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Benthic macroinvertebrate abundance and taxa richness associated with environmental variables were monitored monthly from September 2015 to August 2016 in the Nyamuhinga River. The benthic macroinvertebrate samples were collected using a D-frame aquatic net employing the man-time method. Environmental variables including pH, temperature, conductivity, and total dissolved solids (TDS) were measured using a Combo HI 98129 and GREISIN-GER 020 multimeters, and water flow was assessed using the Float Method procedure. The Shannon-Wiener and equitability indices were then calculated to assess diversity and richness, facilitating the comparison of diversity within sites or stations. A total of 35,142 macroinvertebrate individuals were collected from the 12 sampling sites belonging to 29 genera, 27 families, and 9 orders. Diptera were the most abundant (71.83%) followed by Odonata (9.13%) and Ephemeroptera (7.11%). The findings showed that taxa richness decreased from upstream to downstream. At the same time, absolute abundance increased from downstream to upstream due to riparian vegetation, substrate type, plant debris, and organic matter which are habitats for benthic macroinvertebrates in the river. Environmental variables such as flow, pH, temperature, conductivity, and TDS varied between sites and stations because of habitat disturbances, contaminant discharges into the catchment, and inflow of tributary waters into the river. The canonical correspondence analysis (CCA) results displayed that Eristalis and Chironomus were strongly associated with the flow, conductivity, TDS, temperature, and pH at the downstream sites related to anthropogenic activities from the catchment. From our results, the Nyamuhinga River needs conservation master plan/guidelines and increased awareness to reduce environmental impacts in Bukavu River catchments in the Lake Kivu basin.

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The northwestern shelf of the Black Sea has been affected by eutrophication and bottom hypoxia since the sixties. Consequently, the macrozoobenthos has suffered a well-established decline in biodiversity. However, the nature of the current benthic communities remains questionable. From 1995 to 2017, we compiled species and abiotic data for 138 sites over the shelf. Through an appropriate multivariate analytical approach, we identified benthic community changes solely due to organic pollution variations. Our results show signs of recovery with an increase in biodiversity and proportion of species vulnerable to organic enrichment. These changes were related to a decrease in riverine loads and subsequent eutrophication. However, some long-lived species typical of the area still did not exhibit noticeable recovery, which suggests that either the recovery process has not yet been achieved or some environmental conditions are still not met to warrant a sea floor ecosystem state substantially healthy.

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Protecting rivers and lakes from pollution is crucial for maintaining the health of aquatic ecosystems and ensuring the well-being of both wildlife and humans. Present study intends to examine the water quality of the Suna River (Eastern Fennoscandia in the European North of Russia) to assess the ecological risk. Widespread methods for assessing water quality based on macrozoobenthos and phytoperiphoton were applied. It was found that in conditions of ultra-fresh waters with high humus content, biotic indicators may indicate pollution of water bodies that do not actually experience significant anthropogenic impact. Ratings ranging from 'poor' to 'excellent' were obtained for different stations, reflecting the influence of natural features of different sections of the river. 'Good' water quality was noted at the river stones biotopes. In river gravel, sand and silt biotopes, as well as all lake biotopes, 'mediocre' water quality was found. The low anthropogenic income on the river catchment allows us to conclude that most indices for assessing water quality significantly underestimate the results in the natural conditions of Eastern Fennoscandia. Biotic indices EPT, BBI and EBI are most accurate for assessing the water quality of rivers and lakes in Eastern Fennoscandia.

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The response of benthic habitats and organisms to bottom-contact fishing intensity is investigated in marine protected areas (MPAs) of the German EEZ in the North and Baltic Seas. We examined the current state of macrofauna biodiversity in 2020-2022. Comparative analysis for macrofauna (in- and epifauna) inhabiting nine Natura 2000 MPAs constitutes a baseline to assess the effects of bottom-contact fishing exclusion in the future. Aspects of spatial and temporal variability are briefly summarized and discussed. We provide a species list for each region, including 481 taxa, of which 79 were found in both regions, 183 only in the North Sea, and 219 only in the Baltic Sea. The Baltic Sea dataset surprisingly included higher numbers of taxa and revealed more Red List species. The share of major taxonomic groups (polychaetes, bivalves and amphipods) in species richness showed peculiar commonalities between the two regions. In the North Sea, multivariate analysis of community structure revealed significantly higher within-similarity and stronger separation between the considered MPAs compared to the Baltic MPAs. Salinity, temperature and sediment fractions of sand were responsible for over 60% of the variation in the North Sea macrofauna occurrence data. Salinity, mud fraction and bottom-contact fishing were the most important drivers in the Baltic Sea and, together with other considered environmental drivers, were responsible for 53% of the variation. This study identifies aspects of macrofauna occurrence that may be used to assess (causes of) future changes.

