Tolerance of the sheepshead minnow, (Cyprinodon variegatus), to selected environmental and chemical challenges
- Environmental Protection Agency, Gulf Breeze, FL (United States)
- Univ. of North Texas, Denton, TX (United States)
The sheepshead minnow is the most widely used vertebrate for estuarine toxicity testing, yet little is known about its autecology or toxicant susceptibility relative to other fishes. Sheepshead minnows are more tolerant of temperature, salinity and hypoxic extremes than are any known teleost species. The ecological and physiological thermo-tolerance polygons for sheepshead minnow (1,380 C and 1,470 C) are the largest ever measured for a fish. Sheepshead minnows are osmoregulators at ambient salinities between 0 and 70% and can survive salinity > 180{per_thousand} for extended periods. In addition, sheepshead minnows exposed to progressive hypoxia have an oxygen tolerance of 0.22 mg/l (EC50, equilibrium). This exceptional tolerance of abiotic challenges is also apparent in the sheepshead minnow`s atypical response to toxicant exposure. The US EPA aquatic toxicity database AQUIRE lists 153 different toxicants for which sheepshead minnows have been tested since about 1970. For more than 50% of these toxicants, sheepshead minnows are the only species tested. Interspecific toxicity comparisons of the remaining toxicants are limited to 28 due to dissimilar test parameters. For 63% of these toxicants, sheepshead minnows proved to be the most tolerant (i.e., greatest LC50 value). In contrast, these fish are most sensitive to only 20% of the toxicants and are never the most sensitive in instances where at least two other species were tested. In addition to demonstrating the fish`s tolerance of natural and anthropogenic abiotic challenges, these data emphasize the need for a greater understanding of the physiological and toxicological relationships among sheepshead minnows and other fishes if meaningful interpretations are to be made.
- OSTI ID:
- 367550
- Report Number(s):
- CONF-9511137-; ISBN 1-880611-03-1; TRN: IM9640%%296
- Resource Relation:
- Conference: 2. Society of Environmental Toxicology and Chemistry (SETAC) world conference, Vancouver (Canada), 5-9 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Second SETAC world congress (16. annual meeting): Abstract book. Global environmental protection: Science, politics, and common sense; PB: 378 p.
- Country of Publication:
- United States
- Language:
- English
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