莱州湾蟹类的群落结构特征

Community structure of crab in Laizhou Bay

根据2010~2012年渤海莱州湾海域（36°50＇~38°40＇N、118°40＇~120°03＇E）8个航次的蟹类资源底拖网调查结果,对该海域蟹类群落的种类组成及分布、生物量、平均渔获尾数、优势种以及生物多样性等进行了分析和研究。研究结果显示,该海域共发现蟹类20种,隶属于12科、18属,其中三疣梭子蟹（Portunus trituberculatus）和日本蟳（Charybdis japonica）是主要的经济种类,其余大多数为饵料型蟹类,日本蟳为7个航次的优势种,其它优势种类具有季节性差异。生物量组成的季节变化比较明显,生物量和丰度的变化趋势相似,都在2011年夏季达到最大值,冬季最低。各月Shannon-Wiener指数分布在0.63~1.11之间;均匀度指数的范围是0.32~0.73;丰富度指数的范围是0.42~0.78。多元统计分析表明莱州湾内蟹类群落可以划分为2组,胁迫系数（2D stress=0.14）。研究结果表明：1）受山东省休渔政策和增殖放流的影响,大型经济蟹类如三疣梭子蟹的生物量有所回升,多个航次的调查显示其已成为该海域的优势种,但是较上世纪90年代还有较大的差距,依然具有一定的上升空间。2）莱州湾内蟹类多样性水平依然处于较低状态,主要以小型、低质、饵料型的蟹类为主。3）莱州湾蟹类群落的划分较为明显,主要原因是受2011年、2012年三疣梭子蟹放流以及水文环境的影响。

Based on the data of eight bottom trawl surveys on crab resources during 2010 -2012 in Laizhou Bay（36°50＇ - 38°40＇N, 118040＇ -120°03＇E）where 18 survey stations were set, the crab species, distribution, biomass, average catch number,dominant species and diversity were analyzed. Results showed that 20 species of crabs were identified,belonging to 12 families and 18 generas;Portunus trituberculatus and Charybdis japonica were the main economic species and the others were low-value species. Only Charybdis japonica was the dominant species in seven times, while others showed seasonal variations. The seasonal composition of species was obvious. The tendency of the biomass and abundance were similar, reaching to the top in the summer of 2011 and the bottom in the winter of 2011. According to the data , the average Shannon- Wiener index was between 0.63 - 1.11, Pielo＇ s evenness index（J） of the community structure ranged from 0.32 to 0.73,and the Margalef＇ species richness index was between 0.42 - 0.78. Results of the CLUSTER showed that the crab species in Laizhou Bay can be devided into two groups（2D stress = 0.14） according to the biomass of 20 species. The paper showed that： 1 ） Affected by the fishing moratorium and the restocking policy in Shandong Province,the resources of economic species such as Portunus trituberculatus has increased, but it still has much potential to go;2）The crab diversity in Laizhou Bay is still very low, and most of them are small,low-value, baite-type species ;3） Multivariate analysis show that the community structure of crabs in the Laizhou Bay is obvious, one reason is the enhancement and releasing of the Portunus trituberculatus in 2011 and 2012, the other is the effect of hydrological environment in this area.