长江口海域浮游糠虾类生态特征

利用2002—2003年长江口近海（122°00′—123°30′ E，29°00′—32°00′ N）四季调查资料，研究了长江口近海浮游糠虾类多样性、数量波动过程及其与渔场的关系.结果表明：长江口近海共有浮游糠虾14种，秋季10种，春、秋季8种，冬季2种.种类组成季节更替明显，其中从秋季到冬季更替率最高（90.9%），春、夏和秋季多样性指数（H′）值均大于2，冬季为1- 夏季丰度均值最高［234.70 ind·(100 m³)^-1］，秋季为103.34 ind·(100 m³)^-1，春季80.36 ind·(100 m³)^-1，冬季最低12.40 ind·(100 m^3)-1，丰度变化与温度一致.因温、盐适应范围最广，漂浮囊糠虾是春、秋、冬3季的优势种；短额刺糠虾是夏、秋两季的优势种；长额刺糠虾是冬季的优势种各季节优势种对总丰度贡献均较大.夏季短额刺糠虾的聚集强度最高.长江口近海浮游糠虾类对长江口渔场及舟山渔场的形成具有重要意义.

Ecological character of pelagic mysids in Yangtze Estuary of China.

Based on the four seasonal oceanographic cruises investigation data in the Yangtze Estuary (122°00′-123°30′ E, 29°00′-32°00′ N) in 2002-2003, the diversity and abundance dynamics of pelagic mysids as well as their relationships with fishing ground were studied. A total of 14 species were identified, among which, 10 species occurred in autumn, 8 species in spring and summer, and 2 species in winter. Clear seasonal alterations were observed, among which the highest alteration ratio (90.9%) occurred from autumn to winter. Shannon diversity index (H′) in spring, summer and autumn was above 2, and that in winter was 1. Mean abundance was the highest in summer ［234.70 ind·(100 m³)^-1］, followed by in autumn ［103.34 ind·(100 m³)^-1］, spring ［80.36 ind·（100 m³)^-1］, and winter ［12.40 ind·(100 m³)^-1］. The changes in mean abundance were in accordance with the fluctuation of seasonal temperature. Due to the adaptation to a wide range of temperature and salinity, Gastrosaccus pelagicus was dominant in spring, autumn and winter. Acanthomysis brevirostris was dominant in summer and autumn, and A. longirostrisas in winter. The dominant species in each season all made a significant contribution to total abundance. A. brevirostris was observed in large agglomerates in summer. As a kind of fish diet, mysids were of importance in the formation of fishing grounds in the Yangtze Estuary and Zhoushan Islands.