Lake Communities Research Articles

Microbial assemblages in Arctic coastal thermokarst lakes and lagoons.

Several studies have investigated changes in microbial community composition in thawing permafrost landscapes, but microbial assemblages in the transient ecosystems of the Arctic coastline remain poorly understood. Thermokarst lakes, abrupt permafrost thaw features, are widespread along the pan-Arctic coast and transform into thermokarst lagoons upon coastal erosion and sea-level rise. This study looks at the effect of marine water inundation (imposing a sulfate-rich, saline environment on top of former thermokarst lake sediments) on microbial community composition and the processes potentially driving microbial community assembly. In the uppermost lagoon sediment influenced from marine water inflow, the microbial structures were significantly different from those deeper in the lagoon sediment and from those of the lakes. In addition, they became more similar along depth compared with lake communities. At the same time, the diversity of core microbial consortia community decreased compared with the lake sediments. This work provides initial observational evidence that Arctic thermokarst lake to lagoon transitions do not only substantially alter microbial communities but also that this transition has a larger effect than permafrost thaw and lake formation history.

Diazotrophic community in the sediments of Poyang Lake in response to water level fluctuations.

Water level fluctuations (WLFs) are typical characteristic of floodplain lakes and dominant forces regulating the structure and function of lacustrine ecosystems. The sediment diazotrophs play important roles in contributing bioavailable nitrogen to the aquatic environment. However, the relationship between the diazotrophic community and WLFs in floodplain lakes is unknown. In this paper, we carried out a comprehensive investigation on the alpha diversity, abundance, composition and co-occurrence network of the sediment diazotrophs during different water level phases in Poyang Lake. There were no regular variation patterns in the alpha diversity and abundance of the sediment diazotrophs with the water level phase transitions. The relative abundance of some diazotrophic phyla (including Alphaproteobacteria, Deltaproteobacteri, Euryarchaeota, and Firmicutes) and genera (including Geobacter, Deferrisoma, Desulfuromonas, Rivicola, Paraburkholderia, Methylophilus, Methanothrix, Methanobacterium, and Clostridium) was found to change with the water level phase transitions. The results of ANOSIM, PerMANOVA, and DCA at the OTU level showed that the diazotrophic community structure in the low water level phase was significantly different from that in the two high water level phases, while there was no significant difference between the two high water level phases. These results indicated that the diazotrophic community was affected by the declining water level in terms of the composition, while the rising water level contributed to the recoveries of the diazotrophic community. The diazotrophs co-occurrence network was disrupted by the declining water level, but it was strengthened by the rising water level. Moreover, redundancy analysis showed that the variation of the diazotrophic community composition was mostly related to sediment total nitrogen (TN) and total phosphorous (TP). Interestingly, the levels of sediment TN and TP were also found to vary with the water level phase transitions. Therefore, it might be speculated that the WLFs may influence the sediment TN and TP, and in turn influence the diazotrophic community composition. These data can contribute to broadening our understanding of the ecological impacts of WLFs and the nitrogen fixation process in floodplain lakes.

Salinity-induced succession of phototrophic communities in a southwestern Siberian soda lake during the solar activity cycle

A variety of lakes located in the dry steppe area of southwestern Siberia are exposed to rapid climatic changes, including intra-century cycles with alternating dry and wet phases driven by solar activity. As a result, the salt lakes of that region experience significant fluctuations in water level and salinity, which have an essential impact on the indigenous microbial communities. But there are few microbiological studies that have analyzed this impact, despite its importance for understanding the functioning of regional water ecosystems. This work is a retrospective study aimed at analyzing how solar activity-related changes in hydrological regime affect phototrophic microbial communities using the example of the shallow soda lake Tanatar VI, located in the Kulunda steppe (Altai Region, Russia, southwestern Siberia). The main approach used in this study was the comparison of hydrochemical and microscopic data obtained during annual field work with satellite and solar activity data for the 12-year observation period (2011–2022). The occurrence of 33 morphotypes of cyanobacteria, two key morphotypes of chlorophytes, and four morphotypes of anoxygenic phototrophic bacteria was analyzed due to their easily recognizable morphology. During the study period, the lake surface changed threefold and the salinity changed by more than an order of magnitude, which strongly correlated with the phases of the solar activity cycles. The periods of high (2011–2014; 100–250 g/L), medium (2015–2016; 60 g/L), extremely low (2017–2020; 13–16 g/L), and low (2021–2022; 23–34 g/L) salinity with unique biodiversity of phototrophic communities were distinguished. This study shows that solar activity cycles determine the dynamics of the total salinity of a southwestern Siberian soda lake, which in turn determines the communities and microorganisms that will occur in the lake, ultimately leading to cyclical changes in alternative states of the ecosystem (dynamic stability).

