Use of biological trait analysis of periphytic protozoan assemblages for evaluating effects of harmful algal blooms on ecological quality status in marine ecosystem.

Abstract The effects of two harmful algal bloom (HAB) species Alexandrium tamarense and Gymnodinium catenatum on ecological quality status were studied using 14-day protozoan samples as test organisms. A fuzzy coding system with four traits and 11 categories of the test organisms was used for biological trait analysis. Five treatments were designed following the concentrations of 100, 102, 103, 104 and 105 cell ml‐1 of each algal species. The community-weighted means were used to summarize the functioning process of the test organism assemblages. The community functioning of the protozoa showed a significant change in the treatments with high algal concentrations (104 and 105 cell ml−1). The functional richness of the test organisms showed continuous increasing trend from 102 to 104 cell ml−1, and sharply dropped. These findings suggest that the BTA may be used as a useful tool for assessing the effects of HABs on ecological quality status in marine ecosystems.