Biological trait patterns of periphytic protozoa at different depths in the coastal water of the Yellow Sea

The distribution of biological traits of the ciliated protozoa is of great significance to water quality detection of marine ecosystems. The homogeneity of the spectrum of functional traits of periphytic ciliates communities were studied at four water depths in coastal waters of the Yellow Sea. According to the variations in community-weighted mean values based on both frequency of occurrence (FO) and probability density (PD), the ciliated protozoan communities represented different spectra of functional traits at four water depths. Multivariate approaches for four depths demonstrated that the functional trait spectrum of FO and PD at depths of 2-3.5 m were significantly different from the other two depths (1 and 5 m). The average functional distinctness (Delta(+)(chi)) and variation in functional distinctness (Lambda(+)(chi)) indices generally levelled off at depths of 2-3.5 m which indicated that 2-3.5 m would be an optimal sampling strategy in shallow coastal waters. These results suggest that the functional distinctness may be as a feasible tool for detecting the homogeneity in the functional trait spectrum of the ciliated protozoa for ecological research. (C) 2020 Elsevier B.V. All rights reserved.