大亚湾夏季浮游植物群落结构的长期变化及其与环境因子的关系

本文分析了1999?2017年大亚湾夏季浮游植物群落结构的长期变化及其与环境因子的关系，结果显示，大亚湾海域海水温度呈显著下降趋势，盐度呈显著上升趋势；溶解无机氮浓度出现较大幅度提升，2008?2017年间大亚湾溶解无机氮浓度平均值比1999?2007年提升了72.73%；大亚湾浮游植物种类数变化趋势不明显，主要优势种没有发生明显变化，柔弱伪菱形藻（Pseudonitzschia delicatissima）为区域第一优势种，其次为中肋骨条藻（Skeletonema costatum）；浮游植物总丰度、硅藻丰度、甲藻丰度以及主要种类中的柔弱伪菱形藻、中肋骨条藻和叉角藻（Ceratium furca）丰度均呈现显著上升趋势；浮游植物生物多样性指数（H′）和均匀度（J）均呈下降趋势。人类活动所引起的溶解无机氮浓度大幅升高以及外海水入侵加强所引起的海水温度降低和盐度上升导致了浮游植物丰度的上升、优势种的单一化和生物多样性指数的下降。

Long-term changes of phytoplankton community structure with relation to environmental factors in the Daya Bay in summer

Long-term changes of phytoplankton community structure with relation to environmental factors in the Daya Bay in summer between 1999 and 2017 were investigated. The results showed that seawater temperature showed a significant decreasing trend, while salinity increased significantly. During the period 2008 to 2017, the dissolved inorganic nitrogen (DIN) annual mean concentration increased by 72.73% relative to 1999 to 2007. Trend of phytoplankton species number and dominant species were not significant, Pseudonitzschia delicatissima was overwhelmingly dominant followed by Skeletonema costatum. The abundance of total phytoplankton, diatoms, dinoflagellates, and some dominant species (Pseudonitzschia delicatissima, Skeletonema costatum, Ceratium furca) significantly increased during the study period in the Daya Bay. Species diversity and evenness indices showed downward trends. The analysis showed that the increased DIN concentration induced by human activities and seawater temperature and salinity changes were the main reasons for long-term changes of phytoplankton community structure in the Daya Bay in summer.