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首页> 外文期刊>Estuarine Coastal and Shelf Science >Temporal and diel cycling of nutrients in a barrier-lagoon complex: Implications for phytoplankton abundance and composition
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Temporal and diel cycling of nutrients in a barrier-lagoon complex: Implications for phytoplankton abundance and composition

机译：泻湖复合体中营养物的时间和狄尔循环：对浮游植物丰度和组成的影响

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摘要

The cycling of nutrients (silicate, nitrate, ammonium and phosphate) in a quasi-pristine barrier-lagoon complex (Louro Lagoon, NW Iberian Peninsula) was studied both in a diel and temporal timescale covering different seasonal conditions. Hydrographical and meteorological conditions exert a major control on the nutrient cycling in the lagoon. From late autumn to early spring the lagoon is characterized by oxic conditions due to significant freshwater inputs and sporadic communication with the sea. In summer, elevated primary production coupled with water stagnancy leads to bottom waters hypoxia and marked diel variation of pH, oxygen and redox potentials. Diel variation of nutrients was only evident when mixing of surface and bottom waters during the night was observed. Temporal changes in nutrients concentrations and their relative abundance were found to induce a clear shift in the phytoplankton composition. In winter, during silicate and nitrate abundance and low phosphate, diatoms predominate. In summer, under hypoxic conditions, sediments take control on the supply of nutrients leading to increased phosphate availability relative to nitrate/ammonium or silicate. Diatoms are then replaced during the summer blooms - linked to low atomic N:P ratios (typically <2) -by flagellates and green algae with minor contributions of cyanophytes and dinoflagellates.
机译：研究了准原始屏障-泻湖复合体（西北伊比利亚半岛卢罗泻湖）中营养物质（硅酸盐，硝酸盐，铵盐和磷酸盐）的循环，涉及了不同季节条件的diel和时间尺度。水文和气象条件对泻湖中的养分循环起主要控制作用。从深秋到初春，由于大量淡水输入和与海的零星交流，泻湖的特征是有氧条件。在夏季，初级生产力的提高加上水的停滞导致底水缺氧，pH，氧气和氧化还原电势的明显变化。仅在夜间观察到地表水和底水混合时，养分的狄尔变化才明显。发现营养物浓度及其相对丰度的时间变化会引起浮游植物组成的明显变化。在冬季，硅酸盐和硝酸盐含量高而磷酸盐含量低时，硅藻占主导地位。在夏季，在缺氧条件下，沉积物控制着养分的供应，从而导致相对于硝酸盐/铵盐或硅酸盐而言，磷酸盐的利用率增加。然后，在夏季开花期间，硅藻被鞭毛虫和绿藻替换，这与低的原子氮磷比（通常小于2）相关，而蓝藻和鞭毛藻的贡献很小。

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