Community structure of Cephalopods and its relationships with environmental factors in Laizhou Bay, Bohai Sea

The community structure of Cephalopods and its relationship with environmental factors were analyzed based on the bottom trawl data of nine months from May 2011 to April 2012, in order to reveal the resource status of Cephalopods in Laizhou Bay. A total of 6 species belonging to 3 orders, 3 families, 4 genera, were collected by 148 hauls. Both the biomass density and the individual density were highest in October 2011 and lowest in March 2012. The annual average of biomass density and individual density were 3 111.39 g/h and 723.54 ind/h, respectively. Loligo sp. was the dominant species, with the annual index of relative importance (IRI) reaching up to 13097. The spatial distribution of individual density of Cephalopods changed with different month in Laizhou Bay. The individual density of Cephalopods was the highest in the central and southern Laizhou bay from June to July, and the highest in the central and northern Laizhou bay from August to November 2011. The individual density of Cephalopods were very low from March to May. CLUSTER and MDS analysis indicated that 9 months were divided into 4 groups at 85% similarity level. ANOSIM analysis indicated that the community structure of Cephalopods of random two groups were significantly different. SIMPER analysis indicated that Loligo sp. contributed the most to the group distinguishing. Pearson correlation analysis indicated that the density of zooplankton matched the density of Cephalopods best. Reproductive migration and wintering migration were the principal influence factors on the variation of spatial distribution of Cephalopods in Laizhou Bay. The present results would be helpful to better utilizing and protecting the Cephalopods resources in Laizhou Bay.