Guangdong Basic Research Center of Excellence for Ecological Security and Green Development, Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou 510006, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Sci Total Environ. 2024 Jul 1;932:172879. doi: 10.1016/j.scitotenv.2024.172879. Epub 2024 Apr 30.
Omega-3 polyunsaturated fatty acids (ω3-PUFA) are central to the growth and reproduction of aquatic consumers. Dissolved nutrients in aquatic ecosystems strongly affect algal taxonomic composition and thus the production and transfer of specific ω3-PUFA to consumers at higher trophic levels. However, most studies were conducted in nutrient-poor, oligotrophic lakes, leading to an insufficient understanding of how water nutrients affect algal ω3-PUFA and their trophic transfer in consumers in highly eutrophic lakes. We conducted a field investigation in a highly eutrophic lake and collected basal food sources (phytoplankton, periphyton and macrophytes) and aquatic consumers (invertebrates, zooplankton and fish), and measured their fatty acid (FA) composition. Our results showed that periphyton and phytoplankton were both important sources of ω3-PUFA supporting the highly eutrophic lake food web. High water nutrient levels led to low ω3-PUFA levels in phytoplankton and periphyton, resulting in decreased nutritional quality. Consequently, ω3-PUFA of invertebrates and zooplankton reflected variations in ω3-PUFA of phytoplankton and periphyton, respectively. The ω3-PUFA levels of fish decreased as phytoplankton and periphyton ω3-PUFA decreased. Among fish, the Redfin Culter (Cultrichthys erythropterus) and Bar Cheek Goby (Rhinogobius giurinus) exhibited significantly higher levels of EPA and DHA compared to the Pond Loach (Misgurnus anguillicaudatus), which may have been caused by their different feeding modes. Decreases in the ω3-PUFA levels of basal food sources may be one of the causes leading to the reduction of trophic links in aquatic food webs. Our study elucidated the sources and fate of ω3-PUFA in highly eutrophic lakes, complemented previous studies in oligo- and mesotrophic lakes, and emphasized the role of high-quality food sources. Our results offer new perspectives for the conservation and management of highly eutrophic lake ecosystems.
ω3 多不饱和脂肪酸（ω3-PUFA）是水生消费者生长和繁殖的核心。水生态系统中的溶解养分强烈影响藻类的分类组成，从而影响特定 ω3-PUFA 向更高营养级消费者的生产和转移。然而，大多数研究都是在贫营养、寡营养的湖泊中进行的，这导致人们对水营养如何影响富营养湖泊中藻类的 ω3-PUFA 及其在消费者中的营养转移的了解不足。我们在一个富营养化湖泊中进行了实地调查，收集了基础食物源（浮游植物、周丛生物和大型植物）和水生消费者（无脊椎动物、浮游动物和鱼类），并测量了它们的脂肪酸（FA）组成。我们的结果表明，周丛生物和浮游植物都是支持富营养化湖泊食物网的 ω3-PUFA 的重要来源。高水体养分水平导致浮游植物和周丛生物中的 ω3-PUFA 水平较低，从而降低了营养价值。因此，无脊椎动物和浮游动物的 ω3-PUFA 分别反映了浮游植物和周丛生物的 ω3-PUFA 的变化。鱼类的 ω3-PUFA 水平随着浮游植物和周丛生物的 ω3-PUFA 减少而降低。在鱼类中，红鳍鲫（Cultrichthys erythropterus）和须唇重唇鱼（Rhinogobius giurinus）的 EPA 和 DHA 水平明显高于泥鳅（Misgurnus anguillicaudatus），这可能是由于它们不同的摄食方式。基础食物源 ω3-PUFA 水平的降低可能是导致水生食物网营养联系减少的原因之一。我们的研究阐明了富营养化湖泊中 ω3-PUFA 的来源和命运，补充了以前在寡营养和中营养湖泊中的研究，并强调了高质量食物源的作用。我们的研究结果为富营养化湖泊生态系统的保护和管理提供了新的视角。