Cultural Fluctuation of Lake Communities by the Shrinkage of Lake Limboto, Indonesia

The fluctuating conditions of Lake Limboto have greatly affected the activities of people living around the lake. The shallowing and narrowing of the lake poses a significant problem to local people’s survival. The lake is predicted to disappear by 2030, which will consequentially lead to a diminishment in the productivity of the lake. This article aims to analyze how the communities around the lake respond in their daily activities to the transformation of the lake and the shocking prediction about its lifespan. This study uses an interdisciplinary approach by integrating multiple fields of study to understand and address the problems regarding this issue. This research comprised a literature review, field survey, and in-depth interview process around the lake. This research relied on the framework of cultural studies to analyze the survival and resilience of the people around the lake, gaining an understanding of their special daily activities. The results of this study show that some people are aware of the lake’s gradual recession, but they have not prepared for it, treating the problem as only a government affair. They continue to live at the lake’s shores, enduring even amidst impoverished conditions.

LITERATUR REVIEW: PEMANFAATAN METABARCODING DNA LINGKUNGAN UNTUK MENGANALISIS KEANEKARAGAMAN HAYATI IKAN

Background: Environmental DNA (eDNA) metabarcoding is a new method for assessing biodiversity in which samples are taken from the environment via water, sediment or air from which DNA is extracted, and then amplified using common or universal primers in a polymerase chain reaction and sequenced using next-generation DNA. sequencing to produce thousands to millions of sequences. From this data, the presence of species can be determined, and overall biodiversity can be assessed.. Methods: The method used is a literature review using reputable national and international journals Results: Based on the results of the literature review, the use of eDNA metabarcoding can be used to analyze fish biodiversity. eDNA metabarcoding can be analyzed with primary data, databases, and bioinformatic pipelines. Conclusion: eDNA metabarcoding has been widely used to study fish communities in lakes and rivers, as well as coastal fish communities. Despite its considerable ability to detect fish species in large aquatic systems, many methods still need to be understood to improve the quality of primers, databases, and pipelines for analyzing fish biodiversity

Responses by benthic invertebrate community composition to dissolved organic matter in lakes decline substantially above a threshold concentration

Abstract Dissolved organic matter (DOM), often measured as dissolved organic carbon (DOC), plays a fundamental role in influencing the structure and function of lake ecosystems. Due to the myriad ecosystem effects of DOM, widespread observations of long‐term increasing DOM concentrations have received much attention from ecologists. DOM positively influences primary production and consumer production at low concentrations due to the fertilising influence of bound nutrients. However, beyond a unimodal peak in production, a reduced light environment may result in a negative effect on production. This unimodal model has been largely developed and tested in lakes with low to moderate DOM concentrations (i.e., typically ≤10 mg/L DOC). To understand ecological responses in lakes across a larger range in DOM concentrations, we examined the response of benthic invertebrate communities in 148 Swedish lakes with DOM concentrations ranging between 0.67 and 32.77 mg/L DOC. We found that increasing DOM concentrations had a strong effect on invertebrate community composition below c. 10 mg/L. Across this range, abundances of individual taxa both increased and decreased, probably in response to environmental change induced by DOM. However, in lakes above this concentration, increasing DOM had minimal influence on community composition. As DOM concentrations continue to increase, faunal communities in lakes below this 10 mg/L DOC threshold are likely to undergo substantial change whereas those above this threshold are likely to be minimally impacted.

