Effects Of Sewage Discharge On The Macrobenthic Community Offshore Area Of Yantai,Shandong Province

With the aim of understanding the status of microbenthic community and its suffers from the the sewage discharge,a survey was carried out in September 2012 on 10 sampling stations at the water areas near to zhifu Island,offshore area of Yantai,Shandong province.Based on the water and species samples collected during this survey,the community characters were analyzed,including the species composition,abundance,biomass,dominant species,biodiversity indices and community structure of macofauna.The relationship between macrofauna community structure and the environment factors was also illuminated by software PRIMER.A total of 66 macrobenthic species were identified,including 35 species of Polychaetes,13 species of Molluscan,11 species of Crustacean,3 species of the Echinoderm,3 species of other groups,of which the dominant group was Polychaetes.Ten dominant species were identified,namely,Sternaspis sculata,Eriopisella sechellensis,Moerella iridescens,Lumbrineris cruzensis,Amaeana occidantalis,Paralacydonia paradoxa,Glycinde gurjanovae,Nephtys polybranchia,Heteromastus filiformis and Anthura gracilis.The average biomass and abundance was 8.55 g/m2 and 619.67 ind./m2,respectively,of which Molluscan species contributed most to biomass and Polychaetes contributed most to abundance.Three biodiversity indices,Shannon-Wiener index,Richness index and Evenness index were 3.173±0.102,5.469±0.417 and 0.965±0.007 respectively.The species composition at station Z2(nearest to the sewage discharge point)was dominated by polychaetes and showed a miniaturization trend in body size.CLUSTER and MDS analysis showed that macrobenthic assemblages could be significantly divided into three sub-groups based on 60% similarity.Abundance and biomass curves indicated that over 80% of the stations suffered from moderate disturbance due to anthropogenic activities.However,the AMBI and M-AMBI results showed that the macrobenthic ecological status of the research area was between good to high.Environmental data showed that the research area was facing with the risk of ocean acidification and underlying hypoxia.Compared with previsous reports,some extent of community succession has been observed,as well as the miniaturization tendency in body size and decreasing biodiversity.