Sewage pollution: mitigation is key for coral reef stewardship

Area of Science:

• Marine Biology
• Environmental Science
• Ecology

Background:

• Coral reefs are experiencing a global decline.
• Land-derived pollution, particularly sewage, is a significant driver of this deterioration.
• Sewage discharge impacts at least 104 out of 112 surveyed reef geographies.

Purpose of the Study:

• To review the evidence on sewage as a stressor to coral reefs.
• To characterize sewage as a multiple stressor, not a single one.
• To highlight the need for increased investment in sewage pollution mitigation strategies.

Main Methods:

• Literature review of published studies on sewage impacts on coral reefs.
• Analysis of the components within sewage and their individual and combined effects.
• Assessment of the geographical extent of sewage discharge near coral reefs.

Main Results:

• Sewage is a multiple stressor, comprising freshwater, nutrients, pathogens, endocrine disruptors, suspended solids, sediments, and heavy metals.
• These components can individually impair coral growth and reproduction.
• Synergistic effects between sewage components and other stressors can escalate negative impacts.

Conclusions:

• Sewage pollution is a pervasive and severe threat to coral reefs worldwide.
• Field studies, though limited, indicate significant negative effects of sewage on coral reefs.
• Urgent investment in threat-abatement strategies is necessary to mitigate sewage pollution and protect coral reefs.