Interactive effects of climate-atmospheric cycling on aquatic communities and ecosystem shifts in mountain lakes of southeastern Tibetan Plateau

Recent climate warming and atmospheric reactive nitrogen (Nr) deposition are affecting a broad spectrum of physical, ecological and human systems that may be irreversible on a century time scale and have the potential to cause regime shifts in ecological systems. These changes may alter the limnological conditions with important but still unclear effects on lake ecosystems. We present changes in cladoceran with comparisons to diatom assemblages over the past ~200 years from high-resolution, well-dated sediment cores retrieved from six high mountain lakes in the southeastern (SE) margin of the Tibetan Plateau. Our findings suggest that warming and the exponential increase of atmospheric Nr deposition are the major drivers of ecological regime changes. Shifts in cladoceran and diatom communities in high alpine lakes began over a century ago and intensified since 1950 CE, indicating a regional-scale response to anthropogenic climate warming. Zooplankton in the forest lakes showed asynchronous trajectories, with increased Nr deposition as a significant explanatory factor. Forest lakes with higher dissolved organic carbon (DOC) concentrations partially buffered the impacts of Nr deposition with little structural change, while lakes with low DOC display symptoms of resilience loss related to Nr deposition. Biological community compositional turnover in subalpine lakes has shown marked shifts, equivalent to those of low-elevation lakes strongly affected by direct human impacts. This suggests that local effects override climatic forcing and that lake basin features modified by anthropogenic activity act as basin-specific filters of common forcing. Our results indicate that snow and glacial meltwaters along with nutrient enrichment related to climate warming and atmospheric Nr deposition, represent major threats for lake ecosystems, even in remote areas. We reveal that climate and atmospheric contaminants will further impact ecological conditions and alter aquatic food webs in higher altitude biomes if climate and anthropogenic forcing continue.

Nutrient availability is the main driver of nanophytoplankton phago-mixotrophy in North American lake surface waters

Abstract There has been limited research on the abiotic and biotic factors affecting the prevalence of phago-mixotrophy (prevMixo) among nanophytoplankton across freshwater ecosystems. In recent years, large-scale sampling campaigns like the EPA-National Lakes Assessment and the NSERC LakePulse survey have generated surface water community composition data for hundreds of lakes across North America, covering large environmental gradients. We present results from our analyses of the nanophytoplankton community data from these two surveys, focusing on a taxonomic comparison of the mixoplankton communities across ecoregions and multivariate analyses of the environmental drivers of the prevMixo. We identified potentially phago-mixotrophic taxa in the majority of sites and across all ecozones sampled. Lake trophic state was identified as the main predictor of nanophytoplankton resource-acquisition strategy assemblages, with lower prevalence and diversity of mixoplankton communities in more eutrophic lakes. Lake trophic state also controlled the composition of the mixoplankton community and increased total phosphorus levels were associated with a loss of mixoplankton diversity. This study represents the most comprehensive assessment of the prevMixo in lake nanophytoplankton communities to date spanning hundreds of sites and a dozen ecozones.

The role of participatory action research (PAR) in the emergence of self-determined Indigenous research responding to major societal issues

In recent decades, there has been growing criticism that research has long been conducted ‘on’ Indigenous peoples rather than ‘with’ or ‘for’ them. In response to this, in 1999, Linda Tuhiwai Smith published a critical analysis of colonialism in Western research, arguing for the decolonisation of knowledge and the implementation of new co-constructed projects that respond to societal concerns, rely on methodologies rooted in local knowledge, and use participatory action research approaches. In a seven-year project (2010–17) in Nunavut, Canada, we adopted this approach, using participatory action research to co-construct research questions in collaboration with the Inuit community of Baker Lake (Qamani’tuaq) on issues that most concern them, such as mining impacts and youth future. This article discusses the TUKTU project, analysing its development and the advantages and limitations of Indigenous participatory action research, conceived and conducted by the people it concerns, and based on their vision of the world, valorising their knowledge and contributing to their empowerment.

Effect of local and regional factors on the structure of the fish communities associated with aquatic macrophyte stands in oxbow lakes on the Amazon floodplain.

