TP9 Ecotoxicology of Atrazine in Amphibians
Room 12A/B, Level 4
2:10 PM - 5:30 PM, Tuesday, 11 November 2003
Chair: Solomon, Keith ,
Co-chair: Smith, Ernest ,
(320) Atrazine induced hyperactivity increases susceptibility to predation and water loss in a salamander.
ROHR, J1, SIH, A2, KERBY, J2, ELSKUS, A1, SHEPHERD, B1, CROWLEY, P1, PALMER, B1, 1 UNIVERSITY OF KENTUCKY, LEXINGTON, KY, USA2 UNIVERSITY OF CALIFORNIA, DAVIS, CA, USA
ABSTRACT- We investigated the effects of the herbicide atrazine on the antipredator behaviors, predation rates, and osmoregulation of streamside salamanders (Ambystoma barbouri). Larvae were exposed to 0, 40, 400, and 800 
g/L of atrazine for four days in aquaria with translucent glass refuge plates. Within the first five h of exposure and for the remaining exposure duration, larvae experiencing 400 and 800 g/L of atrazine exhibited greater activity and lower refuge use than control larvae. When exposed to green sunfish (Lepomis cyanellus) on day 5, 400 and 800 g/L larvae continued to exhibit hyperactivity and reduced refuge use, and consequently experienced greater sunfish predation than control larvae. In nature, larvae in stream pools containing sunfish typically decrease activity and increase refuge use during the day, but tend to drift out of these pools at night when the highly visual sunfish are less effective predators. However, 4-d exposure to 400 and 800 g/L of atrazine induced greater daytime and overall (day+night) drift rates in response to sunfish, which would presumably increase predation rates by both increasing daytime conspicuousness and encounter rates with fish. Embryos and larvae were also exposed to 0, 4, 40, and 400 g/L of atrazine until metamorphosis to quantify the post-exposure effects of atrazine on terrestrial juveniles. Approximately 5 months after atrazine exposure had ceased, metamorphs previously exposed to 40 and 400 g/L remained hyperactive and did not readily exhibit water conserving postures when tested under dry conditions. As a result, their rate of water loss during the 5-h trial was significantly greater than that of control salamanders, indicating greater desiccation risk. Collectively, these results demonstrate that ecologically relevant concentrations and exposure durations of atrazine have the potential to increase amphibian predation rates, and that the adverse effects of atrazine can persist well after exposure has ceased. EPA STAR R829086.
Key words: osmoregulation, behavior, atrazine, metamorphs