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The continental shelf of the northeastern Barents Sea is presently experiencing a weak influx of Atlantic water from the west. In recent times, warming in Arctic regions has led to an increase in extended ice-free periods in this area, instead of significantly elevating water temperatures. The implications of this phenomenon on the structure and functioning of benthic communities were investigated during the autumn of 2019 within the Makarov Strait, located in the southwestern part of the St. Anna Trough. The macrozoobenthic communities exhibited a clear connection with the duration of ice-free periods. This variable influenced a vertical carbon flux, which subsequently served as the primary predictor for faunal abundance and diversity, as demonstrated by redundancy and correlation analyses. Two faunal groups were identified, corresponding to short and long open-water periods. Both groups had similar alpha diversity (65 ± 6 and 61 ± 9 species per station) and biomasses (39 ± 13 and 47 ± 13 g m-2) but displayed differing abundances (1140 ± 100 vs. 4070 ± 790 ind. m-2) and other diversity indices. We observed a decline in the proportion of polychaetes, accompanied by an increase in the proportion and diversity of bivalves, as well as a rise in the abundance of infaunal species, sub-surface deposit feeders, and mobile suspension feeders, in response to the increasing vertical carbon flux. The potential increase in anthropogenic pressures related to oil development in the northeastern Barents Sea highlights the importance of our study for conservation and monitoring efforts in the region.

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Many studies show that habitat complexity or habitat diversity plays a major role in biodiversity throughout different spatial scales: as structural heterogeneity increases, so does the number of available (micro-) habitats for the potential species inventory. The capability of housing species (even rare species) increases rapidly with increasing habitat heterogeneity. However, habitat complexity is not easy to measure in marine sublittoral sediments. In our study, we came up with a proposal to estimate sublittoral benthic habitat complexity using standard underwater video techniques. This tool was subsequently used to investigate the effect of habitat complexity on species richness in comparison to other environmental parameters in a marine protected area situated in the Fehmarn Belt, a narrow strait in the southwestern Baltic Sea. Our results show that species richness is significantly higher in heterogeneous substrates throughout all considered sediment types. Congruently, the presence of rare species increases with structural complexity. Our findings highlight the importance of the availability of microhabitats for benthic biodiversity as well as of the study area for regional ecosystem functioning.

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Climate warming can lead to a replacement of species that favour cold temperatures by species that favour warm temperatures. However, the implications of such thermic shifts for the functioning of ecosystems remain poorly understood. Here, we used stream macroinvertebrate biological and ecological traits to quantify the relative contribution of cold, intermediate and warm temperature-adapted taxa to changes in community functional diversity (FD) using a dataset of 3781 samples collected in Central Europe over 25 years, from 1990 to 2014. Our analyses indicated that functional diversity of stream macroinvertebrate communities increased over the study period. This gain was driven by a net 39 % increase in the richness of taxa that favour intermediate temperatures, which comprise the highest share in the community, and to a 97 % increase in the richness of taxa that favour warm temperatures. These warm temperature-adapted taxa displayed a distinct and more diverse suite of functional traits compared to the cold temperature-adapted group and thus contributed disproportionately to local FD on a per-taxon basis. At the same time, taxonomic beta-diversity declined significantly within each thermal group, in association with increasing local taxon richness. This study shows that over recent decades, small low-mountain streams in Central Europe have experienced a process of thermophilization and increasing functional diversity at local scales. However, a progressive homogenisation occurred at the regional scale, with communities converging towards similar taxonomic composition. As the reported increase in local functional diversity can be attributed mostly to the intermediate temperature-adapted taxa and a few expanding warm temperature-adapted taxa, these patterns could mask more subtle loss of sensitive cold temperature-adapted taxa with irreplaceable functional traits. In light of increasing climate warming, preservation of cold habitat refuges, should be considered a priority in river conservation.

