Zoobenthos Communities Research Articles

Current Velocity: a Driving Factor for Structuring Zoobenthos Community in a Fluvial System of Indian Himalaya

Current Velocity: a Driving Factor for Structuring Zoobenthos Community in a Fluvial System of Indian Himalaya

Prospects for fisheries use of lake Sobache (Pionerskoe) in the Republic of Khakassia

We assess Sobache (Pionerskoe) lake located in The Republic of Khakassia for aquaculture using. The lake is drainless, the water-surface area is about 1.5 km2. The prevailing depths range from 2 to 4 m. We provide data on the hydrological regime of the lake (temperature, dissolved oxygen level, chemical water composition). 3 species of rotifers, 10 species of cladoceran and 3 species of copepods were found in the zooplankton. The dominant complex consists of the rotifer Asplanhna priodonta, Bosmina longirostris and Ceriodaphnia quadrangula. The zoobenthos community includes 13 groups of organisms, where chironomids predominate in abundance, and gastropods and bivalves predominate in biomass. The ichthyofauna of the lake consists of perch and pike, perch predominates in abundance. Four species of parasites were found, including trematodes and myxporidia. The infection of fish with trematode metacercariae indicates the presence of intermediate hosts in the zoobenthos community of the lake. The detected species of parasites do not pose a danger to human health. The natural fish productivity is estimated at 48.2 kg/ha. We recommended to use the lake for commercial cultivation of fish in polyculture way. We proposed two schemes of fishery exploitation of the lake on the principle of pasturable fish culture: annual cultivation of fish in polyculture (carp, trout, herbivorous fish species) and joint cultivation of fish in polyculture (carp and white amur) by continuous intensive technology (three-year turnover) with carp feeding. The expected yield of fish products varies from 460.0 to 400.0 kg/ha, depending on the chosen technology. These recommendations can contribute to the effective use of the fisheries potential of Sobache (Pionerskoe) lake to provide the region with fresh fish products and create jobs for the local population.

Water quality shapes the community structure of zoobenthos in rivers but only has a minor effect on the fatty acid composition of zoobenthos and salmonids

AbstractMany river ecosystems in the boreal zone have faced remarkable changes due to intensive human activities, including land‐use changes in the catchments and channelization. Recently, restoration efforts have increased, hoping to restore a more natural hydromorphology. We studied the community structure of benthic macroinvertebrates (zoobenthos) in seven rivers in Eastern Finland, using samples that covered pre‐ and post‐restoration periods, to examine how environmental metrics relate to the zoobenthos community structure, and the fatty acid (FA) composition and content of Ephemeroptera, Plecoptera, and Trichoptera nymphs and larvae. We also analyzed the FA composition and content of land‐locked salmon (Salmo salar m. sebago) in three of the rivers and brown trout (Salmo trutta) in two of the rivers. Zoobenthos communities differed significantly among most of the rivers: 24% of the differences between the zoobenthos communities were driven by water quality parameters related to the loading of terrestrial organic matter (water color, pH, and iron concentration). Temporal changes in zoobenthos communities could not be fully attributed to restorations. The FA composition of zoobenthos was mostly explained by phylogenetic origin (47%). However, especially mayfly Heptagenia sulphurea (Ephemeroptera: Heptageniidae) had variable FA composition and content among the rivers suggesting an environmental quality indicator role for this species. FA composition and content of salmonids were mostly size‐dependent (24%), but river identity also influenced their FA composition (22%). Our results indicate that water quality affects the availability of essential FAs for consumers by altering the zoobenthos community structure and their FA composition and content.

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.

