Characteristics of macrobenthic communities and their response to environmental changes in East Taihu Lake, China

Abstract

East Taihu Lake watershed has complex water functional areas; though it is small, human activities on the East Taihu Lake watershed environment interference are relatively strong. In this study, we investigated the diversity of macrobenthic communities and analyzed the pivotal environmental factors affecting alterations in the macrobenthic communities of East Taihu Lake. This analysis was augmented by controlled laboratory simulation experiments designed to elucidate and validate the responses of critical indicator species within various functional areas to environmental shifts. This study showed that (1) 28 species of macrobenthos were collected in the study area, belonging to 3 phyla, 6 orders, 13 orders, 18 families, and 25 genera. The mean values of annual macroinvertebrate density and biomass were 70.93 ± 42.92 ind/m² and 50.99 ± 36.50 g/m². Bellamya purificata, Limnodrilus, and Tubifex were the dominant species on a year-round scale. Water depth and sediment water content were the most important environmental factors affecting the macrobenthic communities; (2) simulation experiments revealed that the growth condition of Bellamya was significantly worse in the simulated entrance area than in the simulated original enclosure aquaculture and wetland areas. The growth of Radix auricularia was significantly better in the presence of aquatic plants than in the absence of plants, and was more significantly influenced by environmental factors closely related to aquatic plants. The densities of annelids were significantly higher in the treatment group without plants than in that with plants, generally showing the growing trend of the simulated original enclosure aquaculture area > the simulated entrance area > the simulated wetland area. The results of the study support an aquatic revegetation strategy dominated by submerged plant restoration, and recommend water level regulation in shallow lake areas to reduce the impact of water level fluctuations on benthic habitats.