An approach to discriminating water quality status based on trophic-functional diversity of periphytic protozoan communities in marine ecosystems

To determine the sensitivity of trophic-functional diversity of periphytic protozoa to envi-ronmental change, a 1-year baseline survey was carried out using glass microscope slides as artificial substrates at four sampling sites along a pollution gradient in coastal waters of the Yellow Sea, northern China. Eight trophic-functional groups were identified from 144 observed species based on feeding type and food resource. Results showed that: (1) bacterivores increased, while algivores and non-selectives decreased in abundance with increasing levels of pollution; (2) the trophic-functional pattern of the biofilm-dwelling protozoan communities showed a significant variation among the four sites; and (3) the ellipse test based on paired trophic-functional distinctness indices ( A 9,+ and A,y+) indi-cated a significant departure from an expected trophic-functional pattern in polluted areas. Based on these findings, it is suggested that trophic-functional distinctness of periphytic protozoa may be a feasible bioindicator of marine water quality.(c) 2022 Published by Elsevier B.V. on behalf of European Regional Centre for Ecohydrology of the Polish Academy of Sciences.