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PT13 Aquatic Ecotoxicology I
(PT202) Effects of cadmium on metal body burden in four crayfish species in two genera.
Wigginton, A1, Schoepp, H2, Price, D1, Birge, W1, 1 University of Kentucky, Lexington, Kentucky, USA2 Northrop Grumman Corporation, Los Angeles, California, USA
ABSTRACT- Crayfish species are potentially useful model organisms for studying effects of heavy metal pollution on invertebrates. They are omnivorous and hence open to toxicant exposure from many sources including ambient water, adsorbed onto food items, or bioaccumulated in prey. Additionally, they are easily maintained in captivity and are a convenient size for physiological research. To increase the knowledge-base for invertebrate ecotoxicology, a series of acute toxicity tests were conducted on four species of crayfish in two genera, Orconectes juvenilis, O. placidus, Procambarus clarkii, and P. acutus. At the end of each test, tissues from individuals were subsampled for body burden analysis using ICP-OES and GFAAS. This combination of techniques allowed for the quantification of the impact of cadmium exposure on the concentration of 28 elements in crayfish tissues. Among the four crayfish species tested, 96h LC50 values varied between 0.487 mgCd/L and 3.186 mgCd/L, while 96h LC10 values varied between 0.074 mgCd/L and 0.623 mgCd/L. Based on ANOVA analysis using Design Perfect version 6, released by Stat-Ease Inc., cadmium exposure in O. placidus demonstrated a significant effect upon Ba, Ca, Cd, Cu, and P concentrations at a p < 0.05. Zn showed a significant effect at p < 0.10. For O. juvenalis, Ca, Cd, Mg, Ti, and Zn showed significant effects at p < 0.05 and P showed as significant effect at p < 0.10. Cadmium exposure to P. acutus demonstrated a significant effect upon Ca, Cd, K, Na, and Zn at a p < 0.05. P. clarkii showed similar trends. Body burden measurements for individual tissues showed trends towards Cd accumulation in most tissues, while the response of other elements in different tissues varied considerably. There were trends consistent between experiments showing a decrease in Cu and Zn in the hepatopancreas, usually coupled with an increase of those elements in gill and green gland tissues. This indicates a possible acute toxicant remediation mechanism whereby protein bound Zn and Cu from the hepatopancreas is released as Cd accumulates in those proteins. These results indicate a wide variety of effects of cadmium upon physiological processes in crayfish.
Key words: cadmium, crayfish, toxicity, body burden
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