Estuarine nutrient loading affects phytoplankton growth and microzooplankton grazing at two contrasting sites in Hong Kong coastal waters
Estuarine nutrient loading affects phytoplankton growth and microzooplankton grazing at two contrasting sites in Hong Kong coastal waters
复制标题
河口营养负荷影响香港沿岸水域两个不同地点的浮游植物生长和微型浮游动物的放牧
DOI：
10.3354/meps07888
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发表时间：
2009-01-01
影响因子：
2.5
通讯作者：
Harrison, Paul J.
中科院分区：
文献类型：
--
作者：
Chen, Bingzhang;Liu, Hongbin;Harrison, Paul J.
为了研究河口沃茨营养盐负荷增加对浮游植物生长和微型浮游动物摄食的影响，我们在香港近岸沃茨的2个站位进行了每月稀释实验，并与营养盐状况进行了对比。珠江口附近的西部河口站（WE）受淡水流量的影响最大，而东部海洋站（EO）受南海的影响最大。浮游植物的生长速率往往限制在EO的营养盐，而营养盐限制的浮游植物生长很少发生在WE由于高水平的营养盐输送的珠江，特别是在夏季雨季。较高的叶绿素a，微型浮游动物生物量，浮游植物的生长和微型浮游动物放牧率在WE比EO。然而，叶绿素的增加大大超过了浮游植物生长速率的增加，反映了不同的响应关系，营养盐的可用性。两个站点都观察到了较强的季节性，温度是影响浮游植物生长和微型浮游动物摄食率的重要因素。浮游藻类，尤其是聚球藻，也表现出很强的季节性，夏季丰度比冬季高2 ~ 3个数量级。我们的研究结果证实，在富营养化的海岸环境中，微型浮游动物摄食是浮游植物的主要损失途径，平均占初级生产力的50%以上。
To investigate the effects of enhanced nutrient loading in estuarine waters on phytoplankton growth and microzooplankton grazing, we conducted monthly dilution experiments at 2 stations in Hong Kong coastal waters with contrasting trophic conditions. The western estuarine station (WE) near the Pearl River estuary is strongly influenced by freshwater discharge, while the eastern oceanic station (EO) is mostly affected by the South China Sea. Growth rates of phytoplankton were often limited by nutrients at EO, while nutrient limitation of phytoplankton growth seldom Occurred at WE due to the high level of nutrients delivered by the Pearl River, especially in the summer rainy season. Higher chlorophyll a, microzooplankton biomass, phytoplankton growth and microzooplankton grazing rates were found at WE than at EO. However, the increase in chlorophyll greatly exceeded the increase in phytoplankton growth rate, reflecting different response relationships to nutrient availability. Strong seasonality was observed at both stations, with temperature being an important factor affecting both phytoplankton growth and microzooplankton grazing rates. Picophytoplankton, especially Synechococcus, also exhibited great seasonality at EO, with summer abundances being 2 or 3 orders of magnitude higher than those during winter, Our results confirm that in eutrophic coastal environments, microzooplankton grazing is a dominant loss pathway for phytoplankton, accounting for the utilization of >50%, of primary production on average.