Grazing impact and prey selectivity of picoplanktonic cells by mixotrophic flagellates in oligotrophic lakes
Grazing impact and prey selectivity of picoplanktonic cells by mixotrophic flagellates in oligotrophic lakes
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DOI：
10.1007/s10750-018-3610-3
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发表时间：
2019-03-01
期刊：
影响因子：
2.6
通讯作者：
Unrein, Fernando
中科院分区：
文献类型：
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作者：
Gerea, Marina;Queimalinos, Claudia;Unrein, Fernando
在低营养环境中，浮游藻类的混合营养可以支配浮游生物的捕食。通过对3种不同的荧光猎物（细菌、picocyanobacteria和pico真核藻类）进行8个实验室放牧实验，比较了两个低营养浅湖（Escondido和Morenito）自然群落中不同混合营养类群的放牧活动和猎物偏好。混合营养鞭毛虫（MF）共8个类群，分别属于5个不同的纲和2个异养鞭毛虫的大小类别。Chesson指数表明，10种原生生物更倾向于picokaryotic bacteria而不是细菌，而pico真核藻类不被任何鞭毛虫摄取。在这两个湖泊中，由于鞭毛虫导致的微浮游生物摄取量约占80%，当考虑到所有鞭毛虫、纤毛虫和轮虫时，它们对总放牧影响的贡献率超过50%。假足霉属（pseudopedpenella spp.）、小黄斑霉属（Chrysochromulina parva, Haptophyceae）和散斑霉属（Dinobryon divergens, Chrysophyceae）是最重要的捕食者，而Plagioselmis lacustris （Cryptophyceae）和Chrysophyceae bb50 μ m的捕食率最低。总的来说，我们的研究结果支持MF是寡营养系统中主要的浮游生物捕食者的观点。此外，我们还得出结论，在低营养环境中，草食是混合营养碳循环的关键过程。
Mixotrophy by planktonic algae can dominate picoplankton predation in oligotrophic environments. We compared the grazing activity and prey preference of different mixotrophic taxa from natural communities of two oligotrophic shallow lakes (Escondido and Morenito) by performing eight laboratory grazing experiments using three different fluorescent prey (bacteria, picocyanobacteria, and picoeukaryotic algae). Eight taxa of mixotrophic flagellates (MF) corresponding to five different Classes, and two size categories of heterotrophic flagellates were distinguished. Chesson index showed that the ten identified protists preferred picocyanobacteria than bacteria, while picoeukaryotic algae were not ingested by any flagellate. In both lakes, MFs were responsible for ca. 80% of the picoplankton ingestiondue to flagellates, and more than 50% of the total grazing impact when considering all flagellates, ciliates, and rotifers. Pseudopedinella spp. (Dictyochophyceae), Chrysochromulina parva (Haptophyceae), and Dinobryon divergens (Chrysophyceae) were the most important predators, while Plagioselmis lacustris (Cryptophyceae) and Chrysophyceae>5 mu m showed the lowest grazing rates. Overall, our findings support the idea of MF being the main picoplankton predators in oligotrophic systems. Besides, we also conclude that herbivory represents a key process in the mixotrophic carbon cycling in oligotrophic environments.