后水湾深水网箱养殖区浮游植物群落季节变化及其与环境因子的关系

基于2018年4月至2019年1月在后水湾深水网箱养殖区及其邻近海域调查的浮游植物和环境因子数据，分析了该海域浮游植物群落的四季变化与环境因子的关系以及深水网箱养殖对环境的影响。结果表明，调查海域鉴定出浮游植物5门65属214种，以硅藻为主；优势种类主要有中肋骨条藻（Skeletonema costatum）、柔弱拟菱形藻（Pseudo-nitzschia delicatissima）、热带骨条藻（Skeletonema tropicum）和细弱海链藻（Thalassiosira subtilis）等，优势种组成存在明显的季节变化；浮游植物细胞丰度和生物多样性指数（丰富度、多样性指数和均匀度）季节差异较为明显，夏、秋季普遍高于冬、春季。根据相似性聚类分析和多维尺度分析结果，浮游植物群落组成季节间差异显著，养殖区和对照点间无显著差异。根据RDA分析结果，温度、盐度和营养盐是影响浮游植物群落结构的主要因子，各种浮游植物对环境因子的响应有所不同。调查期间，后水湾海域水质较好，各季节养殖区与对照点的浮游植物群落组成及环境因子无显著差异，深水网箱养殖未对后水湾的水质及浮游植物产生明显影响。

Seasonal variation of phytoplankton community and its relationship with environmental factors in deep-water cage aquaculture area of Houshui bay

Based on the phytoplankton and environment data collected from the deep-water cage aquaculture area of Houshui bay and its adjacent waters between April 2018 and January 2019, this paper analyzed the seasonal variation of phytoplankton community and its relationship with environmental factors, as well as the impact of deep-water cage aquaculture on the environment. In this research, 214 phytoplankton taxa were identified, which belonged to five phyla and 65 genera, with Bacillariophyta being the main group. The dominant species were Skeletonema costatum, Pseudo-nitzschia delicatissima, Skeletonema tropicum, Thalassiosira subtilis and so on. There were obvious seasonal variations in species composition of the dominant. The phytoplankton abundances and the biodiversity indices (Margalef richness index, Shannon-Wiener diversity and Pielou evenness) were significantly different in season, and they were generally higher in summer and autumn than in winter and spring. The results of Bray-Curtis analysis and non-metric multidimensional scaling analysis showed that the composition of phytoplankton community had significant seasonal differences, but there was no significant difference between the aquaculture area and the control point. Redundancy analysis suggested that the main factors affecting the community structure were temperature, salinity, nutrition, and various phytoplankton respond to these main factors in different ways. The water quality of Houshui bay was fine during the investigation. There was no significant difference in phytoplankton community composition and environmental factors between the aquaculture areas and the control points in each season. Deep-water cage culture had no significant effect on the water quality and phytoplankton in Houshui bay.