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Macrozoobenthos plays a key role in the transformation of inputs from rivers to the sea, such as nutrients, organic matter, or pollutants, and influences biogeochemical processes in the sediments through bioturbation and bioirrigation activity. The purpose of our study was to determine the structure of benthic communities, their bioturbation (BPC) and bioirrigation potential (IPC), and the vertical distribution of macrofauna in the Gulf of Gdansk. The study revealed changes in the structure of benthic communities and, consequently, in the bioturbation and bioirrigation potential in the study area. Despite the presence of diverse and rich communities in the coastal zone, BPC and IPC values, although high, were formed by a few species. Both indices were formed mainly by the clam Macoma balthica and polychaetes, although the proportion of polychaetes in IPC was higher than in BPC. In the deepest zones, the communities became poorer until they eventually disappeared, along with all macrofaunal functions. Both indices changed similarly with distance from the Vistula River mouth, and there was a very strong correlation between them. We also demonstrated that the highest diversity of the macrofauna was observed in the upper first cm of the sediment, but the highest biomass was observed in deeper layers-at a depth of up to 6 cm, and single individuals occurred even below 10 cm.

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Background: The Mekong River is the 10th largest river in the world. It is recognised as the most productive river in Southeast Asia and economically essential to the region, with an estimated 60-65 million people living in the lower Mekong Basin. The Mekong Delta within Vietnam is considered a highly vulnerable ecosystem under threat from increasing anthropogenic pressure, such as dam construction and, as a consequence, the Delta is sinking and altering the natural hydrological cycle. Dams also lead to eutrophication and pollution of downstream water from regulated water flux and water stagnation. Another threat is climate change coupled with the lower rainfall, which could lead to an increased risk of drought in the Mekong Delta Basin. Thus, these project data represent an important baseline reference. The ecological health of the Mekong Delta's environment, as indicated by the quality and availability of its water and biological resources, largely determines the economic and social development of the region, which produces about half of the agriculture and aquaculture products of Vietnam. New information: This paper reports quantitative data on the biodiversity of six groups of aquatic organisms: bottom and pelagic fish, macrozoobenthos, microorganisms, phyto- and zooplankton in the Mekong Delta within Vietnam, as well as data on the physicochemical parameters of water and bottom sediments. The data were collected during 2018-2022 as part of the Ecolan E-3.4 programme within the framework of the research plan of the Joint Russian-Vietnamese Tropical Research and Technological Center. All presented datasets are published for the first time.

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Changes in species composition and relative abundance caused by pollution might have an impact on the community dynamics and ecosystem functioning. Macrobenthos are widely used as indicators of marine environmental health due to their sensitive to disturbance. The present study aims to evaluate spatial and temporal variability of functional diversity of macrobenthos of the Montevideo and Canelones coastal zone along a pre-established pollution gradient, based on Biological Traits Analysis, and functional diversity indices. Body-size", "Feeding-mode", "Habitat", and "Indicator-role" were useful proxies to detect changes in environmental conditions in organically enriched habitats. FRic, FEve and FDis detected temporal variations but only FRic registered spatial variations. Differences among surveys would mainly reflect environmental variability caused by the 2009-2010 El Niño-Southern Oscillation event. Finally, negative correlations between FEve and FDis with AMBI suggest both indices as useful proxies of benthic environmental health, with potential to be used in monitoring and quality assessment programs.

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Biotic resistance is considered an important driver in the establishment of non-indigenous species (NIS), but experiments in the marine environment have led to contradictory results. In this context, a transplant experiment of fouling communities was carried out over five months. Settlement panels were moved from low impact (species-rich native communities) to high impact sites by NIS in two Italian areas to test the biotic resistance hypothesis. Fouling communities displayed significant differences among treatments before and after the transplant, thus indicating the maintenance of a peculiar fouling community in transplanted panels. On the other hand, newly recruited species were similar between treatments and neither a facilitation nor a mitigation role from native fouling communities on NIS was observed. Our results highlight the importance to better investigate the factors affecting the high variability obtained in experiments testing this hypothesis, with the aim to identify potential solutions for NIS management in ports.

