东海中南部外海蟹类群落结构特征

2006年5月（春）、9月（夏）、11月（秋）和2007年2月（冬）对东海中南部外海（26°00′—28°30′ N，121°00′—126°00′ E）海域蟹类资源进行调查，分析了蟹类的种类组成、优势度、多样性和生物量等群落结构特征.结果表明：本次调查共鉴定蟹类49种，隶属于12科30属；春、秋季，调查海域蟹类种数呈北部高、南部低的特征，夏季各站位的蟹类种数分布较均匀，冬季该海域南北地区蟹类种数的差异较小，但调查海域外侧站位的种数较多；调查海域蟹类的优势种为13种，主要包括：双斑蟳、卷折馒头蟹、武士蟳、细点圆趾蟹、长手隆背蟹、光掌蟳和银光梭子蟹等；调查海域夏季的蟹类多样性指数较低，其他3个季节的差别不大；调查海域蟹类平均渔获资源量为5197.62 g·h^-1，夏季（8830.79 g·h^-1）﹥春季（4877.50 g·h^-1）﹥秋季（4268.30 g·h^-1）﹥冬季（2813.87 g·h^-1）.东海中南部外海蟹类可划分为3个生态群落，即广温广盐生态群落、高温广盐生态群落、高温高盐生态群落.

Structural characteristics of crab communities in offshore waters of mid-southern East China Sea

The crab resources in the offshore waters of mid-southern East China Sea(26°00'-28°30' N,121°00'-126°00' E)were investigated in May(spring),August(summer),November(autumn)2006 and February(winter)2007,with the characteristics of their community structure,including species composition,index of relative importance(IRI),diversity,and biomass analyzed.A total of 49 species were identified,belonging to 30 genera and 12 families.In both spring and autumn,the crab species number was higher in northern than in southern part of the Sea; in summer,it had a relatively uniform distribution; while in winter,less difference was observed between the southern and northern parts of the Sea,and the crabs were mainly concentrated in the exterior areas.A total of 13 dominant species(IRI＞1000)with Charybdis bimaculata,Calappa lophos,Charybdis miles,Ovalipes punctatus,Carcinoplax longimana,Charybdis riversandersoni,and Portunus argentatus as the representatives appeared all the year round.The diversity index of the crabs was lower in summer,but had no significant difference among the other three seasons.The catching mass of the crabs in the investigated sea area was averagely 5197.62 g·h~(-1),being 8830.79 g·h~(-1) in summer ＞4877.50 g·h~(-1) in spring ＞ 4268.30 g·h~(-1) in autumn ＞ 2813.87g·h~(-1) in winter.The crabs in the offshore waters of mid-southern East China Sea could be categorized as 3 ecological communities,i.e.,eurythermal and eurysaline,hyperthermal and eurysaline,and hyperthermal and hysaline.