An approach to determining functional parameters of microperiphyton fauna in colonization surveys for marine bioassessment based on rarefaction curves.

The functional parameters, i.e., the estimated equilibrium species number (S eq), the colonization rate constant, and the time taken to reach 90 % of S eq (T 90), of microperiphyton fauna have been widely used to determine the water quality status in aquatic ecosystems. The objective of this investigation was to develop a protocol for determining functional parameters of microperiphyton fauna in colonization surveys for marine bioassessment based on rarefaction and regression analyses. The temporal dynamics in species richness of microperiphyton fauna during the colonization period was analyzed based on a dataset of periphytic ciliates in Chinese coastal waters of the Yellow Sea. The results showed that (1) based on observed species richness and estimated maximum species numbers, a total of 16 glass slides were required in order to achieve coefficients of variation of <5 % in the functional parameters; (2) the rarefied average species richness and functional parameters showed weak sensitivity to sampling effort; (3) the temporal variations in average species richness were well-fitted to the MacArthur-Wilson model; and (4) the sampling effort of ~8 glass slides was sufficient to achieve coefficients of variation of <5 % in equilibrium average species number (AvS eq), colonization rate (AvG), and the time to reach 90 % of AvS eq (AvT 90) based on the average species richness. The findings suggest that the AvS eq, AvG, and AvT 90 values based on rarefied average species richness of microperiphyton might be used as reliable ecological indicators for the bioassessment of marine water quality in coastal habitats.