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Fine-grained sediments are a natural component of river systems. Human activities generate additional sources of fine sediment. In mountainous areas, the anthropogenic inputs of fine sediments are associated with forestry. The aim of this study was to analyse the differences in the macroinvertebrate communities between the reference and caused by forest harvesting activities increased influx of fine-sediment to mountain streams. The tested hypothesis was that the macroinvertebrate communities will differ depending on the intensity of forest harvesting practices in the stream catchment that causes excessive influx of fine sediment into the stream. The reintroduction of beavers in the study area, and the formation of in-stream beaver dams, contribute the accumulation of sediments in stream sections with slower water. Thus, it was also assumed that by capturing and storing fine sediments, may contribute to the restoration of the natural structure of the benthic communities downstream of the ponds. The study was carried out in a mountain stream catchment area (Carpathians, Poland), in which inflow of fine sediments in the stream sections varied in intensity. The study was conducted over three years (2018-2020). The extensive use of forest roads, timber skidding trails, and timber storage areas produced fine sediments that clogged the interstitial spaces between the stones in the riffles, limiting the presence of rheophilic taxa associated with coarse-grained substrates. The reduction of the number of scrapers and shredders (i.e. primary consumers) associated with the influx of fine sediments may significantly affect the entire food-web structure in stream ecosystems. The capture and deposition of fine sediments in beaver ponds may accelerate the revitalisation of the flowing sections of the stream. Beaver-induced sediment management is strongly recommended as a beneficial practice that could contribute to ecological preservation and the potential of streams, particularly in mountain areas.

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Macrozoobenthos and submerged macrophytes interact closely. However, studies in China have focused on the middle and lower reaches of the Yangtze River, where shallow lakes are concentrated, rather than on temperate lakes. To clarify the responses of taxonomic and functional groups of macrozoobenthos in temperate lakes to changes in submerged macrophyte biomass (BMac) on a large scale, 19 temperate lakes within Baiyangdian Lake were investigated in this study. The BMac differed greatly across the 19 lakes, and Potamogeton crispus was the dominant species. According to the BMac, the 19 lakes were divided into 4 groups. One-way analysis of variance and Pearson correlation analysis showed that the water environmental parameters were different among the 4 groups, and the BMac was significant correlated with all the physical and chemical parameters of water bodies (except for water depth). Forty-one taxa of macrozoobenthos were identified in the 19 lakes, with oligochaetes, Hirudinea, gastropods, crustaceans, chironomid larvae, and aquatic insects (excluding chironomid larvae) represented by 9, 1, 4, 2, 19, and 6 species, respectively. Chironomid larvae and oligochaetes dominated by density, and gastropods and chironomid larvae dominated by biomass. Canonical correspondence analysis showed that the BMac was the most important factor affecting the macrozoobenthos community structure in group 1 to group 4. Macrozoobenthos with low pollution tolerance values were mainly found in areas with high BMac, while species with high pollution tolerance values were mainly distributed in areas with low BMac and high nutrient contents. Different taxonomic and functional groups of macrozoobenthos responded differently to changes in BMac. As BMac increased, density and biomass of oligochaetes and chironomid larvae tended to decrease, while those of gastropods and aquatic insects tended to first decrease and then increase. Collectors had more species than any other functional group in group 1 to group 4. As BMac increased, density and biomass of collectors gradually decreased, while density of predators, shredders, and scrapers tended to first decrease and then increase.

