PT12 Metals and Bioaccumulation
Exhibit Hall
8:00 AM - Tuesday
(PT155) Bioaccumulation of dietary methylmercury in adults and eggs of fathead minnows.
Sandheinrich, M1, Hammerschmidt, C2, 1 University of Wisconsin-La Crosse, La Crosse, WI, USA2 University of Connecticut, Groton, CT, USA
ABSTRACT- Maternal transfer is the principal source of methylmercury (MeHg) to embryos of oviparous fishes. We examined accumulation of dietary MeHg in adults and eggs of female fathead minnows. Juvenile fish were fed one of four diets until sexual maturity (phase 1): a control diet (0.06 
g Hg g-1 dry weight) and three diets contaminated with MeHg at 0.88 (low), 4.11 (medium), and 8.46 g g-1 dry weight (high). At sexual maturity, male and female fish were paired, again fed one of the four diets, and allowed to reproduce (phase 2). To assess the significance of diet during gametogenesis on concentrations of MeHg in eggs, some females were fed diets during phase 2 that differed from those during phase 1. MeHg in eggs averaged about 30% of the adult concentration. Dietary concentration and number of days of dietary exposure accounted for 98% of the variability in MeHg in adults and eggs. MeHg increased rapidly in eggs from females fed a control during phase 1 and a contaminated diet during phase 2; after 10 d, eggs from fish fed the low MeHg diet were five times the concentration of those fed a control diet. These results indicate that female diet during oogenesis is a substantial source of MeHg to fish eggs. Accordingly, the potential coincidence of oogenesis with seasonally enhanced levels of MeHg may increase the predisposition of developing fish embryos to detrimental effects of maternally transferred MeHg.
Key words: fathead minnow, methylmercury, diet, oogenesis