The Amazon floodplain is home to an extremely high diversity of fish, with lakes playing an important role in the establishment of this biological richness. These lacustrine environments are subject to constant fluctuations caused by the annual flood pulse, with local factors and other regional patterns also contributing to the variation in fish community structure. The present study verified how local (depth and transparency of the water, the size and species composition of the macrophyte stands) and regional factors (spatial distribution of the stands and the hydrological phase) influence the structure of the fish community of the floodplain lakes of the Môa River, in northern Brazil. Fish species richness was influenced by the depth of the water and the spatial distribution of the macrophyte stands. Fish species composition was influenced by local environmental variables, spatial structure, and the hydrological phase. However, variation partitioning indicated that only the hydrological phase explained the variation in fish composition. These findings indicate that the local environment, the spatial structure, and the hydrological phase drive changes in the structure of the fish communities associated with aquatic macrophytes in the floodplain lakes of the Amazon basin.

Features of microbial communities in fresh lakes of Buryatia

The taxonomic composition of microbial communities of eight large fresh lakes of Buryatia was studied. These lakes are Baikal, Kotokel, Gusinoye, Shchuchye and lakes of the Eravno-Kharginskaya group (Isinga, Gunda, Sosnovoe, Bolshoe Eravnoe). They have water management, fishery and recreational significance. At the phylum level, the microbial communities of the studied lakes were similar but the phyla abundance was varied. They consisted of typical freshwater taxa Pseudomonadota, Actinobacteriota, Bacteroidota, Cyanobacteriota, Firmicutes, Planctomycetes and Verrucomicrobia. At the genus level, Acinetobacter and Pseudomonas were numerous in all lakes. Other dominant taxa were Flavobacterium, hgcI clade in the fresh lakes of the Baikal region and Exiguobacterium, Klebsiella in the Eravno-Kharginskaya lakes. The feature of Eravno-Kharginskie lakes was the abundance of the genera Exiguobacterium and Klebsiella, as well as the detection of sanitary-significant bacteria. These facts may indicate pollution as a result of pressing various factors, including anthropogenic ones.

Rising Together in Response to the COVID-19 Pandemic

The COVID-19 pandemic created a socioeconomic shock that heavily impacted coastal and Great Lakes communities. In response, the NOAA National Sea Grant Program tailored efforts to meet local and regional needs, with an emphasis on research, extension, and education. This paper presents an overview of four projects that illustrate Sea Grant’s priorities in action and how Sea Grant was able to respond collaboratively to the pressing needs of coastal communities and economies during the COVID-19 pandemic. The case studies also demonstrate how Sea Grant provides expertise to protect and restore coastal ecosystems, supports resilient communities and economies, promotes sustainable fisheries and aquaculture, enables an environmentally literate public, and bolsters a skilled workforce that serves the needs of coastal communities and ecosystems. They also demonstrate how these experiences made coastal communities and Sea Grant more resilient to unexpected disruptions in the long term, and how these efforts shaped Sea Grant and who it serves in times of crisis and beyond.

Population dynamics of amphibian community in Lake Çıldır, Northeastern Anatolia

Knowledge on life history traits and population dynamics of amphibians from northeastern Anatolia is limited. This results in a heavy reliance on published data regarding the European and Caucasian counterparts of the Anatolian populations in local conservation studies. The present study evaluated the phenology, age structure, population size, and population structure of the amphibian community in Lake Çıldır, northeastern Anatolia, Turkey. The site was surveyed between April 2017 and July 2019, detecting the presence of Bufo verrucosissimus, Bufotes viridis sitibundus, Pelophylax ridibundus, and Rana macrocnemis. The estimated population size ranged from 553 to 789 individuals for P. ridibundus and from 404 to 655 individuals for R. macrocnemis. The estimated mean capture probability was 0.09-0.10 for P. ridibundus and 0.08-0.11 for R. macrocnemis. The mean survival rates were estimated at 0.40-0.60 for P. ridibundus and 0.24-0.56 for R. macrocnemis. A male-biased sex ratio was observed for all species. The mean age was estimated at 5.28 years (2-9) for P. ridibundus, 4.32 years (2-6) for R. macrocnemis, and 5.55 years (3-9) for B. viridis sitibundus. Depending on weather conditions, the amphibian species emerged from brumation in the second half of April, and the breeding period took place between the end of April and June. The metamorphosis was attained in 55-125 days for P. ridibundus, 44-124 days for R. macrocnemis, and 56-128 days for B. viridis sitibundus, depending on weather conditions. The amphibian community of Lake Çıldır comprises healthy frog and toad populations, whose primary threats appear to be weather fluctuations and climate change. In contrast to their western Anatolian conspecifics, the studied amphibians suffered limited habitat loss and degradation, rendering them effective candidates as indicator species for climate change studies.

