Processes influencing phytoplankton growth and primary production in shallow temperate estuary Christchurch Harbour, United Kingdom
Processes influencing phytoplankton growth and primary production in shallow temperate estuary Christchurch Harbour, United Kingdom
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发表时间：
2016-11
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通讯作者：
Jiraporn Charoenvattanaporn
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作者：
Jiraporn Charoenvattanaporn
本研究的目的是确定控制浮游植物群落和初级生产力的因素在浅温带河口的基督城港和两个河流系统流入河口。基督城港是位于英格兰南部海岸的一个小型浅水微潮封闭河口。它是由河流斯图尔和汉普郡埃文河，并通过一个狭窄的通道在穆德福德与沿海沃茨交换。从2013年4月至2014年4月，在位于克纳普米尔的汉普郡埃文河和位于Throop的Stour河的最低河流测量站，以及位于河口潮汐极限上方的伊福德桥的另一个测量站，每周进行一次水质和浮游植物群落的密集监测。此外，在同一天，在低潮时，在Mudeford码头的河口入口处进行了一组类似的测量。在2014年春/夏八河口调查进行了每两周的时间间隔与水质，浮游植物丰度和生产的测量在六个站沿着整个河口的横断面。河流浮游植物群落的碳生物量和辅助色素显示出独特的季节演替模式。硅藻群的最大值出现在春季，而绿藻群的最大值出现在夏季。纳米硅藻（2.0 - 20.0？m）、冠盘藻属（Stephanodiscus sp.）浮游植物群落中叶绿素含量最高，达4.4 × 104 cells mL-1，为98.8？g L-1的Stour河在春季时，河流流量减少后，冬季流量高峰。夏季绿藻水华由衣原体属组成，达到7.9 × 104 cells mL-1，并随硅藻春季水华而发生。多变量分析表明，水温，河流流量，硅酸盐和磷酸盐浓度的主要因素控制浮游植物碳生物量在所有的河流研究站点。在Mudeford码头，无机营养盐浓度（硝酸盐，磷酸盐和硅酸盐）一般较低，在减少河流流量期间，但在冬季高流量期间增加。叶绿素a最大值观察到在晚春和秋季和冬季下降的条件相似的河流在Throop和克纳普米尔。浮游植物碳生物量和辅助色素浓度显示了类似的模式。硅藻占主导地位的浮游植物生物量和社区在大部分的采样期，并呈负相关的硅酸盐浓度。甲藻Kryptoperidinium foliaceum观察到高丰度在夏季高盐度值和淡水硅藻Stephanodiscus属。在春季占主导地位。在河口样带调查进行了高潮，高叶绿素“水华”事件（叶绿素高达98？g L-1），在盐度大于30. 0的沃茨中，在河口中部检测到.夏季河流排放量减少导致河口中部盐度较高的水体增加，浮游植物丰度出现相关峰值。在整个夏季，河口浮游植物的不同种群被观察到，甲藻水华主要由K。foliaceum，发生在河口中部，其次是隐藻属。布卢姆。多变量分析表明，辐射衰减系数（k），盐度，氧饱和度，温度，硝酸盐和硅酸盐是控制浮游植物碳生物量的主要因素在样带调查。本研究的结果提供了一个更好的理解的因素控制的生产和分布的河口浮游植物群落在浅温带，基督城港口河口。
The aim of this research project was to identify the factors controlling the phytoplankton community and primary production in the shallow temperate estuary of Christchurch Harbour and the two river systems flowing into the estuary. Christchurch Harbour is a small shallow micro-tidal enclosed estuary situated on the south coast of England. It is fed by the rivers Stour and Hampshire Avon, and exchanges with coastal waters through a narrow channel at Mudeford. An intensive programme of monitoring both the water quality and phytoplankton communities was undertaken at weekly intervals from April 2013 to April 2014 at the lowest river gauging stations on the Hampshire Avon at Knapp Mill and the Stour at Throop plus a further station at Iford Bridge just above the tidal limit of the estuary. In addition a similar set of measurements were made on the same dates at the entrance to the estuary at Mudeford Quay at low tide. During Spring/Summer 2014 eight estuarine surveys were conducted at fortnightly intervals with measurements of water quality, phytoplankton abundance, and production made at six stations along a transect throughout the estuary. The riverine phytoplankton community in terms of carbon biomass and accessory pigments displayed a distinctive pattern of seasonal succession. A diatom group maximum was observed in spring and chlorophyte peak in summer. The nano-sized diatom (2.0 – 20.0 ?m), Stephanodiscus sp., dominated the phytoplankton assemblage, reaching 4.4 × 104 cells mL-1 and a chlorophyll concentration of 98.8 ?g L-1 on the Stour river during spring when river discharge had reduced following the winter flow peak. The summer chlorophyte bloom was composed of Chlamydomonas spp., reaching 7.9 × 104 cells mL-1 and followed the diatom spring bloom. Multivariate analysis revealed that water temperature, river discharge, silicate, and phosphate concentration were major factors controlling phytoplankton carbon biomass at all the river study sites. At Mudeford Quay, inorganic nutrient concentrations (nitrate, phosphate, and silicate) were generally low during periods of reduced river discharge, but increased during the winter high river flow periods. A chlorophyll a maximum was observed during the late spring and decreased during the autumn and winter similar to conditions on the rivers at Throop and Knapp Mill. Phytoplankton carbon biomass and accessory pigment concentration displayed a similar pattern. Diatoms dominated the phytoplankton biomass and community throughout most of the sampling period and were inversely correlated to silicate concentrations. The dinoflagellate Kryptoperidinium foliaceum was observed in high abundance during summer months at high salinity values and the freshwater diatom Stephanodiscus spp. dominated during the spring. During the estuarine transect surveys conducted over high tide, high chlorophyll ‘bloom’ events (chlorophyll up to 98 ?g L-1) were detected in the middle of the estuary in waters of salinity values over 30. Reduced river discharge in summer months led to an increase in higher salinity water in the mid estuary with these associated peaks in phytoplankton abundance. Different populations of estuarine phytoplankton were observed over the course of the summer with dinoflagellate blooms dominated by K. foliaceum, occurring in the mid-estuary followed by Cryptomonas spp. blooms. Multivariate analysis revealed that irradiance attenuation coefficient (k), salinity, oxygen saturation, temperature, nitrate, and silicate were the major factors controlling phytoplankton carbon biomass during the transect surveys. The results of the present study have provided an improved understanding of the factors controlling the production and distribution of estuarine phytoplankton communities in the shallow temperate, Christchurch Harbour estuary.