Please join the Great Lakes Center for a seminar presented by Dr. Martin Stepanian, from the U.S. Geological Survey's Lake Erie Biological Station. The seminar will be held on Thursday, April 23rd from 12:15 to 1:30 p.m. in Classroom Building B118.
Male fish typically have higher metabolisms than adult females. Therefore, feeding rates, accumulation of contaminants, and excretion rates are expected to be higher in males. Ingested mercury (Hg) is eliminated from the bodies of fish whereas polychlorinated biphenyls (PCBs) are not. Low-chlorinated PCB congeners are dispersed farther from their sources owing to greater volatility.
Stepanian compared male and female burbot (Lota lota) captured from a contaminated lake (Lake Erie) and a pristine lake (Great Slave Lake: GSL) with respect to concentrations of mercury and PCBs, and congener distributions of PCBs. He predicted (1) higher concentrations of total PCBs in burbot from Lake Erie; (2) higher total PCBs in males than females in both lakes; (3) higher proportions of low-congener PCBs in GSL burbot; and (4) higher male: female PCB ratios than Hg ratios. All predictions were verified. However, old (age 14-17) male burbot from Lake Erie had higher proportions of hexachlorinated congeners than other demographics, suggesting that old males had fed at a PCB “hot spot.”
Further, the latitudinal effect on PCB congener distribution may be more complex than that portrayed in previous studies. Unlike other fishes studied, female burbot had higher concentrations of mercury than males. The unusually high gonadosomatic index of burbot suggests that this result was due to higher concentrations of androgens, which is associated with higher elimination rates in males.
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