Lakes-scale pattern of eukaryotic phytoplankton diversity and assembly process shaped by electrical conductivity in central Qinghai-Tibet Plateau.

Phytoplankton are the main primary producers in aquatic ecosystems and play an important role in food web and geochemical cycles. Its diversity, community structure, and assembly process are influenced by several factors. Alpine lake ecosystems are relatively weak and extremely sensitive to global climate change. However, the impact of climate change on phytoplankton in Qinghai-Tibet Plateau lakes and their responses are still unclear. In this study, we analyzed the diversity, environmental drivers, and assembly process of phytoplankton community in the central QTP lakes. The phytoplankton of these lakes can be primarily distinguished into freshwater and brackish types, with significant differences in species diversity and community dissimilarity. Both shared nearly same key environmental factors that significantly affecting phytoplankton such as EC, and brackish lakes were also positively correlative with TN. Stochastic process was predominant in phytoplankton assembly. Additionally, freshwater and brackish lakes were dominated by dispersal limitation and heterogeneous selection respectively. Alpine lakes had significant EC thresholds, and their diversity and assembly processes changed significantly around the thresholds. The present findings have important implications for understanding and predicting the response of lake phytoplankton communities to climate change and for making decisions to protect the ecological resources of alpine lakes.

Effects of Multiple Environmental Stressors on Zoobenthos Communities in Shallow Lakes: Evidence from a Mesocosm Experiment

Multiple stressors, including climate change, eutrophication, and pesticide contamination, are significant drivers of the decline in lake zoobenthos. Zoobenthos play a crucial role in aquatic ecosystems, impacting energy dynamics, nutrient cycling, and sediment degradation. However, these stressors have led to a decrease in the abundance and diversity of zoobenthos, resulting in notable changes in species composition and structure. Eutrophication typically increases zoobenthos abundance while reducing taxonomic diversity. Climate change, such as warming and heatwaves, also affects the zoobenthos community structure, with different species exhibiting varying levels of adaptability to temperature changes. Additionally, pesticides like imidacloprid have negative effects on the survival and growth of zoobenthos. However, the interactions between imidacloprid and other stressors remain understudied. Here, we used 48 mesocosms (2500 L) to simulate shallow lakes. We combined nutrient loading, sustained warming, and the imidacloprid pesticide to test how these stressors interactively influence the survival and community of zoobenthos. The experimental results demonstrate that elevated temperatures have a significant impact on aquatic benthic organisms under different treatment conditions. The increase in temperature led to a notable rise in species richness and α-diversity, primarily attributed to the stimulation of metabolic activities in zoobenthos, promoting their growth and reproduction. This finding underscores the potential influence of climate change on aquatic benthic ecosystems, particularly in terms of its promoting effect on α-diversity. However, it is essential to note that elevated temperatures also reduced β-diversity among different sites, implying a potential trend toward homogenization in zoobenthos communities under warmer conditions. Moreover, this study revealed the interactive effects of multiple stressors on the diversity of aquatic benthic communities. Specifically, the pesticide imidacloprid’s impact on zoobenthos is not isolated but demonstrates complex effects within various treatment interactions. In the presence of both temperature elevation and the addition of imidacloprid, the presence of imidacloprid appears to counteract the adverse effects of temperature elevation, resulting in increased species diversity. However, when imidacloprid coincides with nutrient input, it significantly affects α-diversity negatively. These findings highlight the complexity of zoobenthos responses to multiple stressors and how these factors influence both α-diversity and β-diversity. They provide valuable insights for further research on the conservation and management of ecosystems.

