Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
Biomolecules. 2020 Jan 13;10(1):129. doi: 10.3390/biom10010129.
Aquatic insects provide an energy subsidy to riparian food webs. However, most empirical studies have considered the role of subsidies only in terms of magnitude (using biomass measurements) and quality (using physiologically important fatty acids), negating an aspect of subsidies that may affect their impact on recipient food webs: the potential of insects to transport contaminants (e.g., mercury) to terrestrial ecosystems. To this end, I used empirical data to estimate the magnitude of nutrients (using physiologically important fatty acids as a proxy) and contaminants (total mercury (Hg) and methylmercury (MeHg)) exported by insects from rivers and lacustrine systems in each continent. The results reveal that North American rivers may export more physiologically important fatty acids per unit area (93.0 ± 32.6 Kg Km year) than other continents. Owing to the amount of variation in Hg and MeHg, there were no significant differences in MeHg and Hg among continents in lakes (Hg: 1.5 × 10 to 1.0 × 10 Kg Km year; MeHg: 7.7 × 10 to 1.0 × 10 Kg Km year) and rivers (Hg: 3.2 × 10 to 1.1 × 10 Kg Km year; MeHg: 3.3 × 10 to 8.9 × 10 Kg Km year), with rivers exporting significantly larger quantities of mercury across all continents than lakes. Globally, insect export of physiologically important fatty acids by insect was estimated to be ~43.9 × 10 Kg year while MeHg was ~649.6 Kg year. The calculated estimates add to the growing body of literature, which suggests that emerging aquatic insects are important in supplying essential nutrients to terrestrial consumers; however, with the increase of pollutants in freshwater systems, emergent aquatic insect may also be sentinels of organic contaminants to terrestrial consumers.
水生昆虫为河岸食物网提供能量补助。然而，大多数实证研究仅从数量（使用生物量测量）和质量（使用生理上重要的脂肪酸）方面考虑补助的作用，而忽略了补助可能影响其对受纳食物网影响的一个方面：昆虫将污染物（例如汞）运送到陆地生态系统的潜力。为此，我使用实证数据来估算昆虫从各大洲的河流和湖泊系统中输出的养分（使用生理上重要的脂肪酸作为替代物）和污染物（总汞 (Hg) 和甲基汞 (MeHg)）的数量。结果表明，北美的河流每单位面积可能输出更多的生理上重要的脂肪酸（93.0 ± 32.6 Kg Km year）。由于 Hg 和 MeHg 的变化量，湖泊（Hg：1.5 × 10 至 1.0 × 10 Kg Km year；MeHg：7.7 × 10 至 1.0 × 10 Kg Km year）和河流（Hg：3.2 × 10 至 1.1 × 10 Kg Km year；MeHg：3.3 × 10 至 8.9 × 10 Kg Km year）中各大陆之间的 MeHg 和 Hg 没有显着差异，河流从所有大陆向陆地生态系统输出的汞的数量明显大于湖泊。全球范围内，昆虫输出的生理上重要的脂肪酸估计约为 43.9 × 10 Kg 年，而 MeHg 约为 649.6 Kg 年。计算得出的估计数增加了越来越多的文献，这些文献表明新兴的水生昆虫对为陆地消费者提供必需营养物质很重要；但是，随着淡水中污染物的增加，新兴的水生昆虫也可能成为陆地消费者有机污染物的哨兵。
