Beyond bulk properties: Responses of coastal summer plankton communities to nutrient enrichment in the northern Baltic Sea
Beyond bulk properties: Responses of coastal summer plankton communities to nutrient enrichment in the northern Baltic Sea
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DOI：
10.4319/lo.2003.48.1.0189
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发表时间：
2003-01
影响因子：
4.5
通讯作者：
R. Lignell;J. Seppälä;P. Kuuppo;T. Tamminen;T. Andersen;I. Gismervik
中科院分区：
文献类型：
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作者：
R. Lignell;J. Seppälä;P. Kuuppo;T. Tamminen;T. Andersen;I. Gismervik
在北方波罗的海沿岸地区春季后开花生长季节进行了所有组合的NH 4和PO 4处理的围隔实验。经验模型用于确定重要的三维处理对主要浮游生物区室的状态和过程变量的影响。此外，稀释实验揭示了藻类生长的主要营养源（外部池，细胞内商店，矿化）和估计浮游植物的生长和摄食损失率。藻类群落的最大（营养充足）生长速率为0.1 - 0.7 d-1。小的（2 - 10 µm）藻类生长迅速（0.5 - 1.5 d-1），而丰富的毛状蓝绿色藻类生长非常缓慢。纤毛虫在最小放牧估计值0.05 - 0.3 d-1时显示出明显的单位增加，并有积极的藻类反应。初始无机N：P比率始终是低（10 µm）粒度级分。在矿物N-和P-耗尽夏末开花的trichal蓝绿色藻类，叶绿素a归一化的14 CO2固定和生长速率的正P响应表明整个藻类组合的生理P缺乏，但只有一个组合的N和P添加诱发藻类生物量的增加。在初夏，低无机N：P比率反映了氮限制，如河口中常见的那样，但后来，该比率的指示值蒸发，显然是因为蓝绿色藻类对气态N2的固定。
Enclosure experiments with all combinations of NH4 and PO4 treatments were carried out in the northern Baltic coastal zone during the post‐spring bloom growth season. Empirical models were used to identify the important 3‐d treatment effects on the state and process variables governing the main plankton compartments. Moreover, dilution experiments revealed the main nutrient sources for algal growth (external pools, intracellular stores, remineralization) and estimated phytoplankton growth and feeding loss rates. Maximal (nutrient‐replete) algal community growth rates were 0.1‐0.7 d‐1. Small (2‐10 µm) algae grew fast (0.5‐1.5 d‐1), whereas the abundant trichal blue‐green algae grew very slowly. Ciliates showed a clear increase in units with positive algal response at minimum grazing estimates of 0.05‐0.3 d‐1. Initial inorganic N: P ratios were consistently low (10 µm) size fractions. During the mineral N‐ and P‐deplete late summer bloom of trichal blue‐green algae, the positive P responses of chlorophyll a‐normalized 14CO2 fixation and growth rates indicated physiological P deficiency of the whole algal assemblage, but only a combined N and P addition evoked an increase in algal biomass. In early summer, low inorganic N: P ratios reflected N limitation, as commonly found in estuaries, but later, the indicative value of this ratio evaporated, evidently because of gaseous N2 fixation by blue‐green algae.