Trophic characteristics of zooplankton and zoobenthos in certain water masses in the western Chukchi Sea, by δ<sup>15</sup>N and δ<sup>13</sup>С data

To compare trophic characteristics for pelagic and bottom communities of zooplankton and zoobenthos in the western Chukchi Sea, isotopic composition of carbon and nitrogen (δ13С and δ15N) is determined for three different types of water masses. The main area of the southwestern part of the sea (to the south of 71оN) is occupied by the surface and subsurface water masses invaded from the Bering Sea with relatively high δ13C and low δ15N values. The cold Arctic waters prevail in the northwestern area. The western periphery of the sea is influenced by the water masses from the East Siberian Sea transported by the alongshore Siberian Current, distinguished by significantly lowered δ13С values and somewhat (by 1–3 ‰) increased δ15N values. A stable difference in the carbon isotopic composition between zooplankton and benthic invertebrates is revealed in the southwestern Chukchi Sea that means that the benthic organisms are based mainly on the bottom food chain, with a minimal input of organic matter from the water column. In the area influenced by the water masses from the East Siberian Sea, benthic invertebrates have the lowest values of δ13С comparable to those of zooplankton that is a sign of organic sediments from the water column utilization, partly terrigenous in origin. The role of primary producers for plankton and benthos in the northwestern Chukchi Sea has not been fully elucidated and requires additional studies. However, the main trophic base for the benthic community is assumed there to be organic matter removed from the water column, originated mainly from ice algae.

Ecological implications of fish removal: Insights from gut-content analysis of roach (Rutilus rutilus) and European perch (Perca fluviatilis) in a eutrophic shallow lake.

Large reductions in fish biomass are common both as a method of managing lake ecosystems by fish removals (biomanipulation) and as naturally occurring fish kills. To further understand how fish reductions change feeding patterns of fish, we studied the diets of small- to medium-sized roach (Rutilus rutilus) and European perch (Perca fluviatilis) on a monthly basis using gut-content analysis during an 18-month period before and after a whole-lake fish removal in a eutrophic shallow lake. Further, we performed in-depth analyses of zoobenthos communities of the profundal and littoral zones, as well as analysed the zooplankton community in the littoral and pelagic parts of the lake to estimate abundance and biomass of potential diet items. We found that, in general, there was a trend toward increased zoobenthivory in both species and among all-sized fish after fish removal, regardless of prior diet preference. Reduced piscivory among larger perch (>150 mm) and reduced zooplanktivory among smaller perch and roach (<150 mm) were also observed. Moreover, during a short period of high zooplankton biomass after fish removal, both perch and roach (all sizes) shifted their diet toward daphnids, which likely caused a decrease in daphnid population. We suggest that such change toward periodical zooplanktivory across fish species and size groups may lead to unexpectedly high top-down control by fish after lake restoration by fish removal.

Temporal variation of plankton and zoobenthos communities in a freshwater reservoir: Structure feature, construction mechanism, associated symbiosis and environmental response

Phytoplankton, zooplankton and zoobenthos, due to their tiny size and high reproductive efficiency, usually hold an essential position in freshwater reservoir biomes. Understanding their community traits and symbiosis mechanism is crucial for determining the nature of water ecological environment and the water ecosystem’s evolution. However, the dynamics of interspecific and environmental interactions, as well as community-building processes, are currently unclear. Here, the structure feature, construction mechanism, associated symbiosis and environmental response of plankton and zoobenthos communities were studied in a freshwater reservoir. The features of phytoplankton, zooplankton, and zoobenthos communities varied significantly by season. Dispersal limitation played an important role in the construction of phytoplankton, zooplankton and zoobenthos communities, and the influence degree decreased in order. Phytoplankton communities showed a stronger distance-decay of similarity than zooplankton communities, while zoobenthos communities did not exhibit any discernible distance-decay of similarity. Co-existence network displayed primarily positive interactions between phytoplankton, zooplankton and zoobenthos all year round (92.23% positive in summer, 86.36% positive in autumn, 100% positive in winter and 67.35% positive in spring). Variation partitioning analyses showed that geographical variables had a stronger influence on community distribution than environmental factors. Mantel test revealed that the communities diversity was significantly associated with temperature, dissolved oxygen, nutrients N and nutrients P. Temperature exhibited the highest explanation rate for seasonal variation in phytoplankton (11.48%, p < 0.001) and zooplankton (16.22%, p < 0.001), according to redundancy analysis. These findings provide a thorough comprehension of the biological communities' dynamic equilibrium in a freshwater reservoir aquatic systems.

