Effects of Atrazine and Nitrate on Northern Leopard Frog (Rana Pipiens) Larvae Exposed in the Laboratory From Posthatch Through Metamorphosis

Abstract

Abstract-A recent ecological risk assessment of the herbicide atrazine found that the ecosystems at greatest risk within North America are the streams, rivers, and reservoirs of the midwestern corn-growing regions. Habitats adjacent to application areas could be exposed to high levels of atrazine during periods of amphibian activity such as breeding and migration. Because fertilizer application coincides both spatially and temporally with atrazine application in agricultural areas, we tested the effects of atrazine and nitrate on northern leopard frog (Rana pipiens) larvae in the laboratory. Larvae were exposed to atrazine (0, 20, and 200 g/ L) and nitrate (0, 5, and 30 mg NO 3 -N/L) from first-feeding stage through metamorphosis in a factorial design. Atrazine concentrations in metamorphosed juveniles were approximately six times the concentration in the water, indicating bioconcentration of atrazine by larvae. Atrazine, nitrate, and their interaction had no significant effect on development rate, percent metamorphosis, time to metamorphosis, percent survival, mass at metamorphosis, or hematocrit. However, nitrate slowed growth of larvae. Though this growth inhibition is statistically significant, it is probably not biologically important when compared with natural variation in the environment. Thus, concentrations of atrazine and nitrate commonly found in the environment do not appear to pose a significant threat to R. pipiens larvae through direct toxicity.

Atrazine-induced hermaphroditism at 0.1 ppb in American leopard frogs (Rana pipiens): laboratory and field evidence.

“…In a previous study, Allran and Karasov (2000) examined the effects of atrazine on R. pipiens, but they used much higher doses and did not examine gonadal differentiation. Thus, their study did not identify the abnormalities that we observed here.…”

Cyanosis by methemoglobinemia in tadpoles of Cochranella granulosa (Anura: Centrolenidae)

“…Some authors report no damage to tadpoles reared in water high in nitrate content (Langan 2003, Allran & Karasov 2000. Hecnar (1995), however, found considerable differences between the tadpoles of Pseudacris triseriata and Rana pipiens with lower survival rates in both compared to the more resistant Rana clamitans tadpoles.…”

Nitrogen Control of Atrazine Utilization in Pseudomonas sp. StrainADP

“…Its widespread use and high mobility in soil have led to its frequent detection in surface water and groundwater at concentrations exceeding the maximum levels allowed (21,22,30,37). The high incidence of atrazine-contaminated water and the increasing concern about the toxicological and ecotoxicological properties of atrazine (3,6,16,17) have boosted research directed toward bioremediation of atrazine-polluted sites.A few laboratories have reported the isolation of bacteria with the ability to utilize atrazine, achieving in some cases the complete mineralization of the herbicide (see reference 29 and references therein). The best-characterized atrazine-mineralizing bacterial strain is Pseudomonas sp.…”