Species Diversity of Zooplankton of Small Steppe Lakes of the Northern Part of Kazakhstan

The inland waters of Northern Kazakhstan are important components of the ecosystems of this region and have unique characteristics. Endorheic steppe lakes are important ecosystems with significant ecological value. They play an important role in maintaining biodiversity, they provide water resources for living organisms, they serve as breeding and migration sites for various animal species, and their zooplankton communities have a key role in the trophic web of these waters. Therefore, the purpose of this work is to study the diversity of zooplankton communities in some small steppe lakes in the northern part of Kazakhstan (Pavlodar, Kostanay, North Kazakhstan, and Akmola regions), which have different environmental conditions. Sampling to study the species diversity of zooplankton in the steppe water bodies of Northern Kazakhstan was carried out from 13 areas, 12 of which are plain lakes, and 1 of which is a reservoir, and sampling was performed in 2021 and 2022 during in the spring, summer, and autumn periods. Within the research period of 2021–2022, between 6 and 36 species of zooplankton were found in small steppe lakes. A total of 92 taxa were found. Rotifers (46 taxa) were found to have the richest number of species representatives. Cladocera were represented by 21 taxa, and Copepods by 25 taxa. All studied steppe lakes in the northern part of Kazakhstan are characterized by high specificity in terms of taxonomic composition, since the similarity indices did not exceed 0.632. According to cluster analysis, the studied samples of water bodies are divided into five clusters, in which lakes with a relatively similar taxonomic composition are combined. The halophile species (e.g., Arctodiaptomus salinarus) indicate water salinization. Our results confirm the applicability of the use of zooplankton in assessing water quality and the current ecological state of aquatic ecosystems.

Composition, interaction networks, and nitrogen metabolism patterns of bacterioplankton communities in a grassland type Lake: a case of Hulun Lake, China

The composition of bacterial communities in freshwater ecosystems is influenced by numerous factors including environmental conditions and biological interactions. In grassland inland closed lakes, factors affecting lake ecosystems are either exogenous or endogenous, contributing to the formation of distinct habitats in the surface and bottom waters of the bacterial communities. However, the extent to which environmental factors selectively shape the bacterial communities in aquatic systems remains unclear. Therefore, we sampled the surface, middle, and bottom waters at 13 sampling points in each layer. High-throughput sequencing techniques were employed to examine the spatial heterogeneity of the bacterial community structure during summer in Hulun Lake, the largest grassland-type lake in Inner Mongolia, China, to determine the microbial community dynamics and symbiosis patterns under different habitat conditions. Our results revealed a decrease in the diversity and heterogeneity of the bacterioplankton community, influenced by changes in the environment from exogenous inputs to endogenous releases. Furthermore, this alteration in community structure was concomitant with enhanced co-occurrences among microorganisms in the bottom water layers. This finding suggests that endogenous release promotes heightened symbiotic interactions, thereby facilitating the development of more complex modular structures. Symbiotic networks in different layers were differentiated by key species, with the ecological clustering modules of these species demonstrating dissimilar environmental preferences. The microbial communities were highly habitat-specific, mimicking responses to total nitrogen (TN) in the surface layer, pH in the middle layer, and chemical oxygen demand (COD) in the bottom layer. Bacterioplankton functions were assessed using Tax4Fun, indicating exogenous inputs and endogenous release increased the relative abundance of genes with nitrogen-fixing and nitrification potential nitrogen metabolism functions in surface and bottom waters, respectively. With Planctomycetota and Proteobacteria phyla as potential key groups for regulating nitrogen metabolic processes, Proteobacteria may facilitate the depletion of nitrate in surface and bottom waters, while the close contact of surface waters with the atmosphere accelerated Planctomycetota-dominated nitrogen fixation into the lake. Our findings contribute to the understanding of vertical microbial diversity and its network patterns in grassland type lakes, underscoring the potential role of environmental factors (exogenous inputs and endogenous releases) in bacterioplankton community formation.

A Deep Insight into the Diversity of Microfungal Communities in Arctic and Antarctic Lakes.

