title: Effects of injected methylmercury on the hatching of common loon (Gavia immer) eggs.
abstract: To determine the level of in ovo methylmercury (MeHg) exposure that results in detrimental effects on fitness and survival of loon embryos and hatched chicks, we conducted a field study in which we injected eggs with various doses of MeHg on day 4 of incubation. Eggs were collected following about 23 days of natural incubation and artificially incubated to observe hatching. Reduced embryo survival was evident in eggs injected at a rate of ≥1.3 μg Hg/g wet-mass. When maternally deposited Hg and injected Hg were considered together, the median lethal concentration of Hg (LC(50)) was estimated to be 1.78 μg Hg/g wet-mass. Organ mass patterns from eggs of chicks injected at a rate of 2.9 μg Hg/g differed from that of controls and chicks from the 0.5 μg Hg/g treatment, largely related to a negative relation between yolk sac mass and egg mercury concentration. Chicks from eggs in the 2.9 μg Hg/g treatment were also less responsive to a frightening stimulus than controls and chicks from the 0.5 μg Hg/g treatment. We also found that the length of incubation period increased with increasing egg mercury concentration. Tissue Hg concentrations were strongly associated (r(2) ≥ 0.80) with egg Hg concentration.
authors.affiliation: Upper Midwest Environmental Sciences Center, US Geological Survey, La Crosse, WI 54603, USA. kkenow@usgs.gov
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Kenow
authors.forename: Michael W
authors.initials: MW
authors.lastname: Meyer
authors.forename: Ronald
authors.initials: R
authors.lastname: Rossmann
authors.forename: Annette
authors.initials: A
authors.lastname: Gendron-Fitzpatrick
authors.forename: Brian R
authors.initials: BR
authors.lastname: Gray
mesh_terms: D000818:Animals; D001717:Birds; D004781:Environmental Exposure / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D006863:Hydrogen-Ion Concentration; D060106:Lakes / Q000737:chemistry; D008628:Mercury / Q000493:pharmacokinetics / Q000633:toxicity*; D008767:Methylmercury Compounds / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D010063:Ovum / Q000187:drug effects*; D012307:Risk Factors; D013045:Species Specificity; D014018:Tissue Distribution; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics / Q000633:toxicity
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury