The Effects of Experimental Reservoir Creation on the Bioaccumulation of Methylmercury and Reproductive Success of Tree Swallows (Tachycineta bicolor)

Reservoir creation results in decomposition of flooded organic matter and increased rates of mercury methylation. Methylmercury (MeHg), the most toxic form of mercury, bioaccumulates through aquatic food webs. Our objective was to quantify the transfer of MeHg from aquatic food webs into terrestrial...

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Bibliographic Details
Published in:Environmental science & technology 2001-04, Vol.35 (7), p.1329-1338
Main Authors: Gerrard, Pauline M, St. Louis, Vincent L
Format: Article
Language:English
Subjects:
Animal reproduction
Animal, plant and microbial ecology
Animals
Applied ecology
Aves
Biological and medical sciences
Birds
Diet
Disasters
Ecotoxicology, biological effects of pollution
Effects of pollution and side effects of pesticides on vertebrates
Environmental impact
Food Chain
Fundamental and applied biological sciences. Psychology
General aspects
Mercury
Methylmercury Compounds - pharmacokinetics
Reservoirs
Songbirds - growth & development
Tachycineta bicolor
Tissue Distribution
Toxicity
Waste Disposal, Fluid
Water Pollutants, Chemical - pharmacokinetics
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Summary:Reservoir creation results in decomposition of flooded organic matter and increased rates of mercury methylation. Methylmercury (MeHg), the most toxic form of mercury, bioaccumulates through aquatic food webs. Our objective was to quantify the transfer of MeHg from aquatic food webs into terrestrial organisms. We examined rates of MeHg bioaccumulation in an insectivorous songbird, the tree swallow, breeding near an experimentally created reservoir. We also determined the impact of flooding and MeHg bioaccumulation on the reproductive success of these birds. Mean MeHg burdens in nestling swallows from near the experimental reservoir increased from 1210 ± 150 ng before flooding to 2200 ± 102 ng after flooding. Postflood MeHg concentrations in both the body and feathers of the birds were significantly greater than preflood MeHg concentra tions. Although MeHg burdens in swallows were elevated in postflood years, we found no overt toxicological affects. An increase in dipteran productivity (the primary food source of tree swallows) after reservoir creation resulted in earlier nest initiation, larger eggs, and faster growth rates of wing and bill length in nestlings raised during postflood years.
ISSN:0013-936X
1520-5851
DOI:10.1021/es001537f