Meeting Abstract

P2.33  Saturday, Jan. 5  Elevated CO₂ levels affect cellular uptake and homeostasis of trace metals in hard shell clams Mercenaria mercenaria SOKOLOVA, I.*; IVANINA, A.; BENIASH, E.; University of North Carolina at Charlotte; University of North Carolina at Charlotte; University of Pittsburgh isokolov@uncc.edu

Estuarine bivalves are susceptible to environmental stressors such as ocean acidification and heavy metal pollution which can interactively affect their performance and survival. We studied the interactive effects of elevated PCO2 (hypercapnia) and metals (Cd and Cu) on acid-base and metal homeostasis in isolated mantle cells of a hard shell clam Mercenaria mercenaria. Isolated cells were exposed for 2 h to 0.04, 1.52 or 3.01 kPa PCO2 [representative of the ambient CO2 conditions and the hemolymph PCO2 at the ambient and elevated CO2 (400 and 800 ppm, respectively)] to five different metals concentrations: control (no added metals), 25 µM Cd, 100 µM Cd, 1 µM Cu or 5 µM Cu. Extracellular and intracellular pH decreased with increasing PCO2 but was not affected by the metal exposure. Exposure of the mantle cells to Cd resulted in a concentration-dependent increase in the level of total and free intracellular Cd2+. Notably, Cd uptake was significantly lower at elevated PCO2. Cd exposure also led to a dramatic increase in free intracellular [Zn2+], which was considerably higher at low PCO2 levels and strongly correlated with the total intracellular Cd burdens. In contrast, Cu exposure did not affect free intracellular [Zn2+] but led to a significant increase in the intracellular levels of free Cu2+ and Fe2+, which was strongly potentiated by elevated PCO2. Exposure to metals resulted in the elevated levels of reactive oxygen species during the ambient air exposure but not at elevated PCO2. These data suggests that environmental CO2 levels can strongly modulate uptake and toxicity of trace metals in clams and that toxic effects of Cu are likely to be increased at elevated PCO2, whereas cellular toxicity of Cd may be partially alleviated by hypercapnia. Supported by NSF IOS-0951079.