钦州湾秋季和春季浮游动物分布特征及影响因素

为了解钦州湾浮游动物群落的时空分布特征及与主要环境因子的关系,于2014年10月和2015年3月进行了秋季和春季两航次的调查。结果表明:该海湾的浮游动物群落有明显的季节变化。秋季共鉴定出12类87种,其中优势种有太平洋纺锤水蚤(Acartia pacifica)、肥胖三角溞(Evadne tergestina)、亨生莹虾(Lucifer hanseni)、百陶箭虫(Sagitta bedoti)和长尾类幼虫(Macrura larvae);春季共鉴定出11类48种,优势种为中华哲水蚤(Calanus sinicus)和太平洋纺锤水蚤;秋季浮游动物的平均丰度、生物量和多样性指数(528.92个/m~3、110.60 mg/m~3和2.22)均高于春季(48.30个/m~3、61.10 mg/m~3和1.70)。空间分布上,钦州湾外湾浮游动物丰度、生物量和多样性指数的平均值皆高于内湾。多维尺度分析表明,秋季内湾群落相似性较高,春季外湾浮游动物群落相似性较高。相关性分析表明盐度与营养盐是影响钦州湾浮游动物分布的主要环境因子。与2011—2012年数据相比,钦州湾浮游动物群落结构已趋于单一化和小型化,以致生物量明显下降。这一现象主要与钦州湾海水富营养化以及大面积高密度牡蛎养殖有密切的关系。

Distribution patterns and environmental factors of zooplankton in the Qinzhou Bay in spring and autumn

An investigation was conducted in autumn 2014 and spring 2015 in order to learn the temporal and spatial distributions of the zooplankton community, as well as its correlation with environmental factors in Qinzhou Bay. Results show distinct seasonal differences in the community. In autumn, 87 species of zooplankton were detected with 5 dominant species, Acartia pacifica, Evadne tergestina, Lucifer hanseni, Sagitta bedoti, and Macrura larvae; whereas in spring, 48 species were found with 2 species dominant, Calanus sinicus and Acartia pacifica. The average abundance and biomass of zooplankton was greater in autumn (528.92 ind/m³ and 110.60mg/m³,respectively) than in spring (48.30 ind/m³ and 68.64mg/m³,respectively). The Shannon-Wiener diversity index was higher in autumn (2.22) than in spring (1.70).Spatial distribution wise, the abundance, biomass, and diversity of the zooplankton species were higher in the outer bay than that in the inner bay. Furthermore, according to our MDS analysis, composition of the zooplankton community had high similarity in the inner bay in autumn, while the same was observed in the outer bay in spring. The results of the correlation analysis showed that salinity and nutrients were the main environmental factors that affected the zooplankton community. Comparing our results with historical data from 2011 to 2012, we found that the composition of the zooplankton community in Qinzhou Bay showed trends of simplification and had decreased in abundance, which could indicate that high density shellfish culture and eutrophication affected the zooplankton community in Qinzhou Bay.