Assessing coral reefs on a Pacific-wide scale using the microbialization score.

Area of Science:

• Marine biology
• Ecosystem dynamics
• Environmental science

Background:

• Coral reefs worldwide are declining, with the exact mechanisms remaining unclear.
• Increased microbial and viral loads, including pathogens, are potential unifying factors in reef decline.
• The 'microbialization' of coral reefs suggests a shift in ecosystem energy allocation towards microbes.

Purpose of the Study:

• To test the hypothesis that human activities alter reef energy budgets by shifting metabolic energy allocation between microbes and macrobes.
• To develop and validate a metric for assessing reef health and human impact on a regional scale.

Main Methods:

• Calculated basal metabolic rates for fish and microbial communities across 99 sites in the Pacific Ocean.
• Utilized established scaling relationships to predict metabolic rates.
• Derived the 'microbialization score' representing the microbial proportion of combined metabolic rates.

Main Results:

• A strong positive correlation was found between microbialization scores and human impact.
• Microbialization scores did not significantly correlate with ocean net primary production, chlorophyll-a, or total metabolic rate.
• Findings support the hypothesis of human-driven energy shifts from macrobes to microbes.

Conclusions:

• The microbialization score is a robust metric for assessing human impact on coral reef systems.
• Human activities significantly influence the energy dynamics within coral reef ecosystems.
• Understanding microbialization is key to addressing coral reef decline irrespective of oceanographic conditions.