Efficiency of a phytoplankton-based and a bacteria-based food web in a pelagic marine system
Efficiency of a phytoplankton-based and a bacteria-based food web in a pelagic marine system
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DOI：
10.4319/lo.2007.52.1.0121
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发表时间：
2007-01-01
影响因子：
4.5
通讯作者：
Andersson, Agneta
中科院分区：
文献类型：
--
作者：
Berglund, Johnny;Muren, Umut;Andersson, Agneta
利用波罗的海北方海水进行了围隔实验，研究了浮游植物和细菌两种不同食物网的食物网效率。实验中的生物包括细菌、浮游植物、原生动物和中型浮游动物（桡足类）。通过在添加氮和磷（NP）的高光水平下孵育产生基于植物生长素的食物网。通过添加碳、氮和磷（CNP）并在较低的光照水平下孵育，创建了一个基于细菌的食物网。在CNP处理中，细菌占主导地位的生产力（91%），而在NP处理中，浮游植物占主导地位的生产者（74%）。在NP处理的浮游植物群落中占主导地位的自养nanoflagellates。食物网效率，定义为中型浮游动物生产力每基础生产力（浮游植物+细菌），是22%的植物浮游生物为基础的食物网和2%的细菌为基础的食物网。这种差异可以解释为1-2个额外的营养级在细菌为基础的食物网中，碳通过鞭毛虫和纤毛虫到达中型浮游动物之前，而在浮游植物为基础的食物网中，有一个直接的途径从浮游植物到中型浮游动物。中型浮游动物的稳定同位素分析支持了这一结果。我们建议，气候变化，增加降水和河流径流在波罗的海，可能有利于细菌为基础的食物网，从而降低浮游生产力在较高的营养水平。
The food web efficiency in two contrasting food webs, one phytoplankton based and one bacteria based, was studied in a mesocosm experiment using seawater from the northern Baltic Sea. Organisms included in the experiment were bacteria, phytoplankton, protozoa, and mesozooplankton (copepods). A phytoplankton-based food web was generated by incubating at a high light level with the addition of nitrogen and phosphorus (NP). A bacteria-based food web was created by adding carbon, nitrogen, and phosphorus (CNP) and incubating at a lower light level. In the CNP treatment bacteria dominated the productivity (91%), while in the NP treatment phytoplankton were dominant producers (74%). The phytoplankton community in the NP treatment was dominated by autotrophic nanoflagellates. The food web efficiency, defined as mesozooplankton productivity per basal productivity (phytoplankton + bacteria), was 22% in the phytoplankton-based food web and 2% in the bacteria-based food web. This discrepancy could be explained by 1-2 extra trophic levels in the bacteria-based food web where carbon passed through flagellates and ciliates before reaching mesozooplankton, while in the phytoplankton-based food web there was a direct pathway from phytoplankton to mesozooplankton. The results were supported by stable isotope analysis of mesozooplankton. We propose that climate change, with increased precipitation and river runoff in the Baltic Sea, might favor a bacteria-based food web and thereby reduce pelagic productivity at higher trophic levels.