Plastic response of the oyster Ostrea chilensis to temperature and pCO2 within the present natural range of variability.

Jorge M Navarro,Samanta Benítez,Oscar R Chaparro,Emilio Alarcón,Paola Villanueva,Rodrigo Torres,Natalia Rocha,Paola V Andrade-Villagrán,José A Fernández Robledo

doi:10.1371/journal.pone.0234994

Abstract

Estuaries are characterized by high fluctuation of their environmental conditions. Environmental parameters measured show that the seawater properties of the Quempillén estuary (i.e. temperature, salinity, pCO2, pH and ΩCaCO3) were highly fluctuating and related with season and tide. We test the effects of increasing temperature and pCO2 in the seawater on the physiological energetics of the bivalve Ostrea chilensis. Juvenile oysters were exposed to an orthogonal combination of three temperatures (10, 15, and 20°C) and two pCO2 levels (~400 and ~1000 μatm) 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, while pCO2 and the interaction between pCO2 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 the pCO2 nor its interaction with other factors studied. Oxygen consumption was significantly affected by pCO2, 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°C and to ~1000 μatm pCO2. In this study, Ostrea chilensis showed high phenotypic plasticity to respond to the high levels of temperature and pCO2 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.

Highlights

Increased pCO2 in the atmosphere alters the temperature and pH of marine habitats affecting marine life at global scales [1]
The values of temperature and salinity registered at the Quempillen estuary are agreeing with previous studies [28] for the same study area, where these authors registered that temperature reaches a maximum of 20 ̊C during low summer tide and a minimum of 8.6 ̊C at low winter tide
Several studies have demonstrated that reduction in carbonate ion concentration can affect the ability of marine organisms to produce and/or maintain calcium carbonate (CaCO3) calcareous structures [1]

Summary

Introduction

Increased pCO2 in the atmosphere alters the temperature and pH of marine habitats affecting marine life at global scales [1]. The interaction between elevated seawater pCO2 and high temperature can reduce the thermal tolerance window of an organism exposed to high CO2 levels [10]. There is evidence that many environmental stressors can act in synergistic, additive, and/or antagonistic ways to affect various physiological processes of marine organisms [20]. Some organisms exposed to high levels of CO2 have decreased thermal tolerance [21], yet increased temperature can counteract the effects of low pH [11,12,13,14,15,16,17,18,19,20,21,22]

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