Biodiversity of Free-Living Marine Nematodes in the Southern Yellow Sea, China

Biodiversity pattems of free-living marine nematodes were studied using specific, taxonomic and phylogenetic diversity measures in the southern Yellow Sea, China. The results showed that the average of Shannon-Wiener diversity index （H＇） in the study area was 3.17. The higher values were distributed in the east part of Shandong coastal waters and north part of Jiangsu coastal waters, while the lower values were distributed in the southern Yellow Sea Cold Water Mass （YSCWM）. The average of taxonomic diversity （A） was 62.09 in the study region. The higher values were distributed in the transitional areas between the coastal areas and the southem YSCWM, while the lower values were distributed near the north part of Jiangsu coastal waters and the YSCWM. Results of correlation analysis of species diversity and taxonomic diversity showed that some of the two kinds of diversity index were inde- pendent, which suggested that combining the two kinds of diversity indices can reflect the ecological characteristics better. A test for 95% probability funnels of average taxonomic distinctness and variation in taxonomic distinctness suggested that Station 8794 （in the YSCWM） was outside of the 95% probability funnels, which may be due to the environmental stress. Results of correlation analysis between marine nematodes biodiversity and environmental variables showed that the sediment characteristics （Mdo and Silt-clay fraction） and phaeophorbide a （Pha-a） were the most important factors to determine the biodiversity patterns of marine nematodes.