Species composition and diversity of macrobenthic fauna in Daya Bay

Daya Bay is a nature reserve for fisheries resources. However,there are conflicts between economic development and conservation,and ecosysterm. And the habitat is degrading due to anthropogenic influences. Based on grab samples of macrobenthos collected in Daya Bay in 1984-1985,1987-1988,and 2004,comparisons were conducted to investigate changes in faunal assemblage and species diversity over the past two decades. Results show that habitat degradation has led to decrease of species diversity. The average number of species collected per station was 50.6 with a maximum of 100 species in 1987-1988. However in 2004,the average species number per station decreased to 7.6 with a maximum of only 14 species. From 1987-1988 to 2004,the Shannon-Wienner diversity indices (H') declined from 3.38 to 2.08,and species richness indices from 4.46 to 1.17. However,horizontal pattern of high diversity in the north and low diversity in the south remainsd basically unchanged,and evenness indices showed slight increase. In 1984-1985,totally 98 macrobenthic species were collected,comprising 31 species of molluscs,12 polychaetes,30 crustaceans,and 21 echinoderms. In 2004, totally 79 species were collected,consisting of 32 molluscs,18 polychaetes,17 crustaceans,and 8 echinoderms. Between 1984-1985 and 2004,the Jaccard’s coefficient(Js)donating species similarity was only 25.5%, and the lowest coefficient of 8.1% was observed for polychaetes,indicating remarkable changes in faunal assemblages.