Seawater Acidification and Elevated Temperature Affect Gene Expression Patterns of the Pearl Oyster Pinctada fucata

Wenguang Liu,Jianshi Lin,Xiande Huang,Maoxian He,Inés Álvarez

doi:10.1371/journal.pone.0033679

Abstract

Oceanic uptake of anthropogenic carbon dioxide results in decrease in seawater pH and increase in temperature. In this study, we demonstrated the synergistic effects of elevated seawater temperature and declined seawater pH on gene expression patterns of aspein, calmodulin, nacrein, she-7-F10 and hsp70 in the pearl oyster Pinctada fucata. Under ‘business-as-usual’ scenarios, four treatments were examined: (1) ambient pH (8.10) and ambient temperature (27°C) (control condition), (2) ambient pH and elevated temperature (+3°C), (3) declined pH (7.70) and ambient temperature, (4) declined pH and elevated temperature. The results showed that under warming and acidic seawater conditions, expression of aspein and calmodulin showed no significant differences among different time point in condition 8.10 T. But the levels of aspein and calmodulin in conditions 8.10 T+3, 7.70 T and 7.70 T+3, and levels of nacrein, she-7-F10 in all the four treatments changed significantly. Low pH and pH×temperature interaction influenced the expression of aspein and calmodulin significantly after hours 48 and 96. Significant effects of low pH and pH×temperature interaction on the expression of nacrein were observed at hour 96. The expression level of she-7-F10 was affected significantly by pH after hours 48 and 96. The expression of hsp70 was significantly affected by temperature, pH, temperature×pH interaction at hour 6, and by temperature×pH interaction at hour 24. This study suggested that declined pH and pH×temperature interaction induced down regulation of calcification related genes, and the interaction between declined seawater pH and elevated temperature caused up regulation of hsp70 in P. facata. These results demonstrate that the declined seawater pH and elevated temperature will impact the physiological process, and potentially the adaptability of P. fucata to future warming and acidified ocean.

Highlights

Increasing concentrations of CO2 in the atmosphere are causing the ocean to become warmer and acidify [1]
This study investigates the synergistic effects of seawater warming and declined pH on gene expression patterns of calmodulin, nacrein, aspein, she-7-F10 and hsp70 in P. fucata to provide the first hand molecular evidence to evaluate the mechanisms for marine mollusc to response to elevated pCO2 seawater and temperature
Total alkalinity (TA) and salinity showed no clear change between treatments throughout the experiment

Summary

Introduction

Increasing concentrations of CO2 in the atmosphere are causing the ocean to become warmer and acidify [1]. Ocean absorbing of emitted CO2 lead to profound changes in the seawater carbonate chemistry with decrease in calcite, aragonite saturation state and seawater carbonate ions. These changes have been identified as a great threat to marine organisms, to calcifying organisms [5,6]. Effects of ocean acidification on calcification of marine organisms have been a focus in recent studies [7]. Decreasing in seawater pH has negative effects on calcification rate of organisms like coral Stylophora pistillata [8], echinoderm Amphiura filiformis [9] and molluscs Limacina helicina and Crassostrea gigas [10,11]. Marine organisms’ response to carbonate system variations is diverse

Methods

Results

Conclusion