Abstract

Estuaries are characterized by high fluctuation of their environmental conditions. Environmental parameters measured show that the seawater properties of the Quempillen estuary (i.e. temperature, salinity,pCO(2), pH and omega CaCO3) were highly fluctuating and related with season and tide. We test the effects of increasing temperature andpCO(2)in the seawater on the physiological energetics of the bivalveOstrea chilensis. Juvenile oysters were exposed to an orthogonal combination of three temperatures (10, 15, and 20 degrees C) and twopCO(2)levels (similar to 400 and similar to 1000 mu atm) for a period of 60 days to evaluate the temporal effect (i.e. 10, 20, 30, 60 days) on the physiological rates of the oysters. Results indicated a significant effect of temperature and time of exposure on the clearance rate, whilepCO(2)and the interaction betweenpCO(2)and the other factors studied did not show significant effects. Significant effects of temperature and time of exposure were also observed on the absorption rate, but not thepCO(2)nor its interaction with other factors studied. Oxygen consumption was significantly affected bypCO(2), temperature and time. Scope for growth was only significantly affected by time; despite this, the highest values were observed for individuals subject to to 20 degrees C and to similar to 1000 mu atmpCO(2). In this study,Ostrea chilensisshowed high phenotypic plasticity to respond to the high levels of temperature andpCO(2)experienced in its habitat as no negative physiological effects were observed. Thus, the highly variable conditions of this organism's environment could select for individuals that are more resistant to future scenarios of climate change, mainly to warming and acidification.