大亚湾浮游植物群落结构变化及其对水温上升的响应

Changes in phytoplankton community structure in response to water temperature increases in Daya Bay,China

大亚湾核电站1994年建成运行。文章研究大亚湾长时期的生态和环境变化,分析大亚湾浮游植物群落结构变化与环境变化,特别是水温上升的相关性。研究显示,网采浮游植物种类数目在1994年后减少了16种;1994—2004年间,网采浮游植物细胞相对密度以2.13×107m-3·a-1的速率下降,而在1985—2004年间核电站建站的下降速率为2.85×106m-3·a-1;与1982年和1994年相比,1998年的浮游植物群落优势种中细胞个体相对较大的种的比重下降,细胞个体相对较小的种的比重上升;从1985年到2003年,叶绿素a(Chl-a)质量浓度的上升速率为0.069mg·m-3·a-1,而1994年到2003年的上升速率加快,为0.076mg·m3·a-1。与此同时,大亚湾的水温在1994年后明显上升,海水盐度、溶解氧(DO)、化学耗氧量(COD)、和营养盐在1994年后变化幅度也增大。研究结果揭示,核电站热排放导致的水温上升是影响大亚湾浮游植物群落结构的主要因素。

The Daya Bay Nuclear Power Station（DNPS） has been operating scince 1994.This study investigated changes of net-phytoplankton,Chl-a,water temperature,salinity,DO,COD,and nutrients in Daya Bay over two decades.The results showed that the net-phytoplankton abundances decreased by 2.13×107 m3·a-1 during 1994-2004,nearly an order of magnitude greater than during 1985 to 2004when net-phytoplankton decreased by 2.85×106 m3·a-1..The species diversity of net-collected phytoplankton decreased to only 16 species after 1994.The concentration of Chl-a increased by 0.069 mg·m3·a-1 from 1985 to 2003,but the increase was much higher（0.076 mg·m3·a-1） during 1994-2004.When 1982 is compared with 1994,the percentage of relative large cell species decreased,whereas the percentage of relatively small cell species increased by 1998.The water temperature increased after 1994 due to the thermal discharge from the DNPS.The variations of salinity,DO,COD and nutrients got greater ranges after 1994.The results suggest that the increase of water temperature is an important environmental driver changing phytoplankton assemblages in Daya Bay.