We conducted a national-scale assessment of mercury (Hg) bioaccumulation in aquatic ecosystems, using dragonfly larvae as biosentinels, by developing a citizen-science network to facilitate biological sampling. Implementing a carefully designed sampling methodology for citizen scientists, we developed an effective framework for a landscape-level inquiry that might otherwise be resource limited. We assessed the variation in dragonfly Hg concentrations across >450 sites spanning 100 United States National Park Service units and examined intrinsic and extrinsic factors associated with the variation in Hg concentrations. Mercury concentrations ranged between 10.4 and 1411 ng/g dry weight across sites and varied among habitat types. Dragonfly total Hg (THg) concentrations were up to 1.8-fold higher in lotic habitats than in lentic habitats and 37% higher in waterbodies with abundant wetlands along their margins than those without wetlands. Mercury concentrations in dragonflies differed among families but were correlated (r² > 0.80) with each other, enabling adjustment to a consistent family to facilitate spatial comparisons among sampling units. Dragonfly THg concentrations were positively correlated with THg concentrations in both fish and amphibians from the same locations, indicating that dragonfly larvae are effective indicators of Hg bioavailability in aquatic food webs. We used these relationships to develop an integrated impairment index of Hg risk to aquatic ecosytems and found that 12% of site-years exceeded high or severe benchmarks of fish, wildlife, or human health risk. Collectively, this continental-scale study demonstrates the utility of dragonfly larvae for estimating the potential mercury risk to fish and wildlife in aquatic ecosystems and provides a framework for engaging citizen science as a component of landscape Hg monitoring programs.

中文翻译：

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使用蜻蜓幼虫作为生物前哨通过公民科学框架对美国国家公园中汞的生物累积进行国家级评估。

我们通过建立一个公民科学网络以促进生物采样，以蜻蜓幼虫为生物前哨，对水生生态系统中汞（Hg）生物积累进行了国家级评估。通过为公民科学家实施精心设计的抽样方法，我们为景观层面的调查开发了有效的框架，否则可能会受到资源的限制。我们评估了跨越跨越100个美国国家公园管理局单位的超过450个站点的蜻蜓中Hg浓度的变化，并研究了与Hg浓度变化相关的内在和外在因素。各地点的汞浓度范围为10.4至1411 ng / g干重，并且随生境类型的不同而变化。蜻蜓的总Hg（THg）浓度高达1。与边缘地带的湿地相比，有很多湿地的水体中，抽水地的栖息地比透镜状地高8倍，水体高37％。蜻蜓中的汞浓度在家庭之间有所不同，但相关（r²> 0.80），从而可以调整为一个一致的族，以促进采样单位之间的空间比较。在同一地点，鱼类和两栖动物中的蜻蜓THg浓度与THg浓度呈正相关，这表明蜻蜓幼虫是水生食物网中Hg生物利用度的有效指标。我们利用这些关系建立了水生生态系统汞风险的综合损害指数，发现12％的站点年超过了鱼类，野生动植物或人类健康风险的高或严重基准。总的来说，这项大陆规模的研究证明了蜻蜓幼虫在估算水生生态系统中鱼类和野生动植物的潜在汞风险中的实用性，并为将公民科学纳入景观汞监测计划提供了框架。