Seasonal variation of fish community structure in Zhelin Bay, the South China Sea

Based on the date collected by quarterly otter trawl surveys in Zhelin Bay from 2011 to 2012, we analyzed the fish species composition, resources structure and trophic level. A total of 99 fishes were collected during the surveys. The proportions of demersal fish, tropical fish, and carnivorous fish were 49.49%, 78.78% and 79.79%, respectively. The composition of the dominant species of biomass and abundance percentages was similar, including Parachaeturichthys polynema, Harpodon nehereus and Johnius belengeri. The maximal biomass and abundance of fish were in summer in Zhelin Bay. The average body weight of fish in four seasons was less than 15 g. The composition of fish was more abundant in spring and autumn. The dominance of biomass of fish was the highest in winter. The feeding habit of fish in Zhelin Bay was mainly intermediate carnivorous and advanced carnivorous. The change of trophic level of four seasons was inconspicuously. The annual average trophic level index was 3.478 of intermediate level. It was in summer that the average body weight of high trophic level fish peaked.