MENDONCA, M.T.; TRUCKS, K.T.: Comparison of aromatase activity in female yellow-blotched map turtles from contaminant impacted vs. reference sites

Yellow-blotched map turtles, Graptemys flavimaculata, from a portion of the Pascagoula River drainage system in Mississippi, USA, impacted by paper mill efflent, exhibit low reproductive rates. Significantly fewer females from a historically contaminated site develop second clutches when compared to females from a reference site (e.g. 17% vs 50%). However, there were no significant differences found in the monthly mean plasma 17BETA-estrodiol (E) levels of females from the two sites. Female fish from sites contaminated by bleached kraft mill effluent exhibit lowered E as well as lowered ovarian aromatase activity. We compared aromatase activity in ovarian and hepatic tissue of females collected from an impacted and reference site in June-July, 1999. Female map turtles from the contaminated site exhibited significantly lower mean ovarian aromatase activity levels than those from the reference site. Hepatic aromatase activity did not differ between sites. In June-July 2000, we collected additional females from the two sites, and biopsied several ovarian follicles from them. The difference in aromatase activity between sites using the biopsied follicles did not differ from the pattern found when entire ovaries were used in 1999 when corrected for protein content. Additionally, we examined the levels of aromatase mRNA of embryos from impacted and reference sites and these results will be discussed. This research funded by Mississippi-Alabama Sea Grant R/ER-43PD.