We assessed fungal diversity in water and sediment samples obtained from five Arctic lakes in Ny-Ålesund (Svalbard Islands, High Arctic) and five Antarctic lakes on Livingston and Deception Islands (South Shetland Islands), using DNA metabarcoding. A total of 1,639,074 fungal DNA reads were detected and assigned to 5980 ASVs amplicon sequence variants (ASVs), with only 102 (1.7%) that were shared between the two Polar regions. For Arctic lakes, unknown fungal taxa dominated the sequence assemblages, suggesting the dominance of possibly undescribed fungi. The phylum Chytridiomycota was the most represented in the majority of Arctic and Antarctic samples, followed by Rozellomycota, Ascomycota, Basidiomycota, and the less frequent Monoblepharomycota, Aphelidiomycota, Mortierellomycota, Mucoromycota, and Neocallimastigomycota. At the genus level, the most abundant genera included psychrotolerant and cosmopolitan cold-adapted fungi including Alternaria, Cladosporium, Cadophora, Ulvella (Ascomycota), Leucosporidium, Vishniacozyma (Basidiomycota), and Betamyces (Chytridiomycota). The assemblages displayed high diversity and richness. The assigned diversity was composed mainly of taxa recognized as saprophytic fungi, followed by pathogenic and symbiotic fungi.

Effects of Massive Use of Disinfectants on the Plankton Communities in Lakes from Wuhan

The outbreak of COVID-19 led to the extensive use of disinfectants in urban areas. These disinfectants, along with disinfection by-products (DBPs), eventually enter waters and affected the aquatic organisms. But little information could be obtained on disinfectants threatening aquatic ecosystems. This study was conducted to obtain insight into the effects of massive use of disinfectants on freshwater ecosystems, DBPs, phytoplankton, and zooplankton in nine urban and two country lakes in Wuhan during the COVID-19 pandemic; in addition, the residual chlorine in the South Lake (one of the urban lakes), was investigated. The concentration of residual chlorine in the South Lake ranged from 0.000 mg L−1 to 0.427mg L−1, with an average concentration of 0.092 mg L−1. The total concentrations of DBPs (halogenated aliphatic DBPs and aromatic halogenated DBPs) detected in the urban and country lakes ranged from 4.22 μg L−1 to 16.59 μg L−1 and 5.92 μg L−1 to 7.84 μg L−1, respectively. There was no significant difference in DBPs content between urban lakes and country lakes (p < 0.05). Mann–Whitney U tests showed no significant differences in plankton cell density, biomass, and alpha diversity indexes between urban and country lakes, except for the Shannon−Wiener diversity index of phytoplankton. Beta diversity demonstrated that plankton communities at different sampling stations in urban and country lakes were not significantly separated into two groups, but rather intersected each other. Variance partitioning analysis revealed that the composition of plankton communities was primarily influenced by other plankton organisms and community stability under the conditions of the investigated factors. Results indicated that the detected plankton communities in urban lakes from Wuhan were not significantly affected by the use of disinfectants. It could be deduced that the massive use of disinfectants in this outbreak had no significant impact on the plankton communities.

Whole-lake food web model indicates alewife invasion fueled lake trout restoration and altered patterns of trophic flow Lake Champlain

Food web responses to invasion can be context-dependent and therefore difficult to predict based only on invasion histories. Alewives (Alosa pseudoharengus) had generally negative impacts on the native fish communities of the Laurentian Great Lakes after they invaded in the 19th century and were thus expected to negatively impact the Lake Champlain food web after entering the lake in 2003. We evaluated the impact of alewives on the Lake Champlain food web by compiling 25 years of biomass, abundance, and diet data and constructing an Ecopath with Ecosim model of the coldwater food web. Model projections indicated that, contrary to the Great Lakes experience, biomass of native predators increased, mortality rates decreased, and overall trophic level of the pelagic fish community decreased after alewife entered the system. Consequently, the amount of primary production supporting predator biomass increased in response to the addition of prey fish production. The model suggests that alewife invasion in Lake Champlain could have altered food web structure by transferring more energy to tertiary consumers via pelagic pathways at the expense of other energy pathways and “jump started” wild lake trout recruitment by expanding the forage base. In contrast to the Great Lakes response to alewife invasion, Lake Champlain may represent an alternate trajectory for alewife invasion and demonstrates that alewife impacts are context-dependent.