海南西北部近岸海域浮游动物群落结构与环境因子的关系

根据2016年11月至2017年8月4个季度的调查资料,采用冗余分析模型,分析报道了海南西北部近岸海域浮游动物的种类组成、丰度和生物量、群落结构与环境因子之间的关系。结果表明,4个季度共鉴定浮游动物7门113属215种,种类数秋季最多(134种),丰度均值冬季最高(152.43 ind/m~3),生物量均值冬季最高(263.68 mg/m~3);浮游动物种类组成、丰度和生物量与水深、浮游植物丰度、透明度、表层水温、表层溶解氧和表层总氮显著相关(P0.05),其中水深是关键环境因子,其影响随季节变化而变化;生态类群具有一定的生态分化现象,春季、夏季热带暖水种占优,秋季、冬季近岸暖水种占优,各季节生态类群受控的环境因子各异。

Relationship between the zooplankton community structure and environmental factors offshore of northwest Hainan Island, China

To understand the community structure of zooplankton offshore of northwest Hainan Island and explore the relevant environmental factors affecting their distribution, we conducted seasonal investigations in sites offshore of northwest Hainan Island in November 2016 and February, May, and August 2017. A redundancy analysis model was used to analyze the relationship between the community structure and environmental factors. Nonmetric multidimensional scaling ordination analysis was applied to test the differences between the communities. Furthermore, ANOSIM similarity testing was used to analyze the differences among the communities. A total of 215 species, belonging to 113 genus and 7 phyla, were identified, among which 134 species were present in autumn and 94 in summer. The number of identified species was relatively close between winter (113 species) and spring (111 species). The seasonal differences in the average abundance of zooplankton was significant, being highest in winter (152.43 ind/m³) and lowest in spring (64.76 ind/m³). The seasonal differences in the average biomass of zooplankton was also significant, being highest in winter (263.68 mg/m³) and lowest in spring (59.13 mg/m³). The RDA showed that the water depth, phytoplankton abundance, transparency, surface temperature, surface dissolved oxygen, and surface total nitrogen have significant correlations with the community structure of zooplankton. Among these environmental factors, the water depth was the key factor, which affected the variation in the zooplankton community structure according to the seasons. Tropical warm water species were the dominant groups in spring and summer, while offshore warm water species were dominant in autumn and winter, suggesting an ecological differentiation among ecological groups. This was mainly caused by the flow direction of the current in Beibu Bay. Compared with the same latitude (waters of Cheng Mai and Dongzhai Harbor) and a lower latitude (Sanya Bay and waters of Wanning), higher amounts of zooplankton species were found offshore of northwest Hainan Island. When compared with Beibu Bay and the coastal waters of the northern South China Sea, the number of zooplankton species in this study was lower. However, the changing tendencies of dominant groups, ecological communities, and seasonal variation characteristics were consistent among these areas.