北部湾浮游幼虫群落结构及其环境适应性分析

根据1998年2月至1999年5月在北部湾海域按季度进行的4个航次生态、环境综合调查资料,本文研究了北部湾海域浮游幼虫的主要类群及其季节变动。结果表明:北部湾海域浮游幼虫主要有15大类群;其中4类(长尾类幼虫、短尾类幼虫、口足类阿利玛幼虫、蛇尾类长腕幼虫)周年出现,其它为季节性出现。长尾类幼虫、口足类阿利玛幼虫、蛇尾类长腕幼虫、短尾类溞状幼虫、短尾类大眼幼虫及其它短尾类幼虫为优势类群。北部湾浮游幼虫的年丰度变化范围为0.02~7.65ind/m³,均值为0.50ind/m³,四季的丰度为夏季(0.86ind/m³)>春季(0.40ind/m³)>秋季(0.32ind/m³)>冬季(0.12ind/m³)。从春季到冬季整个浮游幼虫密集中心呈逆时针从湾的东北部向西北部海区移动,移至湾的中部后再返至西北部。K优势度曲线分析表明群落多样性由高到低依次为春季>冬季>夏季>秋季,总体上浮游幼虫群落多样性的季节差异不大。典范对应分析结果表明影响浮游幼虫栖息密度的主要因子是水温和pH,其次是盐度、溶解氧。

Community structure and environmental adaptation of the planktonic larvae in Beibu Gulf

Seasonal species composition,abundance variations of the planktonic larvae were investigated during four cruises conducted in the Beibu Gulf,between Feb 1998 and May 1999. A total of 15 groups of planktonic larvae were identified,including Macruran larva,Alima larva,Ophiopluteus larva,Brachyura zoea,Brachyura megalopa and other Brachyura larva,six dominant groups,and other common groups. There were four groups which occurred all year round while the others occurred in some seasons. The results from 4 seasonal cruises suggested that the abundance of planktonic larvae in the Beibu Gulf ranged from 0.02 to 7.65 ind/m³ and averaged 0.50 ind/m³. The average abundance of planktonic larvae was 0.86,0.40,0.32,0.12 ind/m³ in summer,spring,autumn and winter respectively. The density centre was moving anticlockwise from the northeast of the Gulf in spring to the northwest in summer and autumn,then back to the northeast in winter. The K-dominance curves suggested that the community diversity of the planktonic larvae decreased from spring,winter,summer to autumn in sequence,but the range of seasonal variations was not so obvious. And the canonical correspondence analysis (CCA) showed that the abundance of planktonic larvae was affected greatly by the sea water temperature and pH,but less by the salinity and DO.