Plankton ciliate community responses to different aquatic environments in Nan'ao Island, a representative mariculture base in the South China Sea

Abstract

The temporal variation and spatial distribution of plankton ciliate communities were investigated in Shen’ao Bay, South China Sea. In all, 35 species belonging to 17 genera and 7 orders were identified. The number of ciliate species was lower in spring than in summer, whereas ciliate abundance was higher in spring than in summer. Spatially, the number of ciliate species and ciliate abundance were higher in the oyster–algae mixed culture area and non-aquaculture area, and lower in the caged fish culture area. Multivariate and univariate analyses demonstrated that ciliate communities were associated with environmental factors (e.g. temperature, chlorophyll (Chl)-a, nutrient levels). In addition, two dominant species, namely Mesodinium rubrum and Tintinnopsis beroidea, were significantly positively correlated with Chl-a. Three dominant species, namely Strombidium globosaneum, Tintinnopsis minuta and Strombidium conicum, showed more sensitivity to dissolved oxygen, pH and chemical oxygen demand, whereas Tintinnopsis parvula and Tintinnopsis chinglanensis were significantly related to NO2–. Ciliate species diversity, species evenness and species richness were higher in the oyster–algae mixed culture area and non-aquaculture area and lower in the caged fish culture area. Therefore, the results of this study suggest that the ciliate community is significantly correlated with its aquatic habitat and the dominant species can be considered a favourable bioindicator of the marine water environment.