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Most publications on the influence of environmental factors on macroinvertebrate communities focus on large rivers, whereas relatively few examine small watercourses in agricultural areas, which, due to their size and pressure from intensive agricultural production, are much more susceptible to the effects of unfavourable environmental conditions or anthropopressure. The aim of our study was to compare the biodiversity of macrozoobenthos assemblages and to determine the effects of physicochemical and hydrological conditions on their abundance and density in 10 small rivers in agricultural areas located in northwest (53°23' N 15°14' E) and central (52°11' N 20°48' E) Poland. In total, 105 taxa were recorded, with the majority being euryoecious. Among the assessed physicochemical parameters, oxygenation was found to affect the density and number of taxa; another important factor was the content of nitrate nitrogen. Sensitivity to changes in water temperature was observed in some macrozoobenthos taxa (especially Decapoda). Of the examined hydrological parameters, the greatest effects were exerted by speed, flow, and depth.

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Long-term retention and accumulation of heavy metals in surface water and sediment pose a great threat to the sustainable development of aquatic ecosystems and human health. In this research, macrozoobenthos, and surface water and sediment heavy metal (Mn, Cr, Cu, Ni, Pb, Zn, Cd, and As) samples were collected from 23 sites in the upper and middle reaches of the Heihe River in the summers of 2019-2020. The interrelationships between heavy metals and macrozoobenthos were analyzed by Pearson correlation analysis and redundancy analysis (RDA), and the contamination level and potential ecological risk of the heavy metals in surface water and sediments were assessed by comprehensive pollution index (WQI), single potential ecological risk index ([Formula: see text]), and sediment quality guideline-quotient (SQG-Q), respectively. The results showed that the level of heavy metal pollution in the surface water of the Heihe River was extremely low, but the contents of Mn and Pb exceeded the third class of surface water environmental quality standards (GB 3838-2002). The spatial distribution of heavy metals in surface sediments were significantly different, and the average concentration of 8 heavy metals exceeded the background values of Gansu Province. Meanwhile, the pollution level of heavy metals in surface sediments was high pollution, and the ecological risk level was moderate risk. Combining [Formula: see text] and SQG-Q evaluations showed that Cd, Ni, and Cr were the main ecological risk factors. In addition, the distribution coefficients of Cr and Cd were low, indicating that Cr and Cd were easily released from the surface sediments, causing secondary pollution. In terms of the source of the heavy metals, Cu, As, Zn, Cr, and Ni mainly came from industrial and agricultural wastewaters, Pb was from the mining industry and natural sources, and Mn and Cd mainly came from tailings and their landfill leachate. Basommatophora and Araneae can be used as potential indicator organisms for heavy metal pollution in surface water, and Basommatophora, Coleoptera, Hemiptera, and Araneae can be used as indicator species for heavy metal pollution in surface sediments. The study showed that macroinvertebrate community characteristics had a sensitive response to heavy metals in the surface waters and sediments of the Heihe River, which can be used to evaluate the pollution status of heavy metals in inland rivers.

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Fish are some of the most threatened vertebrates in the world due to their often-sensitive response to environmental changes. Major land-use changes in the European Alps have direct and indirect impacts on fish communities, and these impacts are expected to increase in the future. Therefore, the identification of factors that are associated with the distribution of fish communities is of great importance to develop guidelines for management, precautions and sustainable use of running waters. In this study, the relationship of various factors - landscape structure and land use, topography, morphology, hydrology, physical and chemical water characteristics, hormonally active substances, pesticides, food availability, fisheries and piscivores birds - with fish assemblages are analysed. Field data from 81 stream sections from 2001 metres above sea level (m.a.s.l.) down to 219 m.a.s.l. are used in the study. The results reveal that the number of fish species has a strong association with topographic characteristics in the catchment area as well as with landscape configuration. Fish abundance and biomass are associated mostly with land-use type, hydrology, morphology as well as topography. In addition, there are indirect connections between fish abundance and biomass through land-use type, topography, water properties and hydromorphology. The results clearly indicate that not a single factor, but a multitude of factors are associated with the fish communities in the Eastern European Alps.

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The increasing concerns and management needs on marine biodiversity have escalated the requirement for timely documentation of the marine taxa. We first established a comprehensive ecological checklist of Korean Brachyura through a meta-analysis of 74 documents (since the 1870s). A total of 247 species inhabiting the Korean coastal waters are listed with some key ecological information; habitat, substrate, distribution, and delta +. The crabs predominated on Jejudo Island, at the southernmost point of Korea, followed by the South Sea, West Sea, and East Sea. Portunus trituberculatus and Hemigrapsus sanguineus were cosmopolitan species widely distributed across the three seas. Dynamic oceanographic settings of the South Sea, such as archipelago, Rias coast, varied habitats, and (in)direct influence of Kuroshio warm current, seemed to support high crab diversity. The rocky and subtidal habitats represented biodiversity hotspots. The present study would be a useful baseline for gathering further ecological information of globally important marine taxa in Korea and elsewhere.

