Toxin concentration in Nodularia spumigena is modulated by mesozooplankton grazers
Toxin concentration in Nodularia spumigena is modulated by mesozooplankton grazers
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DOI：
10.1093/plankt/fbp060
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发表时间：
2009-10-01
影响因子：
2.1
通讯作者：
Engstrom-Ost, Jonna
中科院分区：
文献类型：
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作者：
Gorokhova, Elena;Engstrom-Ost, Jonna
节球藻毒素在蓝藻Nodularia spumigena中的生态作用在很大程度上仍然是未知的，促进毒素产生的条件也是如此。本文报道了浮游动物摄食对N. spumigena表示为减少细胞结合的毒素浓度的存在下，桡足类相比，蓝藻在类似的组合没有桡足类。在我们的实验中，N. spumigena在环境浮游生物（< 90 μ m）组合（实验I）或0.2 μ m过滤海水（实验II）中孵育，有和没有桡足类Eurytemora affinis。在类似于28小时孵育后，我们测量了N的变化。spumigena丰度和nodularin浓度，桡足类中Nodularia DNA的出现频率作为对蓝藻的放牧压力的替代，以及E. affinis作为桡足类生长反应的代表。在所有无桡足类处理中，细胞内节球藻毒素浓度比含有桡足类的处理高4倍。在实验I中，桡足类也有一个积极的影响，蓝藻的生长，大概是由于选择性地去除更多的食用藻类物种，从而减少了对营养物质的竞争。在没有替代食物或高桡足类密度的处理中，检测到高频率（18- 80%）的节虫DNA。同时，N.结果表明，在N. spumigena有或没有周围的浮游生物与开始控制相比。这些发现强调需要了解种内相互作用的重要性，节球菌素生产与N。泡沫。
The ecological role of nodularin in cyanobacterium Nodularia spumigena is still largely unknown, as are the conditions that promote toxin production. We report a modulating effect of mesozooplankton grazing on cellular nodularin content in N. spumigena expressed as a decrease in cell-bound toxin concentration in the presence of copepods compared with the cyanobacterium in similar assemblages without copepods. In our experiments, N. spumigena was incubated in an ambient plankton (< 90 mu m) assemblage (Expt I) or in 0.2-mu m filtered seawater (Expt II), with and without the copepod Eurytemora affinis. Following similar to 28-h incubation, we measured the changes in N. spumigena abundance and nodularin concentration, frequency of Nodularia DNA occurrence in copepods as a proxy for grazing pressure on the cyanobacterium and individual RNA content in E. affinis as a proxy for copepod growth response. In all copepod-free treatments, intracellular nodularin concentrations were up to four times higher than in the treatments containing copepods. In Experiment I, the copepods also has a positive effect on the cyanobacterium growth, presumably due to a selective removal of more edible algal species and thus decreased competition for nutrients. Nodularia DNA was detected with high frequencies, 18-80%, increase in treatments with no alternative food or high copepod densities. Simultaneously, no noxious effects of N. spumigena on the copepods were detected as indicated by higher RNA content in copepods exposed to N. spumigena with or without ambient plankton organisms compared with started controls. These findings stress the need to understand the importance of intra-specific interactions for nodularin production in relation to population dynamics of N. spumigena.