title: Burrowing dragonfly larvae as biosentinels of methylmercury in freshwater food webs.
abstract: We assessed the utility of larval burrowing dragonflies (Odonata: Anisoptera: Gomphidae) as biosentinels of methylmercury (MeHg) contamination. Gomphids were the most abundant family of dragonflies sampled during 2008-2010 from 17 lakes in four national parks of the northwestern Laurentian Great Lakes region. Ten species of burrowing gomphids were sampled; 13 lakes contained 3 or more species, and 2 species of Gomphus co-occurred in 12 lakes. Most of the total Hg (THg) in whole, late-instar larvae was MeHg, with mean percent MeHg exceeding 60% in 16 lakes. Mean MeHg in larvae of a given species varied greatly among lakes, ranging from 4 to 109 ng g(-1) dry weight. Methylmercury levels in larvae, however, were much less variable within a given lake and species. The mean concentration of MeHg in burrowing gomphids was positively correlated with mean MeHg concentration in unfiltered lake water. Mean concentrations of THg and MeHg in multispecies assemblages of Gomphus were also positively correlated with mean THg in coexisting prey fish and game fishes. We recommend-and provide guidance on-the application of burrowing gomphids as biosentinels of MeHg contamination, which can extend the bioassessment of MeHg to fishless fresh waters.
authors.affiliation: River Studies Center, University of Wisconsin-La Crosse , La Crosse, Wisconsin 54601, United States. rharo@uwlax.edu
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Haro
authors.forename: Sean W
authors.initials: SW
authors.lastname: Bailey
authors.forename: Reid M
authors.initials: RM
authors.lastname: Northwick
authors.forename: Kristofer R
authors.initials: KR
authors.lastname: Rolfhus
authors.forename: Mark B
authors.initials: MB
authors.lastname: Sandheinrich
authors.forename: James G
authors.initials: JG
authors.lastname: Wiener
mesh_terms: D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D005399:Fishes; D020387:Food Chain; D005618:Fresh Water / Q000737:chemistry*; D007814:Larva / Q000187:drug effects*; D008767:Methylmercury Compounds / Q000032:analysis* / Q000633:toxicity; D063191:Odonata / Q000187:drug effects* / Q000254:growth & development; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical