Nutrient pollution disrupts key ecosystem functions on coral reefs

Area of Science:

• Marine Biology
• Ecology
• Oceanography

Background:

• Coral reefs face threats from nutrient pollution and changing pH.
• The interaction between nutrient pollution and pH on coral reef ecosystems is poorly understood.

Purpose of the Study:

• To investigate the combined effects of nitrate and phosphate on coral reef calcification and community production.
• To determine how nutrient enrichment influences pH variability and reef calcification under different substrate conditions.

Main Methods:

• A six-week experimental study involving nutrient addition (nitrate and phosphate).
• Measurement of net community calcification (NCC) and net community production (NCP) rates.
• Assessment of impacts on individual taxa and combined reef communities.

Main Results:

• Nutrient addition decreased NCC rates across all substrate types.
• Coral reef communities shifted from net calcification to net dissolution under elevated nutrient levels.
• Nutrients increased pH variability by altering photosynthesis and respiration rates.
• The relationship between NCC and aragonite saturation state was disrupted by nutrient enrichment.

Conclusions:

• Nutrient pollution directly and indirectly impacts coral reef calcification.
• Elevated nitrate and phosphate levels exacerbate coral reef vulnerability to ocean acidification.
• Nutrient pollution accelerates the transition of coral reefs from accretion to erosion.