Integrated Land-Sea Management Crucial for Coral Reef Survival

A foundational paper in Nature featured several ʻĀkoʻakoʻa scientific authors who collaborated to diagnose threats to West Hawaiʻi's coral reefs. Analysis for the study gave rise to the ʻĀkoʻakoʻa program, and serves as a blueprint for necessary interventions.

The paper shows that coastal areas, which are home to diverse marine ecosystems, face restructuring due to human impacts and climate change. This 20-year study in Hawaiʻi reveals the importance of integrated land–sea management for coral reef conservation.

Read the article in Nature here.

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Key findings from the paper:

Human Impacts: Population density near the ocean affects coral reefs. Land-based stressors like wastewater pollution combine with sea-based stressors, disrupting ecological feedbacks and causing coral bleaching.

Conservation Model: Traditional decentralized island stewardship contrasts with modern centralized governance. While local managers aim for integrated land–sea approaches, evidence supporting its efficacy is lacking.

20-Year Study: The 20-year dataset in Hawaiʻi analyzes land–sea impacts on coral reefs. Factors include urban runoff, nutrient loading, and fishing gear restrictions. Fish biomass metrics and environmental factors are also considered.

Reef Trajectories: Reefs showed diverse trajectories before the 2015 marine heatwave. Positive correlations between fish biomass and coral cover highlight the role of reef fish in promoting habitat suitability.

Coral Response to Heatwave: In 2015, a severe marine heatwave hit Hawaii. Coral response varied, with some reefs maintaining or increasing coral cover. Factors like phytoplankton biomass and low urban runoff reduced coral mortality.

Postdisturbance Recovery: Four years post-heatwave, reefs with low wastewater pollution and high amounts of scraper fish biomass showed higher reef-builder cover. Integrated land–sea management resulted in a three- to sixfold increase in reef-builder cover.

The study emphasizes the need for integrated land–sea management to support coral reef persistence. Simultaneously addressing local human impacts on both land and sea can mitigate coral loss during disturbances (like marine heatwaves) and enhance recovery potential. This approach, along with global emissions reductions, is crucial for coral reef ecosystems' adaptation and survival in a changing climate. The findings call for policy measures that couple land–sea targets to achieve effective coastal ocean conservation goals.