三门湾微型浮游生物丰度的时空变化特征

The temporal and spatial variation of microplankton abundance in Sanmen Bay

粒径小于20μm的微型浮游生物能迅速响应海洋环境变化,因而在海洋环境监测中起着重要作用。本文应用流式细胞技术研究了三门湾表层与底层海水中微型浮游生物(包括细菌、聚球藻、微型真核生物以及病毒)丰度的时空分布特征,探讨了微型浮游生物丰度与水体理化因子之间的关系。结果表明,三门湾海域微型浮游生物丰度范围:细菌,6.98×10~5~9.84×10!6 cells/mL;聚球藻,1.10×10~3~3.71×10~4 cells/mL;微型真核生物,1.04×10~3~3.75×10~4 cells/mL;病毒,1.01×10~6~3.47×10~7 mL^(-1)。夏、秋两季表层微型浮游生物丰度均高于底层;秋季细菌、聚球藻和病毒丰度低于夏季,但微型真核生物丰度高于夏季;温度是造成微型浮游生物丰度季节差异的主要因素。微型浮游生物丰度的水平分布在夏季无显著规律,但秋季表底层均由内湾向外湾递减。秋季,除底层的细菌外,微型浮游生物丰度水平分布与pH和盐度呈显著负相关,同时与亚硝氮、硝氮、铵氮、叶绿素a呈显著正相关。

Microplankton with cell size less than 20μm are susceptive to environmental alteration,and often employed to study the ecological effect of anthropogenic disturbance in various environment.In this study,we investigated the temporal and spatial patterns of microplankton including bacteria,Synechococcus,microeukaryote and virus by flow cytometry in Sanmen Bay,and explored the driving physicochemical factors.The results showed that the abundance of bacteria,Synechococcus,microeukaryote and virus were 6.98×105-9.84×106 cells/mL,1.10×103-3.71×104 cells/mL,1.04×103-3.75×104 cells/mL and 1.01×106-3.47×107 mL-1,respectively.The abundance of microplankton in surface water was higher than that in bottom both in summer and autumn.Bacteria,Synechococcus and virus were more abundant in summer,but the abundance of microeukaryote had higher abundances in autumn.Among environmental variables detected here,water temperature was the main factor leading to the seasonal variation of microplankton.As to the horizontal distribution patterns,the abundance of microplankton decreased from inner-to outer-bay in autumn,but there was no significant feature in summer.In autumn,the horizontal distribution patterns of microplankton except bacteria in bottom had a significant negative correlation with pH and salinity,and a positive correlation with nitrite,nitrate,ammonium and chlorophyll a.