Effects of latitude gradient and seasonal variation on the community structure and biodiversity of commercially important crustaceans in the Yellow Sea and the northern East China Sea

To evaluate the spatio-temporal variations in the community structure and biodiversity of commercially important crustaceans in the Yellow Sea and the northern East China Sea(NECS),the seasonal and regional changes in species composition,biomass structure,biodiversity and distribution of commercially important species were analyzed using bottom trawl survey data during 2014-2015.The results showed that the latitudinal gradient was obvious in species richness,dominant species and biodiversity.The indices of biodiversity increased with the decreasing latitude.When the sampling sites shifted south by one latitudinal degree,Margalefs richness index(D),Pielou's evenness index(J')and Shannon-Wiener diversity index(H')increased by 0.10.0.03 and 0.09,respectively.The biomass proportion of the cold-temperate species represented by Crangon affinis declined with the decreasing latitude,and the warm-temperate species represented by Ovalipes punctatus and Portunus trituberculatus in creased.Because of the growth regulatio n of crustaceans and the fishing moratorium,the biomass of commercially important crustaceans in the Yellow Sea and NECS was highest in October and August,respectively.Salinity had a more significant influence on H'of commercially important crustaceans than other environmental factors(including zooplankton density,sea bottom temperature and water depth).Overall,the results of this study contribute to a better understanding of community dynamics of crustaceans in the Yellow Sea and NECS,and provide evidence to verify the latitudinal gradient theory in biodiversity.