Meeting Abstract
P3.14 Tuesday, Jan. 6 Effect of cadmium exposure on critical temperatures and energy metabolism of the eastern oysters Crassostrea virginica BAGWE, R; SOKOLOVA, IM*; University of North Carolina, Charlotte; University of North Craolina,Charlote isokolov@uncc.edu
Marine intertidal molluscs are exposed to multiple stressors (including temperature and pollution) in estuaries, which can strongly affect their physiology. According to the concept of critical temperatures (Poertner, 2002), temperature tolerance in aquatic ectotherms is limited by the reduction of aerobic scope at sub- and supra-optimal temperatures until it completely disappears at the critical temperatures (Tc) and transition to partial anaerobiosis occurs. We determined the onset of anaerobic metabolism and changes in cellular energy budget in eastern oysters Crassostrea virginica during acute temperature rise (20C-36C) in order to determine the Tc and reveal whether exposure to cadmium ( 50 ug L-1 for 30 days) affects Tc. Our data show that as temperature increases, oysters switch to an anaerobic mode of metabolism as indicated by accumulation of anaerobic end products and insufficiency of cellular energy. In control oysters, L-alanine, acetate and succinate significantly rose above the control levels and ATP concentrations declined at 24C indicating that this is close to Tc for this population. At higher temperatures, anaerobic end products continued to accumulate but ATP levels returned to the control indicating that oysters were capable of at least short-term regulation of cellular energy balance in the studied temperature range. Cd-exposed oysters demonstrated significantly lower accumulation of anaerobic end products compared to their control counterparts at all temperatures. Given that elevated temperatures lead to hypoxemia in Cd-exposed oysters (Lannig et al., 2008), these data suggest that cadmium exposure inhibits anaerobic pathways in oysters and indicates that accumulation of anaerobic end products is not a good index of Tc in Cd-exposed oysters.
