海南海域四个地区浮游植物群落结构及环境驱动机制分析
Community Structure of Phytoplankton and Environmental Driving Mechanisms in Four Coastal Regions of Hainan

浮游植物是热带近岸海域初级生产力的主要贡献者，其群落结构对营养盐变化具有高度敏感性。本研究在海南万宁、文昌、东方与临高四个典型海区共12个站位开展同步采样，获取浮游植物种类组成、密度以及TN、TP、$N{H}_4^{+}$ 与COD等水质理化因子。通过NMDS、PERMANOVA、RDA与SIMPER等多元统计方法分析群落结构差异及其环境驱动机制，并采用Shannon指数和物种丰富度评估群落多样性。结果表明，四地区浮游植物群落在空间上存在显著差异(PERMANOVA, p < 0.05)，硅藻为绝对优势类群。营养盐梯度，尤其是TN与$N{H}_4^{+}$ ，是影响群落变化的主要环境因子。SIMPER分析显示，中肋骨条藻、热带骨条藻及奇异棍形藻等硅藻对区域群落差异贡献最高。多样性分析显示物种丰富度差。
Phytoplankton are major contributors to primary productivity in tropical coastal ecosystems, and their community structure is highly sensitive to changes in nutrient conditions. In this study, synchronous sampling was conducted at 12 stations across four typical coastal regions of Hainan Island, including Wanning, Wenchang, Dongfang, and Lingao. Phytoplankton species composition and cell density were investigated, together with key physicochemical parameters such as total nitrogen (TN), total phosphorus (TP), ammonium ($N{H}_4^{+}$ ), and chemical oxygen demand (COD). Non-metric multidimensional scaling (NMDS), permutational multivariate analysis of variance (PERMANOVA), redundancy analysis (RDA), and similarity percentage analysis (SIMPER) were applied to examine spatial differences in phytoplankton community structure and to identify major environmental drivers. Shannon diversity index and species richness were calculated to assess community diversity. The results showed significant spatial differences in phytoplankton community composition among the four regions (PERMANOVA, p < 0.05), with diatoms as the dominant group. Nutrient gradients, particularly TN and $N{H}_4^{+}$ , were identified as the primary environmental factors influencing community variation. SIMPER analysis indicated that several diatom species, including Skeletonema costatum, Skeletonema tropicum, and Thalassionema nitzschioides, contributed most to regional community differences. Species richness did not differ significantly among regions, whereas