Ocean acidification and coral reefs: effects on breakdown, dissolution, and net ecosystem calcification

Area of Science:

• Marine Biology
• Oceanography
• Ecosystem Science

Background:

• Coral reefs are vital habitats, supporting biodiversity and providing ecosystem services.
• Ocean acidification (OA) poses a significant threat to coral reefs by impacting calcium carbonate (CaCO(3)) production and dissolution.
• OA may shift coral reefs from net accretion to net erosion, jeopardizing their structure and function.

Purpose of the Study:

• To review how bioerosion, CaCO(3) dissolution, and net ecosystem calcification (NEC) change with OA.
• To critically evaluate the relationship between NEC and seawater aragonite saturation state (Ω(a)).
• To propose a biogeochemical monitoring tool for assessing OA effects on coral reefs.

Main Methods:

• Review of existing estimates for bioerosion, CaCO(3) dissolution, and NEC.
• Critical evaluation of the correlation between NEC and Ω(a).
• Proposal of a novel monitoring approach using dissolved inorganic carbon and total alkalinity ratios.

Main Results:

• OA is projected to decrease CaCO(3) production and increase bioerosion and dissolution rates.
• The relationship between NEC and Ω(a) is complex and requires further critical evaluation.
• Standardized NEC rates and altered dissolved inorganic carbon/total alkalinity ratios show promise as OA monitoring indicators.

Conclusions:

• Coral reef persistence is threatened by OA, potentially leading to ecosystem degradation.
• A standardized biogeochemical approach, combining NEC and carbonate chemistry, can effectively monitor OA impacts.
• This monitoring tool can help understand and mitigate the negative consequences of OA on coral reef ecosystems.