Anthropogenic carbon dioxide (CO₂) emissions are causing ocean acidification and ocean warming; however, the synergistic effects of these stressors on giant clams are completely unknown. Juveniles of the fluted giant clam, Tridacna squamosa Lamarck, 1819, were exposed to present-day control seawater (416 µatm pCO₂) and seawater treated with CO₂ to simulate ocean conditions predicted for the next 50–100 years (622 µatm pCO₂ and 1019 µatm pCO₂). These CO₂ treatments were cross-factored with seawater temperatures of ~28.5 °C, ~30.0 °C and ~31.5 °C. The majority of mortality occurred between 40 and 60 days. Survival of juveniles decreased with increasing pCO₂ and decreased with increasing seawater temperature. The combination of the highest pCO₂ and both the moderate and highest seawater temperatures resulted in the lowest survival of <20 % indicating survival of T. squamosa could be reduced considerably at ocean conditions predicted to occur around the end of this century.

Additional keywords: climate change, carbon dioxide, high-CO₂, temperature, ecology, Cardiidae, Tridacninae, mollusc, bivalve, Bivalvia