Structure of the zoobenthos communities from Dubasari and Kuchurgan reservoir based on the zoogeographic classification

The Dubasari reservoir is located on the river Nistru, while the Kuchurgan reservoir is a lake type and serves as a cooling reservoir for the Moldovan Thermal Power Plant. Reservoir zoobenthos is mainly formed of thermophilous Palearctic species of the Holarctic region (mainly oligochaetes and chironomids), including PontoCaspian relicts (polychaetes, higher crustaceans, and mollusks). There are 18 species of Ponto-Caspian relicts in the Dubasari reservoir and 25 species in the Kuchurgan reservoir. North American and Southeast Asian introduced species in the zoobenthos of the Dubasari reservoir are represented by one species, and in the Kuchurgan reservoir by three species. The most significant commonality (0,74 according to the Sorensen index) and similarity (0,59 according to the Jaccard index) of the species composition of zoobenthos are typical for the Ponto-Caspian fauna of reservoirs.

Environmental quality improvement of a mariculture plant after its conversion into a multi-trophic system

Integrated Multitrophic Aquaculture (IMTA) seems to be one of the best solutions for sustainable aquaculture. Within the Remedia LIFE Project, an experimental IMTA plant was put in place in the Mar Grande of Taranto (Mediterranean Sea, Southern Italy). The polyculture of several bioremediating organisms, such as mussels, tubeworms, sponges, and seaweeds, was combined with a coastal cage fish farm, in order to remove organic and inorganic wastes coming from the fish’s metabolism. To verify the effectiveness of the system, the ex ante measurement of chemical-physical variables, trophic status, microbial contamination, and zoobenthos community health was compared with the results of the same measurement performed one year and two years after the implementation of the experimental IMTA plant. The results were encouraging, since a reduction in total nitrogen concentration in the seawater (from 43.4 ± 8.9 to 5.6 ± 3.7 μM/l), a reduction in microbial pollution indicators in the seawater (total coliforms: from 280 ± 18 MPN/100 mL to 0; E. coli: from 33 ± 1.3 MPN/100 mL to 0) and in the sediments (total coliforms: from 230 ± 6.2 MPN/100 g to 170 ± 9; E. coli: from 40 ± 9.4 MPN/100 g to 0), an enhancement of the trophic status (TRIX: from 4.45 ± 1.29 to 3.84 ± 0.18), and an increase in the zoobenthic quality indices and biodiversity were recorded (AMBI: from 4.8 to 2.4; M-AMBI: from 0.14 to 0.7). These results prove that the Remedia LIFE project's purpose was achieved. The selected bioremediators worked synergistically, improving water and sediments quality within the fish farm area. Moreover, bioremediating organisms increased their weight as a result of wastes uptake, producing, as co-products, large amounts of additional biomass. This could be commercially exploited, thus being an added value of the IMTA plant. Based on our findings, the promotion of eco-friendly practices to ameliorate ecosystem health should be encouraged.

Present State of Zoobenthos in Small Reservoirs of Nothern Slope Baltic-Caspian Watershid of Volgo-Baltic Water Way

In 2010–2013 first investigation of benthic fauna in Novinkinskiy, Belousovskiy and Vytegorskiy water reservoirs were carried out. Totally 103 species of zoobenthos were found. Increase of abundance, species richness and diversity in range profundal–open littoral–thicket littoral was recorded. In profundal of all reservoirs was found complex of species Limnodrilus hoffmeisteri – Procladius. In littoral structure of zoobenthos communities depended from type of substrate and thicket species. Maximum abundance of zoobenthos was recorded in anomaly hot 2010. In comparison with located to the south Volga reservoirs, Novinkinskiy, Belousovskiy Vytegorskiy reservoirs characterized low abundance and species richness.

