东海中南部外海虾类群落结构特征分析

依据2006年5月（春）、8月（夏）、11月（秋）和2007年2月（冬）在东海中南部外海（26°00′N-28°30′N ，126°00′E以西）海域虾类资源调查资料，分析了虾类的种类组成、优势度、多样性等群落结构特征。共采获虾类32种，隶属于11科22属，优势种有长角赤虾（Metapenaeopsis longirostris）、戴氏赤虾（Metapenaeopsis dalei）、高脊管鞭虾（Solenocera alticarinata）、东海红虾（Plesionika izumiae）、九齿扇虾（Ibacus novemdentatus）、假长缝拟对虾（Parapenaeus fissuroides）、凹管鞭虾（Solenocera koelbeli）、大管鞭虾(Solenocera crassicornis)、哈氏仿对虾(Parapenaeopsis hardwickii)和中华管鞭虾(Solenocera crassicornis)，其中长角赤虾、戴氏赤虾、东海红虾、假长缝拟对虾和哈氏仿对虾是主要优势种，常见种是须赤虾(Metapenaeopsis barbata)、日本囊对虾(Penaeus japonicus)、脊单肢虾(Sicyonia cristata)、葛氏长臂虾(Palaemon gravieri)、日本鼓虾(Alpheus japonicus)、全刺拟长额虾(Parapandalus spinipes)和齿额红虾(Plesionika dentirostris)。东海中南部外海大部分虾类属于高温高盐生态群落，虾类丰度空间分布呈现120m等深线以西的站位高，120m等深线以东站位低的特征，但是秋季和冬季的生物丰度普遍减小，冬季整个海域的虾类丰度基本达到全年的最低值。不同季节中，秋季种类最多（22种），其次是冬季（20种），春、夏季较少（分别为17种、18种）；Margalef指数(D)和Shannon-Wiener多样性指数 以夏秋季较高，春冬季较低，整个海区四个季节的均匀性指数 较为稳定。从空间分布来看，4个季节中东海中南部外海120m等深线以西站位多样性指数高于120m等深线以东的站位；运用聚类和非线性多维标序对群落结构的相似性进行分析，结合水深等环境因子，表明东海中南部外海虾类可分为两个群聚类型，即深海域群聚和外缘群聚。

Community characteristics of shrimps in the offshore waters of the mid-southern East China Sea

Based on the data of the shrimp resources sampled by single trawler as investigation boat in 18 stations in the offshore waters of the Mid-Southern East China Sea (26°00'N--28°30'N, 121°00'E--126°00'E) in May, August, November, 2006 and February, 2007, total catch from each trawler was counted and identified to species in taxonomy, and the spatial variation of the shrimp species composition, index of relative importance (IRI), the diversity and similar characteristics of the community structure were analyzed. 32 species of shrimp were caught in this survey, which belonged to 22 families under 11 genera. Comparison of the amounts of various species in different seasons : there are 22 species in the autumn which are the most; 20 species in winter, 17 and 18 species in the spring and the summer respectively. According to the standard of index of relative importance (IRI) (the species with IRI above 1000 were regarded as the dominant species in this paper), there were 10 dominant species: Metapenaeopsis longirostris, Metapenaeopsis dalei, Solenocera alticarinata , Plesionika izumiae , Ibacus novemdentatu , Parapenaeus fissuroides , Solenocera koelbeli , Solenocera crassicornis, Parapenaeopsis hardwickii and Solenocera crassicornis, and 5 of them were major dominant species which were Metapenaeopsis longirostris, Metapenaeopsis dalei, Plesionika izumiae, Parapenaeus fissuroides and Parapenaeopsis hardwickii. Defined the ones with IRI values ranging from 100 to 1000 as common species, we got 7: Metapenaeopsis barbata, Penaeus japonicus, Plesionika dentirostris, Palaemon gravieri, Alpheus japonicus, Parapandalus spinipes and Sicyonia cristata. The abundance of the dominant species was varied with seasons. For example, 5 were in May: Metapenaeopsis longirostris, Metapenaeopsis dalei, Parapenaeopsis hardwickii, Solenocera alticarinata and Plesionika izumiae, 89. 15% of the total catch and 92. 14% of the total individuals. In August, there were 7 dominant species: Metapenaeopsis dalei, Plesionika izumiae, Metapenaeopsis longirostris, Parapenaeus fissuroide,Solenocera crassicornis, lbacus novemdentatus and Solenocera alticarinata, 91.82% of the total catch and 95.05% of the total individuals. In November, the number of dominant species increased to 8 : Metapenaeopsis longirostris, Plesionika izumiae, Parapenaeus fissuroides, Metapenaeopsis dalei, Solenocera crassicornis, Ibacus novemdentatus, Solenocera koelbeli and Solenocera alticarinata, occupying 95.31% and 97.56% of the total catch individuals, respectively. In February, the number reduced to 5 : Metapenaeopsis longirostris, Parapenaeus fissuroicles, Metapenaeopsis dalei, Solenocera koelbeli and Plesionika izumiae, 88.76% and 94. 93% respectively. Based on their adaptability to habitats, all recorded species of shrimps were categorized into the hyperthermal and hysaline community in the Mid-Southern East China Sea. The stations with high abundance were mainly located in the west of the 120m isobaths, and gradually lower toward the autumn to winter, while it reached the lowest in winter. Margalef index (D) and Shannon-Wienner index (H') were higher in summer and autumn than those in winter and spring, Pielou' s evenness index (J') in the offshore waters of the Mid-Southern East China Sea was stable through every season. The result indicated that the diversity index west of the 120m isobaths was higher than in the east. By hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) assisted analyzing, the types of shrimp assemblage determined by influential factor such as aquatic system, water mass and salinity etc. in the East China Sea in spring were also discussed in the article, two main assemblages were identified in the offshore waters of the Mid-Southern East China Sea, which were deeper costal shrimp assemblage and out shelf sea shrimp assemblage.