Species diversity and functional trait-based approaches in ecological assessment utilizing free-living marine nematodes in Jiaozhou Bay, China

The present study evaluated the potential application of free-living marine nematode assemblages as indicators in assessing environmental condition of Jiaozhou Bay (JB), China. Shannon-Wiener diversity (H'), functional trait indices (Index of Trophic Diversity, ITD and Maturity Index, MI) were utilized to rank the benthic habitat quality of the sampled stations. Most of the nematode genera/species belonged to c-p (colonizer-persister) class 2, indicating dominance of opportunistic nematodes and suggesting organic enrichment in the bay. Based on nematode indices, the ecological condition varied from bad to good. Ranking variations were observed among different indices, suggesting different sensitivity of nematode indices to different types of disturbance. Based on the final ecological quality assessment (EcoQ), most sampled stations were ranked as moderate (station J1 was ranked as poor). Nematode indices are more indicative of the influence of land based discharges. For a comprehensive assessment of benthic ecosystem, combined meiofauna and macrofaunal indicators were suggested.