Temporal Variation of Plankton and Zoobenthos Communities in a Freshwater Reservoir: Structure Feature, Construction Mechanism, Associated Symbiosis and Environmental Response

Temporal Variation of Plankton and Zoobenthos Communities in a Freshwater Reservoir: Structure Feature, Construction Mechanism, Associated Symbiosis and Environmental Response

Long-Term Variations in Zoobenthos Characteristics in Watercourses on the the Khektsir Ridge

The results of long-term studies are used to present, for the first time, the structural organization of zoobenthos communities and the dynamics of their density and biomass in rivers and brooks of the the Khektsir Ridge, including the boundaries of the Bol’shekhekhtsirskii Reserve, Khektsirskii Wildlife Reserve (the southern part of the Russian Far East). The benthic organisms were found to contain 23 groups (22 groups in the spring and summer, 19 groups in the autumn, and 8 groups in the winter). Leading in the occurrence frequency (90%) were chironomids, mayflies, and oligochaetes. The chironomids and amphipods accounted for 37.0 and 19.1% of the total benthos density, and mollusks and amphipods, for 32.1 and 29.7% of the total biomass, respectively. Dominants in terms of density and biomass were amphipods; chironomids dominated in terms of density, and mollusks, in terms of biomass. The mean density of benthic organisms was 637 ± 21 spec./m2, and the mean biomass was 1.8 ± 0.2 g/m2. The benthic communities of rift segments in the rithral zone were found to be most productive. It is shown that the seasonal and long-term dynamics of zoobenthos communities is pronounced and can be traced in the group composition, structure, and quantitative characteristics.

Body size as key trait determining aquatic metacommunity assemblies in benthonic and planktonic habitats of Dongting Lake, China

• Aquatic community diversity decreased with increasing body size. • Body size affected distance-decay relationship of benthonic communities. • Higher effects of body size on benthonic community assembly than planktonic one. • Biotic interactions between microbial species were mediated by their body sizes. Body size play a key role in driving bioecological patterns by affecting community assembly processes at the organism level. However, the extent to which the relative influences of ecological processes operating community assembly with different body sizes at different habitat types in freshwater ecosystem is still unclear. Here, we conducted a comprehensive biodiversity survey on bacterial, fungal and invertebrate communities in planktonic and benthonic habitats of Dongting Lake, China, and evaluated the biogeographic distribution pattern and community assembly processes of distinct organism groups with different body sizes. Significant negative relationships between body size and community diversity indexes were observed in two habitats, and significant relationship between body size and distance-decay relationship was only observed in benthonic habitat. Body size showed stronger correlations with the ecological processes and ecological interactions of distinct organisms in benthonic habitat. Specifically, body size showed significantly positive correlation with the relative influence of deterministic processes which controlled the microbial community assembly processes, whereas body size was significantly positively correlated with stochastic processes in zoobenthos community. Molecular ecological network analyses also found that the average clustering coefficients and among-module connectivity were significantly negatively and positively correlated with their corresponding body size, respectively. Slops of correlations between body size and these parameters (including the null deviation value, dispersal rate, niche breadth and among-module connectivity) were steeper in benthonic habitat than that in planktonic habitat. Our findings suggested that body size operated the aquatic organism community assembly to affect their biogeographic distribution pattern, and the effect was stronger in benthonic habitat than in planktonic habitat. This study provides a better understanding of the mechanisms supporting the aquatic biodiversity on the sight of organism life-history trait.

ГИДРОДИНАМИЧЕСКИЕ ФАКТОРЫ ФОРМИРОВАНИЯ И ФУНКЦИОНИРОВАНИЯ ГИДРОБИОЛОГИЧЕСКИХ СООБЩЕСТВ НА ПРИМЕРЕ ЗООБЕНТОСА КУРШСКОГО ЗАЛИВА

The influence of hydrodynamic factors on the formation of zoobenthos communities in the coastal zone exposed to active wind-wave mixing, as well as in the deep part of water bodies characterized by the silt accumulation is considered for the Curonian Lagoon. The features of the qualitative and quantitative distribution of zoobenthos and their effect on determining the water quality using zoobenthos parameters are analyzed. Recommendations are given for the placement of hydrobiological monitoring stations based on zoobenthos parameters.

