Warming accelerates termination of a phytoplankton spring bloom by fungal parasites
Warming accelerates termination of a phytoplankton spring bloom by fungal parasites
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DOI：
10.1111/gcb.13095
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发表时间：
2016-01-01
影响因子：
11.6
通讯作者：
Van de Waal, Dedmer B.
中科院分区：
文献类型：
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作者：
Frenken, Thijs;Velthuis, Mandy;Van de Waal, Dedmer B.
气候变化预计将有利于全球生态系统中的传染病。在淡水和海洋环境中，寄生虫在控制浮游生物种群动态方面发挥着至关重要的作用。浮游植物种群的感染将导致碳和营养物质转移到寄生虫中，这可能会改变可用于更高营养水平的食物类型。一些浮游植物物种不能被浮游动物食用，而寄生虫终止它们的种群可能会释放出原本无法获得的碳和养分。浮游植物春季水华通常由不能供浮游动物食用的大型硅藻组成，但它们寄生的真菌的游动孢子可能是这种更高营养水平的食物来源。在这里，我们调查了气候变暖对自然浮游植物春季水华真菌感染的影响，并跟踪了浮游动物群落的反应。实验在2014年3月至6月期间暴露在受控季节性温度循环和温暖(+4摄氏度)处理下的约1000L室内中胚层中进行。春季的开花主要是硅藻针叶藻。在感染高峰期，在两种处理中，都有超过40%的针茅种群感染了真菌寄生虫(即寄生虫)。气候变暖并没有影响针叶草水华的发生，但加速了水华的终止。针茅的峰值种群密度在暖化处理中趋于较低。此外，针茅的碳：磷化学计量比在开花期间增加，特别是在对照处理中。这表明对照处理的磷限制增强，这可能限制了壶菌的发育。在温热处理中，轮虫角化病的发生时间提前，并密切关注壶菌感染。因此，脊椎动物的游动孢子可能是角藻的另一种食物来源。因此，我们的研究强调，在理解浮游生物群落对全球变暖的反应时，不仅要考虑营养限制和放牧，还要考虑寄生问题。
Climate change is expected to favour infectious diseases across ecosystems worldwide. In freshwater and marine environments, parasites play a crucial role in controlling plankton population dynamics. Infection of phytoplankton populations will cause a transfer of carbon and nutrients into parasites, which may change the type of food available for higher trophic levels. Some phytoplankton species are inedible to zooplankton, and the termination of their population by parasites may liberate otherwise unavailable carbon and nutrients. Phytoplankton spring blooms often consist of large diatoms inedible for zooplankton, but the zoospores of their fungal parasites may serve as a food source for this higher trophic level. Here, we investigated the impact of warming on the fungal infection of a natural phytoplankton spring bloom and followed the response of a zooplankton community. Experiments were performed in ca. 1000L indoor mesocosms exposed to a controlled seasonal temperature cycle and a warm (+4 degrees C) treatment in the period from March to June 2014. The spring bloom was dominated by the diatom Synedra. At the peak of infection over 40% of the Synedra population was infected by a fungal parasite (i.e. a chytrid) in both treatments. Warming did not affect the onset of the Synedra bloom, but accelerated its termination. Peak population density of Synedra tended to be lower in the warm treatments. Furthermore, Synedra carbon: phosphorus stoichiometry increased during the bloom, particularly in the control treatments. This indicates enhanced phosphorus limitation in the control treatments, which may have constrained chytrid development. Timing of the rotifer Keratella advanced in the warm treatments and closely followed chytrid infections. The chytrids' zoospores may thus have served as an alternative food source to Keratella. Our study thus emphasizes the importance of incorporating not only nutrient limitation and grazing, but also parasitism in understanding the response of plankton communities towards global warming.