Studies on the Community Structures of Meiofauna and Marine Nematode at Six Stations in the Southern Yellow Sea,China

Meiofauna (0.031 -0.5 mm) were sampled and studied at a grid of six stations during the cruise of investigation for over winter ground of anchovy (Engraulis japonicus) in the Southern Yellow Sea, China in January 2003. Total meiofauna individuals averaged (1.162 ±0.347) x 10~6 indm-2 and the corresponding biomass 1.748 ± 0.72 gdwt m-2 with the maximum 2.35gdwtm-2 at Station 9594 and the minimum 0.537 gdwtm- at Station 11794. A total of fourteen taxa were identified. 2 Free living marine nematodes were the most dominant group with an average abundance of (1.026 ± 0.206) x 10~6 indm- , ac-2 counting for 88.5% of total numbers, and an average of 85.4% lived in the surface layer (0-2cm) of sediments. The individ- ual dry weight was calculated, which ranges from 0.01μg to 31.32μg with an average of 0.261μg. One hundred and forty two species or taxa of free-living marine nematodes belonging to 89 genera, 24 families and 4 orders were identified. Six of them were new species. The common dominant species were Dorylaimopsis rabalaisi, Sphaerolaimus balticus, Sphaerolaimus mini- tus, Metalinhomoeus longicauda, Prochromadorella attenuata., Campylaimus sp. 1, Vasostoma sp. 1, Daptonema nor- mandicum, Paramonohystera riemanni, and Promonhystera sp. 1. According to cluster analysis of Primer 5.0, the six stations were clustered into 2 groups with similar species composition at 40% similarity. The species diversity index (H’), evenness index (J) and species richness index (d) of nematode were calculated and analyzed. Correlation analysis with respect to en- vironmental factors showed that the abundance of meiofauna had a significant correlation with the median diameter of sedi- ment (Mdtf). The species richness of nematodes had a highly significant correlation with Chl-a and significant correlations with Pha-a and Chl-a+ Pha-a.

Meiofauna (0.031-0.5 mm) were sampled and studied at a grid of six stationsduring the cruise of investigation for over winter ground of anchovy (Engraulis japonicus) in theSouthern Yellow Sea, China in January 2003. Total meiofauna individuals averaged (1.162 ± 0.347) x10^6 ind m^(-2) and the corresponding biomass 1.748 ± 0.72 g dwt m^(-2) with the maximum 2.35 g dwtm^(-2) at Station 9594 and the minimum 0.537 g dwt m^(-2) at Station 11794. A total of fourteentaxa were identified. Free living marine nematodes were the most dominant group with an averageabundance of (1.026 ± 0.206) x 10~6 ind m^(-2), accounting for 88.5% of total numbers, and anaverage of 85.4% lived in the surface layer (0-2cm) of sediments. The individual dry weight wascalculated, which ranges from 0.01 μg to 31.32 μg with an average of 0.261 μg. One hundred andforty two species or taxa of free-living marine nematodes belonging to 89 genera, 24 families and 4orders were identified. Six of them were new species. The common dominant species were Dorylaimopsisrabalaisi, Sphaerolaimus balticus, Sphaerolaimus mini-tus, Metalinhomoeus longicauda,Prochromadorella attenuata., Campylaimus sp. 1, Vasostoma sp. 1, Daptonema nor-mandicum,Paramonohystera riemanni, and Promonhystera sp. 1. According to cluster analysis of Primer 5.0, thesix stations were clustered into 2 groups with similar species composition at 40% similarity. Thespecies diversity index (H′), evenness index (J) and species richness index (d) of nematode werecalculated and analyzed. Correlation analysis with respect to environmental factors showed that theabundance of meiofauna had a significant correlation with the median diameter of sediment (Md_φ).The species richness of nematodes had a highly significant correlation with Chl-a and significantcorrelations with Pha-a and Chl-a + Pha-a.