Current information about zoobenthos and assessment of the ecological state of the Boguchany reservoir

The regulation of river flow entails a change in the habitat of aquatic organisms. Biological communities can vary and be formed over several years, that is why it is necessary to monitor the state of reservoir ecosystems regularly. Currently, there is a significant gap in modern studies of the benthic fauna of the Boguchany reservoir, which is the lower stage of the Angarsk hydro-electric power station cascade. During five years (2014–2015, 2017–2019), zoobenthos communities had been studied in the lower part of the Boguchany reservoir. The benthic fauna was chironomid-gammarid in nature with a predominance of chironomids. 75 species of invertebrates were identified, 39 of them belong to dipterous insects of the Chironomidae family. The shallow water communities are qualitatively and quantitatively much richer than in the deep water zone. With a decrease in depth, there was an increase in the number of invertebrates by about 6 times due to the small-sized species of chironomids. The number of zoobenthos in the deep water zone was 0.3 thousand ind./m2, in the shallow water — 1.8 thousand ind./m2. The biomass in different deep zones did not differ significantly: in the deep part — 2.0 g/m2, in shallow water — 2.4 g/m2. The trophic status of the Boguchany reservoir in 2018 corresponded to the mesotrophic type of medium food capacity (III class), in other years — to the oligotrophic type of low food capacity (II class). Nowadays, the formation of bottom fauna is at the stage of biocenosis stabilization. An integrated approach of three bioindicative indicators (Mayer, saprobity and Shannon indices) was used to assess water quality according to bottom communities. The fundamental criterion for the selection of indices was the consideration of the benthocenosis structural organization, i.e. the development degree of indicator taxa.Water quality, assessed by the state of zoobenthos communities, corresponded to III class, “Moderately polluted”, β-mesosaprobic zone

Біотичні особливості використання Київського водосховища як рибогосподарського водного обʾєкта (Огляд)

Purpose. To analyze the range of special scientific literature and summarize the information obtained on the modern biotic features of the Kуiv reservoir. Namely: the state and specificity of communities of phytoplankton, zooplankton, zoobenthos and macrophytes from this reservoir. To consider the main data on their formation, as well as the direction of further development and impact on fish productivity. Findings. An overview of scientific publications devoted to the biotic features of the Kуiv reservoir, which directly affect its potential as a fishery water body, were presented. The literature data on the most widespread communities of phytoplankton, zooplankton, zoobenthos, and macrophytes in this reservoir are generalized. The main directions in which they affect the possibility of commercial fisheries in this reservoir are described. The general aspects of the anthropogenic pressure impact on them, as well as their consequences, are considered. The perspective ways of further development of the Kyiv reservoir as a fishery water body with the systematic implementation of complex reclamation measures and the organization of rational commercial fishing are shown. Practical Value. The review may be useful for scientists, Ph.D. students, students, government authorities, and private entrepreneurs involved in the research process or exploitation of aquatic living resources in internal water bodies, primarily in the Kуiv reservoir. Keywords: Kуiv reservoir, fishery water body, biota, phytoplankton, zooplankton, zoobenthos, macrophytes.

Composition and structure of benhtic macroinvertebrate communities in watercourses of Donji Vakuf

Zoobenthos are one of the most significant communities in aquatic habitats. Remediation of aquatic ecosystems depends on maintaining a healthy zoobenthos community. The first step in restoring aquatic ecosystems is to understand the hydrology and water quality parameters that influence zoobenthos variation. Based on field sampling of the river zoobenthos in the watercourses of Donji Vakuf, the current study used principal component analysis to identify the key habitat elements affecting zoobenthic communities. Bray-Curtis similarity was used to compare analyzed zoobenthic communities. The findings in this study demonstrate that water temperature, dissolved oxygen, total Phosphourous and total Nitrogen were the main physical and chemical water quality parameters affecting the zoobenthic populations in investegated watercourses. The highest similarity of analyzed macrozoobenthos communities was observed between Semešnica river and Sokolinski stream. All of the approaches described in this work can be used for studies on different communities, such as fish, algae, and zooplankton in aquatic ecosystems. Managers can use the techniques and findings in this report as important references to safeguard and revitalize deteriorated water ecosystems.

