Biophysical and physiological processes causing oxygen loss from coral reefs.

Area of Science:

• Marine Biology
• Ecology
• Microbiology

Background:

• Coral reefs face deoxygenation, a threat linked to microbial activity.
• The role of microbial metabolism and oxygen loss in reef deoxygenation requires further investigation.

Purpose of the Study:

• To test the hypothesis that microbial oxygen consumption causes reef deoxygenation.
• To analyze reef microbial and primary producer oxygen metabolisms.

Main Methods:

• Metagenomic analysis of microbial communities.
• In vitro incubations of bacteria with primary producer exudates.
• Experiments measuring dissolved and gaseous oxygen in microbial-ecosystem interactions.
• Modeling oxygen production and loss rates.

Main Results:

• Fleshy algae stimulate incomplete carbon oxidation in heterotrophic bacteria, increasing their size and abundance.
• Bacteria incubated with algae consumed 10 times more oxygen than those with corals.
• Oxygen loss occurred via ebullition due to heterogeneous nucleation on algae surfaces.
• Model predictions indicated microbes and ebullition can account for up to 67% of gross benthic oxygen production.

Conclusions:

• Microbial respiration and ebullition are critical drivers of reef deoxygenation.
• Algal dominance in reefs exacerbates oxygen loss and deoxygenation.
• Understanding these processes is vital for coral reef conservation.