Separate and combined effects of elevated pCO

Area of Science:

• Marine Biology
• Climate Change Science
• Ecology

Background:

• Coral reefs face significant threats from ocean acidification (OA) and ocean warming (OW).
• Limited research exists on the combined impacts of OA and OW on coral species.
• Acropora digitifera and Montipora digitata exhibit differential responses to environmental changes.

Purpose of the Study:

• To investigate the individual and combined effects of OA and OW on Acropora digitifera and Montipora digitata.
• To determine the primary stressor impacting coral health under combined OA and OW conditions.
• To predict future shifts in coral species abundance in Okinawa.

Main Methods:

• Experimental manipulation of ocean acidification and warming levels.
• Assessment of coral mortality rates under different environmental conditions.
• Measurement of coral calcification rates.

Main Results:

• Ocean warming had a more substantial impact on both A. digitifera and M. digitata than ocean acidification.
• A. digitifera demonstrated higher vulnerability to ocean warming compared to M. digitata.
• The combined effects of OA and OW were additive, with OW identified as the main stressor driving increased mortality and reduced calcification.

Conclusions:

• Ocean warming is a more critical threat to these coral species than ocean acidification alone.
• The additive effects of OA and OW pose a significant risk to coral reef ecosystems.
• Future projections indicate a potential increase in M. digitata abundance and a decrease in A. digitifera cover in Okinawa.