PM11 Wildlife Ecotoxicology
Exhibit Hall
8:00 AM - Monday
(PM205A) Effects of mercury exposure on the health and fitness of captive-reared common loon (Gavia immer) chicks.
Kenow, K, Hines, R, Meyer, M, Karasov, W, Fournier, F, Hoffman, D, Grasman, K, Spalding, M, Gendron-Fitzpatrick, A, Gutreuter, S, Spalding, S6, 6 College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
ABSTRACT- Quantification of the impact of contaminant exposure on wild populations is complicated by the confounding effects of environmental stressors. We conducted a dose-response laboratory study, where the confounding stressors were controlled, to quantify the level of mercury exposure associated with negative effects on survival and fitness of captive-reared common loon chicks. A dose regimen was implemented that provided exposure levels that bracketed the relevant environmental exposure levels of methyl mercury (MeHg) found in loon chicks across North America. Response variables that we assessed included measures of growth, behavior, foraging efficiency, biochemical and histologic changes, and immune function. We observed no overt signs of mercury toxicosis and found no significant difference in general behavior with exposure level. Results of a phyto-hemagglutinin skin response test, to evaluate lymphocyte-mediated immunity, suggest that loon chick immune systems are compromised at an ecologically relevant dietary exposure level (0.5 ig MeHgCl/g wet food intake). Physiologic and histologic analyses have not yet been finalized. We detected differences in several variables with respect to source of eggs (from nests on low pH/higher MeHg vs. neutral pH/lower MeHg lakes). Relative to chicks from neutral-pH lakes, chicks from low-pH lakes exhibited 1) higher blood Hg levels at hatch, 2) 3.8% lower hatch mass, 3) 7% lower asymptotic mass, 4) more time on brooding platforms, and 5) lower level of response to taped parental calls. Rapid MeHg excretion during feather growth likely provides loon chicks some level of protection from MeHg toxicity. Lake-source effects suggest that in ovo exposure to MeHg or other factors related to lake pH may have consequences on chick development and fitness.
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