Effects of methyl mercury exposure on the growth of juvenile common loons.
We conducted a dose-response laboratory study to quantify the level of mercury exposure associated with negative effects on the development of common loon chicks reared in captivity from hatch to 105 days. A dose regimen was implemented that provided exposure levels that bracketed relevant exposure levels of methyl mercury found in loon chicks across North America. We observed no overt signs of mercury toxicosis and detected no significant effect of dietary mercury exposure on growth or food consumption. However, asymptotic mass was lower in chicks that hatched from eggs collected from nests on low pH lakes relative to eggs from neutral pH lakes. Rapid excretion of methyl mercury during feather growth likely provides loon chicks protection from methyl mercury toxicity and may explain the lack of convincing toxicological findings in this study. Lake-source effects suggest that in ovo exposure to methyl mercury or other factors related to lake pH have consequences on chick development.
Kenow
Kevin P
KP
US Geological Survey, Upper Midwest Environmental Sciences Center, 2630 Fanta Reed Road, La Crosse, WI 54603, USA. kevin_kenow@usgs.gov
Gutreuter
Steve
S
Hines
Randy K
RK
Meyer
Michael W
MW
Fournier
Francois
F
Karasov
William H
WH
D000284:Administration, Oral; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development; D001717:Birds / Q000254:growth & development*; D001835:Body Weight; D004305:Dose-Response Relationship, Drug; D005241:Feathers / Q000737:chemistry; D005247:Feeding Behavior; D006863:Hydrogen-Ion Concentration; D008767:Methylmercury Compounds / Q000009:adverse effects* / Q000493:pharmacokinetics; D010063:Ovum / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000009:adverse effects* / Q000493:pharmacokinetics
D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical