莱州湾小拟哲水蚤(Paracalanus parvus)丰度分布周年变动

利用2011年5月?2012年4月(除冰期12月和翌年1?2月外)在渤海莱州湾逐月由底至表垂直拖网(网孔目160 µm)获得的浮游动物样品，开展小拟哲水蚤丰度分布周年季节变动研究。结果显示，小拟哲水蚤季节变化呈单峰型，7?10月份丰度较高，高峰值出现在8月份；水平分布以湾中部偏东侧丰度较集中，其次为湾口站位，湾顶站位为相对低值区。应用Primer 6.0软件中的BIOENV程序分析发现，小拟哲水蚤总丰度的月变化主要受水温影响、特别是1月前的水温，可能还受黄河径流量的间接影响；水平分布则与盐度、水深关系密切。

Annual dynamic distributions of Paracalanus parvus (Copepoda Calanoida) in Laizhou Bay, China

Small copepod Paracalanus parvus is the dominant zooplankton species for early larvae of fishes as food in the critical spawning and nursery habitat of Laizhou Bay, Bohai Sea. Annual dynamic distributions of the species in the bay were studied based on the zooplankton samples that were collected from May 2011 to April 2012 by a net with 50 cm diameter and 160 micron mesh size. In this study, stage-specific abundance of P. parvus from the original sorting was transformed before the multiple analysis including cluster analysis and multidimensional scale. Principal component analysis (PCA) and RELATE modules of BIOENV in software Primer 6.0 were used to seek the best matches of environmental factors that affect distribution of P. parvus. As the most common copepod in Laizhou Bay, P. parvus was observed at all stations during the investigated period. The species was more abundant from July to October compared with other seasons and its abundance peaked in August. By cluster analysis based on the copepod stage-specific abundance, three stations groups were recognized. The one was located on outside of Laizhou Bay near the central Bohai Sea; the second was located to the runoff inlet of the west of the bay; the third was appeared in the transition area of the two mentioned groups before. The abundance of P. parvus reached the highest in the transition group and the lowest in the group outside the runoff inlet. According to the results of BIOENV analysis, the surface water temperature and pH co-regulated seasonal distributions of P. parvus, while seawater salinity and depth had stronger effects on the spatial distributions. The significant correlations between seawater pH and Huanghe River runoff suggest that runoff one month earlier may be a possible indirect factor that affects the temporal variations of the P. parvus.