PT13 Aquatic Ecotoxicology I
Exhibit Hall
8:00 AM - Tuesday
(PT191) Response of northern leopard frog (Rana pipiens) embryos and tadpoles to chronic arsenic exposure.
Karasov, W1, 2, Gross, J2, Chen, T-H1, 1 Department of Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, USA2 Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, WI, USA
ABSTRACT- Three clutches of embryos were collected from a relatively uncontaminated site in the Fox River/Green Bay ecosystem. Larvae were exposed to environmentally relevant doses of arsenic (HNa2AsO4 ) at 20, 100, and 500 ug/L in Petri dishes for the first ten days and then in 4-gallon tanks until metamorphosis. Embryo survival (Gosner stage 17 to 25) was high across all treatment groups (97-99%). Embryonic malformations were recorded in 100 and 500 ug/L As treatments but approximated reported background levels (i.e., 2%). Tadpole growth (snout vent length) was suppressed in all treatments when compared to control (P < 0.01). Larvae exposed chronically to 20 ug/L As suffered significantly higher mortality from all other treatments including control (P < 0.05). Maximum tadpole swimming speed was reduced in all treatments compared to control (P < 0.05). Twenty and 100 ug/L As treatments exhibited significant decreases in time to metamorphosis and in number of larvae reaching metamorphosis from control and 500 ug/L As treatments (P < 0.05). Additionally metamorph malformation and mortality were significantly higher in 20 ug/L As treatment than in control (P < 0.05). This is the first study to evaluate the effects of environmental As concentrations (< 1000 ug/L As) in northern leopard frog larvae (embryo to metamorphic climax). Twenty and 100 ug/L As exposures produced significant effects on leopard frog tadpoles at doses below the United States Environmental Protection Agency′s freshwater quality chronic criterion (150 ug/L), indicating that this species may not be protected by this standard. Furthermore, the U-shaped dose-response curves observed in tadpole mortality and metamorphosis may add to the complexity of the risk assessment process. [Supported by Sea Grant R/MW-84]
Key words: arsenic, Rana pipiens, embryos, tadpoles