PARENT SESSION

PH08 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Thursday

(PH086) The influence of Ca on the bioavailability of Cd to crayfish.

Keteles, K¹, Smith, E¹, Johnson, D², Walter, T¹, ¹ University of Central Arkansas, Conway, AR, USA² Louisiana State University, Baton Rouge, LA, USA

ABSTRACT- Crayfish, Orconectes negectus, were obtained from two different streams (Rush Creek and Clabber Creek, Rush AR) in a historic lead-zinc mining impacted region and analyzed for trace metal body burdens. Although Rush Creek and Clabber Creek had similar aqueous Cd concentrations (56 and 46 g l^-1respectively), crayfish obtained from Rush Creek had significantly higher Cd body burdens (3.16±0.18 g g ^-1) than crayfish obtained from Clabber Creek (1.47 ±0.28 g g^-1 Cd) even when body burdens were standardized for the ambient Cd concentrations. CaCO₃ concentrations varied between the two streams (178±8 and 230 ±9 mg l^-1, respectively) and this variability could account for the difference in Cd biovailability between the two streams because of the chemical similarity of these elements. Therefore, a laboratory experiment was conducted to determine if Ca could displace Cd uptake in crayfish and if Cd is sequestered in the exoskeleton during Ca limitation. Crayfish, Procambrus sp. were exposed in individual jars containing Cd-spiked (nominal concentration of 50 g l^-1) artificial pond water (APW) with or without amended Ca (20 mg l ^-1), and control crayfish were placed in jars containing APW without amended Cd. Following 14 days of exposure, exoskeletons were excised from soft tissues and Cd concentrations were measured in both fractions. Results indicate that Ca limitation significantly enhances the uptake of Cd by Procambrus sp. Although there was not a significant difference between soft tissue and exoskeleton Cd levels, exoskeleton Cd burdens tended to be higher during Ca limitation. These results suggest that Ca ions may inhibit the uptake of Cd ions by a freshwater crustacean and this interaction is an important parameter to consider when predicting Cd bioavailability to freshwater crustaceans.

Key words: cadmium, bioavailability, crustacean