SEASONAL VARIATIONS OF FISH RESOURCES AND COMMUNITY DIVERSITY OF REEF HABITAT IN MARINE PROTECTED AREA OF ZHONGJIESHAN ISLANDS

We conducted this research on fishery resource in the Marine Protected Area(MPA) of Zhongjieshan Islands located in the central area of the Zhoushan fishing ground, Zhejiang, a well-known warehouse in the East China Sea, setting four sampling zones in reef habitat and gillnet every three month from February 2011 to November 2012. The fish composition, diversity characteristic and community stability in the MPA were studied using indices including Margalef's species richness index, Shannon-Wiener's species diversity index, Pielou's species evenness index, relative resource abundance, Pinkas' s IRI as well as alternation and migration index. In this project, 58 fish species, 8 orders, 31 families, and 48 genera were recognized. Order Perciformes was the dominant for having 26 species, accounting 44.8% of the total species. Specifically, warm temperate species and warm water species were the main members; 79% of total individuals were reef species; and 21 were demersal species, 23 meso-demersal species, and 14 pelagic species. In addition, dominant species in each habitat layer was examined: Sebastiscus marmoratus was the most abundant demersal fish; and Johnius belengerii was the most dominant meso-demersal fish. Engraulis japonicus dominated the surface waters. S. marmoratus made great contribution to relative abundance(RA) in autumn and winter, while E. japonicas in spring and summer. The highest and lowest of Margalef's species richness index, Shannon-Wiener's species diversity index and alternation Index(AI) were in summer and winter, but the Pielou's species evenness index showed the opposite characteristics, and the evenness index in winter was significantly different from that in summer(P0.01). The fish biomass in the MPA was significantly influenced by temperature, while the fish community composition pattern by seasonal variations. Overfishing was considered responsible to the decline in fish diversity of reef habitat. Therefore, development and management for marine ranching in reef habitat shall be enforced.