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Lake eutrophication and algal blooms may result in the mortality of macrozoobenthos. However, it is still not clear how macrozoobenthos decomposition affect phosphorus (P) mobility in sediments. High-resolution dialysis (HR-Peeper) and the diffusive gradients in thin films (DGT) technique were used in this study to assess the dissolved organic matter (DOM), dissolved/DGT-labile iron (Fe), P, and sulfur (S(-II)) profiles at a millimeter resolution. The decomposition of Bellamya aeruginosa significantly increased the internal loading of sediments P. The Fe(III) and sulfate were reduced under anaerobic conditions and promoted P desorption from sediments. This was supported by the significant increase in DGT-labile S(-II) and dissolved/DGT-labile P, Fe(II) and the significant positive correlation between Fe and P on day 8. The simultaneous increase in DOM and soluble reactive phosphorus (SRP) and the significant positive relationship between these factors were observed during the decomposition of B. aeruginosa. This suggested that complexation of DOM with metals may promotes the release of P from sediments.

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To understand the status and dynamics of macrozoobenthos community in Sanmen Bay, we collected benthos samples by Agassiz trawl in November 2015, and February, May and August in 2016. The results showed that: 1) A total of 119 macrozoobenthos species were recorded, with main groups of fishes, crustaceans and molluscs, accounting for 79% of the total number of species. 2) The dominant species of macrozoobenthos throughout the year were Leptochela gracilis, Hyperacanthomysis longirostris and Amblychaeturichthys hexanema. The identity of dominant species changed significantly in different seasons. 3) The annual average biomass and density were 0.025 g·m-2 and 0.07 ind·m-2, respectively. 4) The Shannon's diversity index of macrozoobenthos in Sanmen Bay varied from 2.21 to 3.18, the Margalef's species richness index varied from 3.25 to 3.78, and the Pielou's evenness index varied from 0.53 to 0.79. Results from abundance-biomass curve analysis showed that the community was moderately disturbed in spring and winter, and slightly disturbed in summer and autumn. Results from Canonical correspondence analysis showed that water depth, temperature, salinity, and pH were the most important environmental factors affecting macrozoobenthos community.

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Various ecological communities are susceptible to the salinity gradients in coastal wetlands. Remane diagram has well described the macrozoobenthos diversity pattern along salinity gradients. Yet, further research is still needed, that is, the changes in diversity and biomass of other communities (e.g. plants, fish) along salinity gradients, and whether these changes are consistent or different among different communities. In this study, using China's Yellow River Delta wetland as a case study, we analyzed the variation of the community composition, species richness, and biomass of plant, macrozoobenthos, and fish communities along a salinity gradient from <0.5 to 30 ppt. We found that plant community composition exhibited more distinct variation along the salinity gradient than macrozoobenthos, with the least distinction for fish. Plant species richness decreased greatly along the gradient, whereas macrozoobenthos richness first decreased and then increased with increasing salinity, with the low richness occurring at a salinity of 0.9-12.3 ppt. Fish had the highest richness at a salinity of 14.8-16.0 ppt. The sum of plant, macrozoobenthos, and fish species and macrozoobenthos richness were both similar to the Remane diagram. Plants had higher biomass in low-salinity zones than in high-salinity zones, except for high biomass at a salinity of 14.8-16.0 ppt, whereas macrozoobenthos and fish showed the opposite trend. Principal-coordinate analysis showed an obvious dissimilarity map based on the composition, richness, and biomass of the plant, macrozoobenthos, and fish communities. Overall, the effects of salinity gradient differed among different communities. These findings demonstrate the asymmetric responses of different communities to salinity gradients, and have practical implications for maintaining a salinity gradient in coastal wetlands.

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