WasserCluster - Biologische Station Lunz, Inter-university Center for Aquatic Ecosystem Research, Dr. Carl Kupelwieser Promenade 5, A-3293 Lunz am See, Austria.
WasserCluster - Biologische Station Lunz, Inter-university Center for Aquatic Ecosystem Research, Dr. Carl Kupelwieser Promenade 5, A-3293 Lunz am See, Austria.
Protist. 2020 Nov;171(5):125768. doi: 10.1016/j.protis.2020.125768. Epub 2020 Sep 16.
Microbial parasites have only recently been included in planktonic food web studies, but their functional role in conveying dietary energy still remains to be elucidated. Parasitic fungi (chytrids) infecting phytoplankton may constitute an alternative trophic link and promote organic matter transfer through the production of dissemination zoospores. Particularly, during proliferation of inedible or toxic algal species, such as large Cyanobacteria fostered by global warming, parasites can constitute an alternative trophic link providing essential dietary nutrients that support somatic growth and reproduction of consumers. Using phytoplankton-parasites associations grown under laboratory controlled conditions we assessed the fatty acids and biochemical composition of species with different nutritional quality and followed the metabolic pathway from the algal host and their parasites zoospores using compound-specific stable isotope analysis. This study demonstrated that chytrids are trophic upgraders able to retain essential nutrients that can be transferred to upper trophic levels both in terms of organic matter quantity and nutritional quality. Through the production of zoospores, nutritionally important long-chain polyunsaturated fatty acids that can be consequently assimilated by consumers. We conclude that parasitism at the base of aquatic food webs may represent a crucial trophic link for dietary nutrients and essential biomolecules alternative to herbivory or bacterivory, which can be particularly crucial during the proliferation of inedible or nutritionally inadequate algal species fostered by climate change.
微生物寄生虫最近才被纳入浮游生物食物网研究中，但它们在传递饮食能量方面的功能作用仍有待阐明。感染浮游植物的寄生真菌（壶菌）可能构成另一种营养联系，并通过产生传播游动孢子来促进有机物质的转移。特别是在可食用或有毒藻类物种（如全球变暖促进的大型蓝藻）大量繁殖期间，寄生虫可以构成另一种营养联系，为消费者的身体生长和繁殖提供必需的饮食营养。本研究使用在实验室控制条件下生长的浮游植物-寄生虫联合体，评估了具有不同营养质量的物种的脂肪酸和生化组成，并使用化合物特异性稳定同位素分析跟踪从藻类宿主及其寄生虫游动孢子的代谢途径。本研究表明，壶菌是营养升级者，能够保留可以通过游动孢子转移到上层营养级别的必需营养物质，无论是在有机物数量还是营养质量方面。通过产生游动孢子，传递营养的长链多不饱和脂肪酸可以被消费者随后同化。我们的结论是，水生食物网底部的寄生现象可能代表了饮食营养和替代草食性或细菌食性的重要生物分子的关键营养联系，在气候变化促进的不可食用或营养不足的藻类物种大量繁殖期间，这种联系可能尤为重要。
