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Effects of Injected Methylmercury on the Hatching of Common Loon (Gavia immer) Eggs
Citation:
KENOW, K. P., M. W. MEYER, R. ROSSMANN, A. GENDRON-FITZPATRICK, AND B. R. GRAY. Effects of Injected Methylmercury on the Hatching of Common Loon (Gavia immer) Eggs . Ecotoxicology. Springer Science+Business Media, 20(7):1684-1693, (2011).
Impact/Purpose:
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 (LC50) 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 (r2 = 0.80) with egg Hg concentration.
Description:
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 (LC50) 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 (r2 = 0.80) with egg Hg concentration.