基于环境DNA宏条形码技术的秦淮河生物多样性研究

秦淮河是南京的母亲河, 其生物多样性受城市化进程影响面临严重威胁, 而物种资源调研是生物多样性保护的基础。环境DNA宏条形码技术较形态学监测是一种简单高效、灵敏度高的新型监测技术。为探究秦淮河浮游生物、底栖动物及鱼类的生物多样性, 于2019年7月, 采用环境DNA宏条形码技术对其进行了探究, 并分析了秦淮河上下游间的差异及环境因子对其群落结构的影响。结果表明: 秦淮河共监测到浮游动物13属22种407个操作分类单元(Operational Taxonomic Units, OTUs), 浮游植物85属60种4445个OTUs, 底栖动物16属17种212个OTUs, 鱼类53属44种1663个OTUs。其中浮游动物以游泳轮虫目(Ploima)和双甲目(Diplostraca)为主, 共占浮游动物63.37%, 浮游植物以隐藻门(Cryptomonas)和褐藻门(Ochrophyta)为主, 共占浮游植物88.11%, 底栖动物中节肢动物门(Arthropoda)占比最高, 达91.67%, 鱼类中鲤形目(Cypriniformes)占比最高, 达69.99%。与秦淮河历史形态学监测数据相比, 环境DNA宏条形码技术在物种丰度鉴定方面显著高于传统形态学鉴定的物种丰度。通过主坐标分析和PERMANOVA检验, 发现秦淮河下游、上游南支和上游北支间有极显著差异(P < 0.001)。其中浮游动物、浮游植物和底栖动物受分组影响更大, 分组对鱼类的影响相对较小。下游α多样性较上游更为贫乏, 上游南支(南京)α多样性较上游北支(句容)更丰富。浮游生物和底栖动物均表现出了明显的随距离增加而衰减的趋势。冗余分析表明, 较低营养级的生物对环境因子的变化更为敏感, 浮游生物和底栖动物的主要影响因子为总氮、总有机碳、总磷、氨氮、化学需氧量和溶解氧。鱼类的影响因子为溶解氧、总有机碳、总氮、总磷和化学需氧量。研究通过对秦淮河生物多样性的调研, 可为秦淮河的生物多样性保护提供理论参考。;Qinhuai River is the mother river of Nanjing, and its biodiversity is seriously threatened by the process of urbanization. The survey of species resources is the basis of biodiversity protection. Compared with morphological monitoring, the environmental DNA metabacroding is a simple, efficient and sensitive new monitoring technology. In order to explore the biodiversity of plankton, zoobenthos and fish in Qinhuai River, the environmental DNA metabacroding was used to explore it in July 2019, the differences between upstream and downstream of Qinhuai River were analyzed, and the relationship between the community composition of Qinhuai River and environmental variables was evaluated. The results showed that a total of 13 genus, 22 species and 407 operational taxonomic units (OTUs) of zooplankton, 85 gennus, 60 species and 4445 OTUs of phytoplankton, 16 genus, 17 species and 212 OTUs of zoobenthos, 53 genus, 44 species and 1663 OTUs were detected through the environmental DNA metabacroding. Among them, Ploima and Diplostraca, accounting for 63.37%, were dominant species in zooplankton community at the order level. The most abundant species in phytoplankton community at the phylum level were Cryptomonas and Ochrophyta, accounting for 88.11%. The zoobenthos were dominated by Arthropoda at the phylum level, which accounted for 91.67%. The Cypriniformes accounting for 69.99%, were dominants in fish of different samples at the order level. Compared with the historically morphological monitoring data of Qinhuai River, the environmental DNA metabarcoding technique was more powerful than the morphological method in assessment of species richness. Through the principal coordinate analysis (PCoA) and PERMANOVA test, a significant difference (P < 0.001) was found among downstream, the south branch of upstream and the north branch of upstream of Qinhuai River. Zooplankton, phytoplankton and zoobenthos were more affected by the group of sites than fish. Alpha(α) diversity of downstream in Qinhuai River was poorer than that of upstream, and Alpha(α) diversity of the south branch of upstream (Nanjing) was richer than that of the north branch (Jurong). All of the taxa of Qinhuai River except fish showed strong relationship between geographical distance (km) and biotic community similarity based on Bray-Curtis distance. Redundancy analysis (RDA) showed that organisms with lower trophic levels were more sensitive to changes in the environmental factors. The main influencing factors in plankton and zoobenthos community distribution were total nitrogen (TN), total organic carbon (TOC), total phosphorus (TP), ammonia nitrogen (NH₃-N), chemical oxygen demand (COD) and dissolved oxygen (DO). While the key factors in fish community distribution were DO, TOC, TN, TP and COD. Our results can provide a theoretical reference for the protection of the biodiversity of Qinhuai River.

