Distribution characteristics of the benthic macroinvertebrates and corresponding influencing factors in Jiuduansha shoals

Abstract

The benthic macroinvertebrate is one of the most important biological groups in salt marsh ecosystem. The Jiuduansha shoals of the Changjiang Estuary were selected as the study areas, and fixed sampling sites were set along the elevation gradient in the different areas, and the benthic macroinvertebrates, sediments and plants were sampled for the analysis on the distribution characteristics of the benthic macroinvertebrates and corresponding influencing factors. The results showed that: (1) The distribution of the benthic macroinvertebrates along elevation gradient has certain regularity: The abundance and biomass of annelids in the low tidal zone appeared to be the highest, the species number of mollusks in the middle tidal zone was the highest, and the abundance and biomass of crustaceans in the high tidal zone were the highest. (2) Due to the differences of environmental conditions, the distribution characteristics of the benthic macroinvertebrates along the elevation gradient were also significantly different among the different areas. (3) Habitat factors that have significant effects on the distribution characteristics of the benthic macroinvertebrates included the median grain size, the redox potential of sediments, the density of plants, etc, and there were some differences among the different areas and habitats. (4) The invasion of Spartina alterniflora changed the habitat conditions and thus affected the distribution characteristics of the benthic macroinvertebrates. In future studies, we should fully consider the differences of environmental conditions between the different areas and elevations to explore the distribution characteristics of the benthic macroinvertebrates and the comprehensive effects of the influencing factors.