Analysis on community structure of shellfish and its characteristics of biomass particle size spectrum in Yueqing Bay, China

The sediment environment is the cultured area for shellfish mudflats, its quality will directly affect the survival of shellfish. Shellfish is a filter feeding animal with powerful filtering ability. In recent years, with the rapid development, the mudflat deterioration of the environment threatens shellfish′s living severely. As a result, the shellfish community was changed. Therefore, understanding the resource biomass changes is especially important for policy-makers. The research provides scientific evidence for protecting the marine resources and sustainable development. It discusses the resource and community stability by abundance-biomass curve and size spectra. One point should be noted that the biomass size spectrum（BSS） and normalized biomass size spectra（NBSS） were applied to the shellfish community firstly. In some ways, the BBS method is easier to achieve, in which calculation errors caused by inaccurate shellfish identification may be avoided. In order to understand the marine ecosystems, the fields of application for the BSS theory have been adopted into benthic communities, fish and so on. The species composition, dominance, resource biomass and density and community diversity were studied using data collected from four surveys from May 2016 to February 2017 in Yueqing Bay, Zhejiang Province. The main results showed that 45 shellfish species were identified, which belonged to 12 orders, 25 families and 31genera. The absolute dominant species was Potamocorbula ustulata; the level of resource biomass and density was the highest level in summer, followed by winter, spring and autumn. The average values for species abundance index（D）, species diversity index（H′） and species evenness index（J′） were 3.26, 1.61 and 0.45, respectively, indicating that shellfish community diversity was on a low level. The ABC curve showed that the shellfish community was unstable. The biomass size spectrum was complicated, which dome was controlled by dominant species. Compared with other Chinese offshore areas, it was also different from others results. The slopes of NBSS ranged from-1.5539 to-0.7373, and the intercepts ranged from 16.673 to 21.597. The slope values were lower than those of most other area of Chinese offshore area, and it stood for a lower circulatory efficiency of nutrients in Yueqing Bay. In addition, the intercept values inferred that the production in Yueqing Bay was higher than other Chinese offshore areas. As an ecological research method, bi