Department of Fundamental Sciences and Group for Interuniversity Research in Limnology and aquatic environment (GRIL), Université du Québec à Chicoutimi, Saguenay, Québec, Canada.
National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada.
Sci Rep. 2017 Sep 14;7(1):11543. doi: 10.1038/s41598-017-10956-0.
Shortening winter ice-cover duration in lakes highlights an urgent need for research focused on under-ice ecosystem dynamics and their contributions to whole-ecosystem processes. Low temperature, reduced light and consequent changes in autotrophic and heterotrophic resources alter the diet for long-lived consumers, with consequences on their metabolism in winter. We show in a survival experiment that the copepod Leptodiaptomus minutus in a boreal lake does not survive five months under the ice without food. We then report seasonal changes in phytoplankton, terrestrial and bacterial fatty acid (FA) biomarkers in seston and in four zooplankton species for an entire year. Phytoplankton FA were highly available in seston (2.6 µg L) throughout the first month under the ice. Copepods accumulated them in high quantities (44.8 µg mg dry weight), building lipid reserves that comprised up to 76% of body mass. Terrestrial and bacterial FA were accumulated only in low quantities (<2.5 µg mg dry weight). The results highlight the importance of algal FA reserve accumulation for winter survival as a key ecological process in the annual life cycle of the freshwater plankton community with likely consequences to the overall annual production of aquatic FA for higher trophic levels and ultimately for human consumption.
缩短湖泊冬季冰盖持续时间突出表明，迫切需要研究重点放在冰下生态系统动态及其对整个生态系统过程的贡献上。低温、光照减少以及由此导致的自养和异养资源的变化改变了长寿消费者的饮食，从而对它们在冬季的新陈代谢产生影响。我们在一项生存实验中表明，在没有食物的情况下，北方湖泊中的桡足类 Leptodiaptomus minutus 在冰下无法存活五个月。然后，我们报告了整个一年中悬浮物中和四个浮游动物物种中浮游植物、陆地和细菌脂肪酸 (FA) 生物标志物的季节性变化。在冰下的第一个月，浮游植物 FA 在悬浮物中高度可用（2.6 µg L）。桡足类大量积累它们（44.8 µg mg 干重），建立了脂质储备，占体重的 76%。陆地和细菌 FA 仅以低量积累（<2.5 µg mg 干重）。研究结果强调了藻类 FA 储备积累对冬季生存的重要性，这是淡水浮游生物群落年度生命周期中的一个关键生态过程，可能对更高营养级别的水生 FA 的整体年度产量产生影响，最终对人类消费产生影响。
