PARENT SESSION
PS6 - Contaminant Effects on Amphibians & Reptiles
Sunday, 17 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P088) Development of a Standardized Short-Term Sediment Toxicity Test using Amphibians.
Pillard, David*,1, Bleiler, John2, Speicher, Jason3, Barclift, David3, DuFresne, Doree1, Fowler, Amy4, 1 ENSR International, Ft. Collins, CO, USA2 ENSR International, Westford, MA, USA3 U.S. Navy EFANE, Lester, PA, USA4 U.S. Navy NFESC, Port Hueneme, CA, USA
ABSTRACT- Amphibians are often considered a front-line indicator of possible adverse impacts to wetland ecosystems and considerable research has been dedicated to examining reported teratogenicity and overall declining populations. Even though sediments can act as a major repository for certain contaminants, no standardized procedure exists to evaluate the potential toxicity of sediments to amphibians. This study examined the critical factors for developing a sediment test for amphibians. Tests were conducted to evaluate appropriate test parameters, including test chambers, food, exposure design, control sediment, ammonia tolerances, length of test, age at test initiation, and most sensitive sublethal endpoints. Organisms tested were Northern Leopard Frog (Rana pipiens) and American Toad (Bufo americanus). It was found that tadpoles grew best when fed either TetraMin or a mix of TetraMin and Trout Chow. Tests of 14 and 21 days did not necessarily indicate greater effects than did tests of only 7 days in duration, when organisms were exposed to copper, cadmium, or various salts. Various sublethal endpoints were examined including total and body length, body width, metamorphic (Gosner) stage, and weight. Although several endpoints indicated sublethal effects (lower NOECs), body length and width were more consistent sublethal effect indicators, even more so than metamorphic stage. These studies also showed that the sensitivity of Rana pipiens and Bufo americanus tadpoles decreases as they age. As with other sediment and even water-column tests, a short-term amphibian study will not necessarily address long-term and/or multi-generational effects of very low-levels of contaminants. However, amphibians can be used as another indicator of possible adverse effects of sediment-bound chemicals.
Key words: amphibians, sediment, wetlands, chronic toxicity