Mercury Elevator in Lakes: A Novel Vector of Methylmercury Transfer to Fish via Migratory Invertebrates,Environmental Science & Technology Letters

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Mercury Elevator in Lakes: A Novel Vector of Methylmercury Transfer to Fish via Migratory Invertebrates
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2020-06-22 , DOI: 10.1021/acs.estlett.0c00446
Britt D. Hall ₁ , Tyler P. Cobb ₁ , Mark D. Graham ₁ , Raymond H. Hesslein ₂ , Karen A. Kidd ₃ , Richard Vogt _{1,

4} , Peter R. Leavitt _{1,

4,

5}

Affiliation

Fisheries in highly productive prairie lakes of Canada and the United States frequently have fish consumption advisories due to elevated mercury concentrations. This occurrence is unexpected because such alkaline lakes often exhibit lower methylmercury (MeHg) concentrations in basal trophic levels than those expected in less productive basins with circumneutral pH. As sources of MeHg to fish are largely dietary, components of the food web are expected to be critical controls of the transfer of MeHg to fish. Here, we investigated how Leptodora kindtii, a large (1.5 cm) translucent predatory invertebrate that exhibits pronounced diel vertical migration (in sediments by day, upper water column by night), plays a key role in regulating the contamination of fish with MeHg in a well-studied, eutrophic, prairie lake in western Canada. Estimates of diel fluxes of invertebrate biomass and MeHg revealed that migratory adult Leptodora, but not other adult zooplankton or juvenile Leptodora, acted as a vector, uniquely transferring MeHg from presumptive deepwater sites of methylation to pelagic fish communities. This cryptic process suggests that piscivorous fish may experience greatly elevated exposure to MeHg even in circumstances when biogeochemical features, MeHg sources, and daytime food-web configuration suggest that trophic transfers should be minimal.

中文翻译：

湖泊中的汞电梯：通过迁移性无脊椎动物将甲基汞转移到鱼类的新型载体

由于汞浓度升高，加拿大和美国高产草原湖泊的渔业经常有鱼类消费建议。发生这种情况是出乎意料的，因为这种碱性湖泊的营养级水平通常比在环境pH较低的低产盆地中预期的甲基汞（MeHg）浓度低。由于鱼类的甲基汞来源主要来自饮食，因此食物网的组成部分有望成为甲基汞向鱼类转移的关键控制。在这里，我们调查了Leptodora kindtii是大型（1.5厘米）的半透明掠食性无脊椎动物，具有明显的diel垂直迁移（白天在沉积物中，夜晚在上层水柱中），在研究充分，富营养化的大草原中，对甲基汞对鱼的污染具有调节作用在加拿大西部的湖泊。对无脊椎动物生物量和MeHg的diel通量的估计表明，成年迁徙的Leptodora，而不是其他成年浮游动物或幼年的Leptodora充当媒介，将甲基汞从假定的深水甲基化位点独特地转移到中上层鱼类群落中。这种神秘的过程表明，即使在生物地球化学特征，MeHg来源和白天的食物网配置表明营养传递应该最小的情况下，食鱼鱼可能会大大暴露于MeHg。

更新日期：2020-08-11

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