Species diversity of planktonic and zoobenthic communities of floodplain lakes in the middle reaches of the Irtysh river in the Omsk region

Based on hydrobiological studies conducted within the boundaries of the Omsk region, the species diversity of zooplankton and zoobenthic communities of floodplain lakes in the middle reaches of the Irtysh River is presented. The characteristics of zooplanktonic and zoobenthic invertebrates by qualitative and quantitative indicators are considered. The assessment of lakes by trophic and feeding capacity of reservoirs is given. The species diversity of the zooplankton and zoobenthic communities is shown. Zooplankton includes organisms of 20 genera from 11 families. The total number of species is 26, of which 12 are rotifers from two orders belonging to 5 families. Eleven species of branchiform crustaceans belonging to 10 genera from 4 families and three species of copepods belonging to 2 orders. It was found that the greatest species diversity was observed in the lake without the name of the Lubinsky district — 19, the smallest in such lakes as Staritsa, Peschanoe, and without the name of the Tavrichesky district — 12 taxa. The average abundance and biomass for the studied reservoirs was 75.9 thousand copies/m³ and 574.61 mg/m³, respectively. According to the average indicators of zooplankton biomass, floodplain lakes are characterized as ultra-oligotrophic reservoirs of the lowest productivity class. Zoobenthos community of floodplain lakes in the middle reaches of the river the Irtysh of the Omsk region, during the research period, is represented by 25 taxa belonging to three classes of organisms: insects( Insecta), leeches (Hirudinea) and small-scale worms (Oligochaeta). The larvae of chironomids (Sigopominae), mayflies (Ephemeroptera) and small-scale worms (Oligochaeta) formed the basis of the abundance and biomass. The average number of zoobenthos in floodplain lakes of the Omsk region during the study period was 465 specimens/m². The average biomass was 1.519 g/m². According to the average indicators of the biomass of the zoobenthos community, the floodplain lakes of the Omsk region belong to low-feed reservoirs, according to the trophic status — to the oligotrophic type of the low class.

Zoobenthos community turnover in a 1650‐yr lake‐sediment record of climate‐driven hydrological change

AbstractIn fluctuating lake ecosystems, the severity of anthropogenic disturbance is often difficult to assess because the magnitude of natural dynamics rivals or surpasses that of ecosystem alteration due to human impact. Consequently, it is also difficult to evaluate the resilience of these ecosystems' plant and animal communities to that impact. Unfortunately, lake ecosystem response to natural cycles of lake‐level and salinity fluctuation at multi‐annual time scales is poorly understood, due to complex relationships between hydrological dynamics and the local availability or distribution of ecological niches. We present a 1650‐yr‐long paleoecological record from Lake Naivasha in Kenya (East Africa) which traces community assembly and turnover in two prominent groups of benthic invertebrates (chironomids and ostracods) in response to a climate‐driven sequence of 10 major lake‐level fluctuations. Over this time period, lake depth (inferred from sedimentology) fluctuated between ~3 and &gt;35 m, and salinity (inferred from fossil diatom assemblages) varied between ~100 and ~23,500 µS/cm. Prior to ~780 yr ago, the unique community response to salinity was stronger than to lake depth. Around that time the lake transitioned to a more open hydrology, relatively stable freshwater conditions and greater prevalence of macrophyte‐associated benthic habitat, so that community response to variations in lake depth (and surface area) became stronger. Notably, major community restructuring in the course of this transition was not synchronous between the two groups, because it depended on the proliferation of key freshwater species in each group. Our results imply that (1) climate‐sensitive lake ecosystems are more likely controlled by salinity change if both its amplitude and frequency are large enough to induce ecological species sorting; (2) community response to such salinity changes may be predictable, and likely to show coherence across different groups of aquatic biota; and (3) the timing of major community restructuring strongly depends on the ecology of key species, and whether the species sorting is driven by salinity change itself or indirectly by the salinity‐dependent availability of ecological niches.