Use of body-size distinctness of biofilm-dwelling protozoa for marine bioassessment

As an inherent function of a community, body-size spectrum has proved to be a robust indicator for functional community research and global bioassessment. To determine the feasibility of body-size distinctness of biofilm-dwelling protozoa for marine bioassessment, a set of data points of the protozoa, which was monthly collected at four stations within a gradient of pollution in coastal waters of the Yellow Sea, northern China during a 1-year cycle, was studied. The body-size spectra of the protozoa showed a clear spatial pattern in response to the water quality status among four sampling stations. The average body-size distinctness (Delta(+)(z)) and variation in body-size distinctness (Delta(+)(z)) were used to evaluate the water quality status based on a Euclidean distance resemblance and a modified hierarchy of body-size units, respectively. The paired distinctness measures (Delta(+)(z) and Delta(+)(z)) based on both traits showed a significant departure from the expected trait hierarchy of body-size spectrum. These results suggest that the body size distinctness measures may be a useful indicator for discrimination of water quality status in marine ecosystems, using biofilm-dwelling protozoa. (C) 2015 Elsevier Ltd. All rights reserved.