title: Bioenergetic and pharmacokinetic model for exposure of common loon (Gavia immer) chicks to methylmercury.
abstract: A bioenergetics model was used to predict food intake of common loon (Gavia immer) chicks as a function of body mass during development, and a pharmacokinetics model, based on first-order kinetics in a single compartment, was used to predict blood Hg level as a function of food intake rate, food Hg content, body mass, and Hg absorption and elimination. Predictions were tested in captive growing chicks fed trout (Salmo gairdneri) with average MeHg concentrations of 0.02 (control), 0.4, and 1.2 microg/g wet mass (delivered as CH3HgCl). Predicted food intake matched observed intake through 50 d of age but then exceeded observed intake by an amount that grew progressively larger with age, reaching a significant overestimate of 28% by the end of the trial. Respiration in older, nongrowing birds probably was overestimated by using rates measured in younger, growing birds. Close agreement was found between simulations and measured blood Hg, which varied significantly with dietary Hg and age. Although chicks may hatch with different blood Hg levels, their blood level is determined mainly by dietary Hg level beyond approximately two weeks of age. The model also may be useful for predicting Hg levels in adults and in the eggs that they lay, but its accuracy in both chicks and adults needs to be tested in free-living birds.
authors: Department of Wildlife Ecology, 226 Russell Labs, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. wkarasov@wisc.edu
authors: William H
authors: WH
authors: Karasov
authors: Kevin P
authors: KP
authors: Kenow
authors: Michael W
authors: MW
authors: Meyer
authors: Francois
authors: F
authors: Fournier
mesh_terms: D000367:Age Factors; D000818:Animals; D001717:Birds / Q000378:metabolism*; D001835:Body Weight; D004435:Eating; D004734:Energy Metabolism; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D005504:Food Analysis; D008767:Methylmercury Compounds / Q000097:blood / Q000493:pharmacokinetics* / Q000633:toxicity; D008954:Models, Biological; D014922:Wisconsin
chemical_list: D008767:Methylmercury Compounds