title: Effects of fish on emergent insect-mediated flux of methyl mercury across a gradient of contamination.
abstract: We examined the effects of fish predation on emergent insect-mediated methyl mercury (MeHg) flux across a gradient of MeHg contamination in experimental ponds. Emergent insects were collected from ponds with (n = 5) and without fish (n = 5) over a six week period using floating emergence traps. We found that the potential for MeHg flux increased with Hg contamination levels of the ponds but that the realized MeHg flux of individual insect taxa was determined by fish presence. Fish acted as size-selective predators and reduced MeHg flux by suppressing emergence of large insect taxa (dragonflies and damselflies) but not small insect taxa (chironomids and microcaddisflies). MeHg flux by small insect taxa was correlated with concentrations of MeHg in terrestrial spiders along the shorelines of the study ponds, demonstrating for the first time the cross-system transport of MeHg by emergent insects to a terrestrial spider.
authors.affiliation: Department of Biology, Texas Christian University, Winton Scott Room 401, 2800 South University Drive, Fort Worth, Texas 76129, United States.
authors.forename: Beth N
authors.initials: BN
authors.lastname: Tweedy
authors.forename: Ray W
authors.initials: RW
authors.lastname: Drenner
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Chumchal
authors.forename: James H
authors.initials: JH
authors.lastname: Kennedy
mesh_terms: D000818:Animals; D002683:Chironomidae / Q000187:drug effects; D004784:Environmental Monitoring; D005399:Fishes / Q000378:metabolism*; D060434:Herbivory / Q000187:drug effects; D007313:Insecta / Q000187:drug effects*; D008767:Methylmercury Compounds / Q000633:toxicity*; D013112:Spiders / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D014876:Water Pollution / Q000032:analysis*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical