects of anthropogenic disturbances on biological communities. [ABSTRACT FROM AUTHOR]