School of Geography, Earth and Environmental Science, University of Plymouth, Plymouth, UK.
Sci Total Environ. 2012 Sep 15;434:228-39. doi: 10.1016/j.scitotenv.2011.08.044. Epub 2011 Sep 23.
The Taw Estuary (SW England) is eutrophic as a result of enhanced nutrient inputs from its catchment. However, factors influencing the timing and extent of phytoplankton bloom formation are not fully understood in this system. In this study, high resolution chemical and biological sampling was undertaken in late-winter/spring and summer 2008 in order to gain further insights into bloom dynamics in the Taw Estuary. Temporal variations in chlorophyll a maxima in the upper and middle estuary during summer were controlled by river flow and tidal amplitude, with nutrient limitation probably less important. Concentrations of chlorophyll a were highest during low river flow and neap tides. Increased river flows advected the chlorophyll maximum to the outer estuary, and under highest river discharges, chlorophyll a concentrations were further reduced. This feature was even more pronounced when spring tides coincided with high flows. The main bloom species were the diatoms Asterionellopsis glacialis and Thalassiosira guillardii. Using two multivariate statistical techniques in combination, five distinct physical and biogeochemical states in the Taw estuarine waters were identified. These states can be summarised as: A(1), high chlorophyll a, high temperature, long residence times, nutrient depletion; A(2), strong coastal water influence; B(1), decreasing chlorophyll a, increasing river flow and/or spring tides; B(2), transitional between states A(1) and B(3); B(3), high river flow. It was thus possible to differentiate between contrasting environmental conditions that were either beneficial or detrimental for the development of algal blooms. A conceptual model of diatom - dominated primary production for the Taw Estuary is proposed which describes how physical controls (river flow, tidal state) moderate plankton biomass production in the upper and mid - estuarine regions.
泰湾（英格兰西南部）由于集水区中营养物质的输入增加而呈现富营养化。然而，该系统中仍不完全了解影响浮游植物爆发形成的时间和程度的因素。本研究于 2008 年冬末/春季和夏季进行了高分辨率的化学和生物采样，以便更深入地了解泰湾的浮游植物爆发动态。夏季，在上游和中游河口处叶绿素 a 最大值的时间变化受河流流量和潮汐幅度的控制，营养限制可能不太重要。在低河流量和小潮时，叶绿素 a 的浓度最高。增加的河流流量将叶绿素最大值输送到河口外部，在最高的河流流量下，叶绿素 a 的浓度进一步降低。当大潮与高流量同时发生时，这种特征更为明显。主要的浮游植物物种是硅藻 Asterionellopsis glacialis 和 Thalassiosira guillardii。使用两种多元统计技术相结合，确定了泰湾河口水中的五个不同的物理和生物地球化学状态。这些状态可以概括为：A(1)，高叶绿素 a，高温，长停留时间，营养物质枯竭；A(2)，强烈的沿海水影响；B(1)，叶绿素 a 减少，河流流量和/或大潮增加；B(2)，在状态 A(1)和 B(3)之间过渡；B(3)，高流量。因此，可以区分有利于或不利于藻类爆发发展的不同环境条件。提出了一个以硅藻为主导的泰湾初级生产力的概念模型，该模型描述了物理控制（河流流量、潮汐状态）如何调节上河口和中河口地区浮游生物生物量的产生。
