ANALYSIS ON THE COMMUNITY CHARACTERISTICS OF SHRIMPS IN THE COASTAL SPAWNING GROUND OF SOUTH ZHEJIANG DURING SPRING

On the basis of three surveys carried out by bottom trawl in spring (April, May and June) of 2011 on the coastal spawning ground of South Zhejiang, the community characteristics and its resource status were analyzed by five methods including sweep-area method, analysis of variance, linear correlation analysis, cluster analysis, and non-metric multidimensional scaling. The results showed that 22 species of shrimps were sampled in spring, belonging to sixteen families of nine orders in one class. Among them, sixteen shrimps were sampled in April, belonging to twelve families of eight orders; seventeen shrimps were sampled in May, belonging to thirteen families of seven orders; seventeen shrimps were sampled in June, belonging to thirteen families of eight orders. In the above-mentioned 22 shrimps, there were twelve eurythermal and euryhaline species, eight eurythermal and hyposaline species, and two hyperthermal and hysaline species in spring. There were ten eurythermal and euryhaline species, five eurythermal and hyposaline species, and one hyperthermal and hysaline species in April; ten eurythermal and euryhaline species, five eurythermal and hyposaline species, and two hyperthermal and hysaline species in May; ten eurythermal and euryhaline species, six eurythermal and hyposaline species, and one hyperthermal and hysaline species in June. Both the biomass and the number abundance density indices of shrimps were the highest in June, and the lowest in May. Parapenaeopsis tenella, Palaemon gravieri and Metapenaeus joyneri were the common dominant species of April, May and June. The Shannon-Wiener indices (H) in May and June were significantly different (P0.05). There were negative liner correlation between the Shannon-Wiener (H) index and sea water depth, bottom water salinity and biomass (P0.05), respectively. In shrimp communities of spring in the study area, the community structure was simple. Its species diversity (H) decreased with the increase of the sea water depth, bottom water salinity and biomass, respectively. The eurythermal and euryhaline species occupied the dominant position. In addition, the biomass contribution of the common dominant species to all the three months was more than forty percentage, and same to the number abundance density.