美国康涅狄格大学Jessica E. Brandt研究组的最新研究，报道了太平洋鲑鱼在大洲尺度上的营养物质和污染物输送。该研究于2024年10月9日发表于《自然》杂志。

据介绍，迁徙动物携带大量营养物质的移动对受体食物网具有生态效益，但可能被共同运输的污染物所抵消。鲑鱼的洄游产卵是这一过程的典型例子，它们将海洋来源的物质带到内陆生态系统中，刺激当地生产力的提升，但同时也增加了污染物的暴露风险。当前太平洋鲑鱼的数量和生物量比上个世纪更高，这反映了群落结构的显著变化，可能改变了营养物质和污染物的输送比例。

该研究组结合营养物质和污染物的浓度数据，以及40年间每年的太平洋鲑鱼回流情况，量化了群落结构变化如何影响海洋向北美西部淡水生态系统的物质输入。研究发现，鲑鱼每年向淡水输送数吨的营养物质和数千克的污染物。1976-2015年间，鲑鱼回流数量的增加使鲑鱼来源的营养物质和污染物输入量，分别提高了30%和20%。

这种增长主要由寿命较短、在海洋食物网中处于较低营养级的粉鲑主导，其营养物质与污染物的比例最高。由于这种特性，营养物质的输入增速超过了污染物输入的增速，使得鲑鱼输入对生态系统的益处随着时间推移而增加。然而，污染物的负荷量可能仍对部分鲑鱼捕食者构成潜在风险。太平洋鲑鱼的案例揭示了，长期环境变化如何与营养物质和污染物的跨空间传输相互作用，并为研究其他迁徙物种的类似模式提供了参考模型。

附：英文原文

Title: Continental-scale nutrient and contaminant delivery by Pacific salmon

Author: Brandt, Jessica E., Wesner, Jeff S., Ruggerone, Gregory T., Jardine, Timothy D., Eagles-Smith, Collin A., Ruso, Gabrielle E., Stricker, Craig A., Voss, Kristofor A., Walters, David M.

Issue&Volume: 2024-10-09

Abstract: The movement of large amounts of nutrients by migrating animals has ecological benefits for recipient food webs1,2 that may be offset by co-transported contaminants3,4. Salmon spawning migrations are archetypal of this process, carrying marine-derived materials to inland ecosystems where they stimulate local productivity but also enhance contaminant exposure5,6,7. Pacific salmon abundance and biomass are higher now than in the last century, reflecting substantial shifts in community structure8 that probably altered nutrient versus contaminant delivery. Here we combined nutrient and contaminant concentrations with 40years of annual Pacific salmon returns to quantify how changes in community structure influenced marine to freshwater inputs to western North America. Salmon transported tonnes of nutrients and kilograms of contaminants to freshwaters annually. Higher salmon returns (1976–2015) increased salmon-derived nutrient and contaminant inputs by 30% and 20%, respectively. These increases were dominated by pink salmon, which are short-lived, feed lower in marine food webs than other salmon species, and had the highest nutrient-to-contaminant ratios. As a result, the delivery of nutrients increased at a greater rate than the delivery of contaminants, and salmon inputs became more ecologically beneficial over time. Even still, contaminant loadings may represent exposure concerns for some salmon predators. The Pacific salmon example demonstrates how long-term environmental changes interact with nutrient and contaminant movement across large spatial scales and provides a model for exploring similar patterns with other migratory species9.

DOI: 10.1038/s41586-024-07980-2

Source: https://www.nature.com/articles/s41586-024-07980-2