Seasonality of dipteran‐mediated methylmercury flux from ponds. (11th April 2018)

• Record Type: Journal Article
• Authors: Chumchal, Matthew M.; Drenner, Ray W.; Hall, MacGregor N.; Polk, D. Kirkland; Williams, Edward B.; Ortega‐Rodriguez, Celeste L.; Kennedy, James H.
• Is Part Of: Environmental toxicology and chemistry. Volume 37:Number 7(2018)
• Page Start: 1846
• Page End: 1851
• Publication Date: 2018-04-11
• Subjects: Insect‐mediated methylmercury flux -- Seasonality -- Pond permanence; Pollution -- Environmental aspects -- Periodicals; Environmental chemistry -- Periodicals; 615.902
• DOI: 10.1002/etc.4134
• Languages: English
• ISSNs: 0730-7268

Abstract

Abstract: Methylmercury (MeHg) is an aquatic contaminant that can be transferred to terrestrial predators by emergent aquatic insects. We assessed the effects of month and pond permanence on dipteran‐mediated MeHg flux (calculated as emergent dipteran biomass × dipteran MeHg concentration) in 10 experimental ponds. Emergent dipterans were collected weekly from permanent ponds with bluegill ( Lepomis macrochirus ; n = 5) and semipermanent ponds without fish ( n = 5) over a 7‐mo period (February–August, 2015). We detected a significant effect of month on MeHg flux from 6 dipteran taxa and aggregate MeHg flux, with the highest MeHg flux from herbivorous/detritivorous chironomid midges and predatory midges in March; biting midges, phantom midges and herbivorous/detritivorous orthoclad midges in April; and mosquitoes in August. Aggregate dipteran‐mediated MeHg flux peaked in April and then declined throughout the remainder of the summer. We did not detect a significant main effect of pond permanence or a significant month × pond permanence interaction effect on MeHg flux for any of the taxa examined in the present study or for aggregate MeHg flux. Given their ubiquity in aquatic systems and their importance in food webs at the land–water interface, dipterans are important taxa that should not be overlooked as a part of the Hg cycle. Environ Toxicol Chem 2018;37:1846–1851. © 2018 SETAC Abstract : Methylmercury (MeHg) is an aquatic contaminant that can be transferred to terrestrial predators by emergent aquatic insects, such as midges (i.e., dipterans). In the present study, dipteran‐mediated MeHg flux was strongly regulated by season but not pond permanence and the presence of fish.