Application of an indicator based on taxonomic relatedness of ciliated protozoan assemblages for marine environmental assessment.

INTRODUCTION Ciliated protozoa play important roles in aquatic ecosystems especially regarding their functions in micro-food web and have many advantages in environmental assessment compared with most other eukaryotic organisms. The aims of this study were focused on analyzing the application of an indicator based on taxonomic relatedness of ciliated protozoan assemblages for marine environmental assessment. MATERIALS AND METHODS The spatial taxonomic patterns and diversity measures in response to physical-chemical variables were studied based on data from samples collected during 1-year cycle in the semi-enclosed Jiaozhou Bay, northern China. RESULTS The spatial patterns of ciliate communities were significantly correlated with the changes of environmental status. The taxonomic distinctness (Δ*) and the average taxonomic distinctness (Δ+) were significantly negatively correlated with the changes of nutrients (e.g., nitrate nitrogen and soluble active phosphate; P<0.05). Pairwise indices of Δ+ and the variation in taxonomic distinctness (Λ+) showed a decreasing trend of departure from the expected taxonomic breadth in response to the eutrophication stress and anthropogenic impact. CONCLUSION The taxonomic relatedness (especially the pairwise Δ+ and Λ+) indices of ciliate communities are robust as an indicator with scientifically operational value in marine environmental assessment.