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The impact of two high‐head dams on macroinvertebrate communities within the regulated reaches of the Wujiang River in China was explored, using longitudinal monitoring data spanning from 2006 to 2016. In this study, we set up 10 sampling sites categorized into four areas based on different stressors and defined three stages based on the timeline of dam construction. Our findings revealed significant changes in community composition before and after dam impoundment. While certain original dominant taxa, such as Rivularia globosa and Lithoglyphopsis ovatus, remained dominant throughout the stages, mayflies and caddisflies nearly vanished in the downstream reaches of the dams. This trend was accompanied by the disappearance of taxa with low adaptability and the emergence of tolerant taxa downstream of the dams. Additionally, typical limnological taxa colonized the inundated reaches. Dam impoundment affected not only macroinvertebrate community composition but also diversity. In this study, the recovery effect of communities downstream of dams was not observed due to the limited distance, but the presence of Wujiangdu Dam upstream of the two dams for over 20 years makes us believe that in a large river system, macroinvertebrate communities downstream of high‐head dams may fully recover if the distance from the dams is long enough. The original and vulnerable species R. globosa, which demonstrated remarkable adaptability and thrived downstream of dams, should be further studied in the future. [ABSTRACT FROM AUTHOR]

In this study, we investigated the plankton, water, and macroinvertebrates in Nanwan Reservoir, a subtropical eutrophic reservoir with thermal stratification. We evaluated the status of macroinvertebrate communities and explored the relationships between macroinvertebrate community status and both abiotic and biotic factors. This reservoir exhibited the worst water quality and a high risk of algal blooms in the autumn, whereas it had the best water quality in the spring. The presence of thermal stratification adversely affected macroinvertebrate communities, leading to decreases in species richness, abundance, and diversity. The water characteristics and dominant macroinvertebrate species confirmed that the reservoir was experiencing progressive eutrophication. During the thermal stratification period, the reservoir exhibited a worse status of macroinvertebrate communities, accompanied by an abundance of plankton. The results of PLSR and the Spearman rank test revealed that several abiotic factors, such as water temperature, chlorophyll-a, soluble phosphate, pH, and transparency, as well as biotic factors including the abundance of protozoans, Cyanobacteria, phytoplankton, Bacillariophyta, and Euglenophyta, were the most important factors affecting macroinvertebrate communities. The results of PLS-SEM revealed that both abiotic factors and biotic factors had non-negligible effects on the status of macroinvertebrate communities, with higher effect from abiotic factors compared to biotic factors. [ABSTRACT FROM AUTHOR]

The Big East Lake water network (BELWN), located in Wuhan city, China, is mainly composed of six lakes and isolated from the Yangtze river. At the background of restoring the hydrological connectivity between rivers and lakes, four season investigations were conducted during 2014–2015 to study the spatial distribution and seasonal dynamics of macroinvertebrate communities, explore their relationships with environmental factors, and forecast the change trends in assemblages in a long period after restoration measures. A total of 40 species were recorded, oligochaetes and chironomids dominated the communities. Season variation in density and biomass were distinct and the community differences in lakes related to the degrees of organic pollution. In comparison with the historical data, the species richness of mollusks in Donghu lake sharply decreased due to water pollution and the loss of diverse habitat. Concerning on the whole BELWN, the whole taxa recorded in our study was slightly fewer than the previous study. A new recorded species polychaete Nephtys sp. was first collected with an important ecological interest. As an urban lake system dominated by eutrophication, the water nutrients significantly affected the distribution of macroinvertebrates. According to the GAM models, the dominant species responded to environmental gradients with different response curves. After restoring the hydrological connectivity between rivers and lakes, the macroinvertebrate communities would change and the biodiversity would steadily increase with time. Additionally, the new recorded species Nephtys sp. would spread into the whole BELWN in the foresee future.

This study introduced a multimetric index (CSMMI) developed in the Chishui River, China. As the only one undammed river in Yangtze River basin, the Chishui River still maintains properties of natural rivers and is regarded as an ideal river for pilot biological monitoring on water quality. The aim of this study is to establish biocriteria based on macroinvertebrates for water quality assessment and a sustainable management framework, and enhance integrated river basin management in the Yangtze River basin. Seventy-one sampling sites were set up to collect biological and water samples. According to certain steps, 4 core metrics were selected from 57 candidate metrics and regarded as sensitive to pollution and joined into the final system, including the metrics ScrapPct, EphemTax, ASPT and EPTPct. Four final metrics were from different metric groups and highly related to several water parameters, and the CSMMI index was also significantly correlated with the pollution gradient extracted from the macroinvertebrate community data. The deviation rates between chemical and biological assessment were acceptable. The results of application evaluation indicated the CSMMI index were a robust and reliable tool for bioassessment, possibly adapted and used in the adjacent rivers. [ABSTRACT FROM AUTHOR]