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PM02 Metals in the Environment: Aquatic Biological Perspectives
(PM049) Variation in the toxicity of cadmium between four crayfish species in two genera.
Wigginton, A1, Brammell, B1, Shaw, J2, Birge, W1, Shaw, J2, 1 University of Kentucky, Lexington, Kentucky, USA2 Dartmouth College, Hanover, New Hampshire, USA
ABSTRACT- Crayfish species are potentially useful organisms for studying the effects of heavy metal pollution on invertebrates. They are omnivorous and thus are open to toxicant exposure from a variety of sources including the water column, adsorbed onto food stuff, or bioaccumulated in prey. Crayfish can serve as excellent model species to increase the knowledge-base for invertebrate ecotoxicology. To that end, a series of acute toxicity tests have been conducted on four species of crayfish in two genera, Orconectes juvenilis, O. placidus, Procambarus clarkii, and P. acutus. In tests with juveniles of both Orconectes species, the 96 hour LC50 was 1.6 times greater in O. juvenilis than O. placidus (0.060 mg Cd/L versus 0.037 mg Cd/L, respectively). The 96 hour LC10 values were 0.014 mg Cd/L and 0.003 mg Cd/L for O. juvenilis and O. placidus, respectively. Tests were performed on adults of all four species mentioned previously. For O. juvenilis toxicity values were LC10: 0.623 mg Cd/L; LC50: 2.442 mg Cd/L (96 h) and for O. placidus were LC10: 0.092 mg Cd/L; LC50: 0.487 mg Cd/L (96 h). For P. clarkii toxicity values were LC10: 0.622 mg Cd/L; LC50: 3.186 mg Cd/L (96 h) and for P. acutus were LC10: 0.074 mg Cd/L; LC50: 0.499 mg Cd/L (96 h). Both juvenile toxicity tests seemed to show a relationship between molting and mortality in exposed animals. In the juvenile O. juvenilis test, 15 of 112 total mortalities (13.4%) were associated with molting, while in the juvenile O. placidus test, 11 of 82 total mortalities (13.4%) occurred with molting. In the adult O. placidus test, 11 of 52 total mortalities (21.2%) happened in conjunction with molting. Regarding the adult P. acutus test, 20 of 67 total mortalities (29.9%) were associated with molting either during or within a week before the test. This indicates that molting may be a time of increased vulnerability to cadmium toxicity.
Key words: cadmium, crayfish, toxicity, molting
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