Abstract:Based on the data collected by trawl surveys in June and July of 2010 in Huanghe estuary and its adjacent area, fish community patterns such as species compositions, dominant species, spatial distribution, diversity and similarity were studied. In the investigated area, 37°30′~38°00′N, 119°09′~119°30′E, eight sampling stations were set up. A total number of 32 species were collected in the present study, and all of them were Osteichthyes species, belonging to 32 genera, 21 families and 7 orders. There are 4 groups according to their habitat type, in which 7 species were continental shelf pelagic-neritic fish, 18 species were continental shelf benthopelagic fish, 7 species were continental shelf demersal fish, and 1 was continental shelf reef-associated fish. According to their optimum living temperature, fish species were divided into 3 fish groups, including 9 warm water species, 16 warm temperate species and 7 cold temperate species. There were seven fish groups according to the analysis of feeding habit: 6 species were planktivores, 4 species were planktivores/benthivores, 7 species were benthivores, 5 species were benthivores/piscivores, 1 species was piscivores, 7 species were omnivores and 2 species were detritivores. The index of relative importance (IRI) was calculated to determine the importance of the species. Species were defined as dominant species when IRI value was larger than 1000. There dominant species were Chaeturichthys stigmatias, Cynoglossus joyneri and Acanthogobius ommaturus in June and C. stigmatias, Konosirus punctatus, C. joyneri and A. ommaturus in July. The biomass and abundance of fish increased greatly in survey before WSDR were grouped than those in survey after WSDR. The Margalef richness index (D), Shannon's diversity index (H′) and Pielou's evenness index (J′) of fish community in the survey before WSDR were all higher than those in survey after WSDR. But no significant differences were found in the diversity between the two surveys. Cluster analysis and non-metric multidimensional scaling were used for analyzing fish community structure. The results showed that community structure was obviously different between the two surveys. The 8 stations surveyed before WSDR can be grouped into one group, and the 8 stations surveyed after WSDR were grouped into another group. The dissimilarity was caused mostly by the biomass composition and its spatial distribution of C. stigmatias, K. punctatus, A. ommaturus,Scomberomorus niphonius, Platycephalus indicus and C. joyneri. The similarity of the community in the two surveys was low. The Jaccard's species similarity coefficient was 56.3%, and the Bray-Curtis similarity coefficient was 43.1%. In conclusion, compared with the survey data of 1980s, the numbers of fish species in the Huanghe estuary and adjacent area showed a downward trend, and the biomass distribution of fish in scale of time and dominant species composition changed significantly.
