Mercury Transfer From Aquatic Insects to Arctic Food Webs: Assessing Insect Mediated Methyl Mercury Flux and Mercury Contamination Risks
Sullivan, Emma
Sullivan, Emma
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2024-12-18
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Abstract
Mercury (Hg) is a global contaminant of significant ecological concern, particularly in aquatic systems. While inorganic mercury (IHg) is relatively nontoxic and does not bioaccumulate, microbial processes in aquatic environments convert IHg to methylmercury (MeHg), a highly toxic and bioavailable form that readily accumulates in organisms. Aquatic insects, which feed on primary producers such as algae during their larval stages, can accumulate substantial MeHg levels. Upon emerging as adults, these insects transport MeHg from aquatic ecosystems to adjacent terrestrial environments, facilitating cross-ecosystem mercury transfer.
This study quantified dipteran-mediated Hg flux in five ponds and one lake in the high Arctic (NW Greenland) during the summer of 2023. Emergent dipterans were collected weekly, and Hg flux was calculated based on biomass and mercury concentrations. Results revealed that Hg flux varied significantly by location and insect taxon, influenced by variation in both biomass and Hg concentrations. Risk analyses for Snow Bunting (Plectrophenax nivalis) and Lapland Longspur (Calcarius lapponicus) chicks consuming emergent aquatic insects indicated no direct risk from this dietary exposure. However, previous research highlights the significant role of emerging insects in Hg bioaccumulation within riparian spiders, raising concerns about secondary risks to arachnivorous birds.