PW01 Wildlife Toxicology
Exhibit Hall
8:00 AM - Wednesday, 12 November 2003
(PW035) Maternal transfer of mercury in fish and reptiles: concentrations in eggs versus somatic tissues.
Jagoe, C1, Brant, H1, Wall, A1, Glenn, T1, 2, Strickland, D2, Hauswaldt, S2, Sepulveda, M3, Arnold, B3, Gross, T3, 1 Savannah River Ecology Laboratory, Aiken, SC, USA2 University of South Carolina, Columbia, SC, USA3 USGS-BRD, Gainsville, Fl
ABSTRACT- Lower vertebrates exposed to environmental methylmercury can accumulate relatively high concentrations of this substance in their tissues. During oogenesis, some of this burden may be transferred into eggs. Such transfer may represent a potential mercury excretion route for the female, and a potential source of mercury to the developing embryo. To evaluate whether maternal transfer was of sufficient magnitude to represent either a significant sink for maternal mercury or a significant source of mercury to offspring, we measured mercury in tissues and eggs of a reptile, American alligator (Alligator mississippiensis) and a teleost, largemouth bass (Micopterus salmoides) collected at locations in Florida and South Carolina, USA. Both are large carnivores, and as top level predators, often contain over 1 mg / kg Hg in muscle. In alligators, mean mercury concentrations in yolk and albumin of undeveloped eggs were less than 0.15 mg / kg dry weight. We calculated an average total burden of about 8 ug Hg per egg. Based on average clutch size, the amount of Hg excreted by a typical female alligator via eggs each year would only be 0.1 % of the total body burden. For bass, egg mercury averaged less than 0.1 mg / kg wet weight, and egg mass accounted for about 2% of maternal body weight. Based on these values, the amount of Hg excreted by a female bass in eggs per year would be about 0.4 % of the total body burden. It appears that eggs represent only a small potential sink for accumulated Hg in these animals.
Key words: fish, reptile, mercury , egg