Testing Spatial Management Strategies for Hawaii's Future Reefs: A Biophysical, Metacommunity Approach

Abstract

Coral reefs are invaluable resources in tropical communities, and support the cultural and substantial livelihoods of millions of coastal peoples. Reefs are home to a massive proportion of earth’s biodiversity, and form the basis of commercially valuable fisheries and tourism industries. However, reefs are globally in decline, and it is in the interest of marine resource managers to understand and modulate impacts of climate- and human-induced effects on the continued resilience of their reef ecosystems. Simulation models have proven to be useful, though not perfect, tools to test and evaluate potential futures of reef ecosystems at a variety of spatial scales. These are most effective when incorporating a broad set of biological, climactic and environmental data, and can be adapted to various regions. This thesis presents the development, validation, and application of a pre-existing biophysical coral reef model, CORSET (Coral Reef Scenario Evaluation Tool) to a novel system, the Main Hawaiian Islands (MHI). The model was originally developed by Jessica Melbourne-Thomas and colleagues at the University of Tasmania as a portable framework to address biophysical processes on coral reefs across multiple spatial scales1. The model incorporates local ecology, larval connectivity, and anthropogenic and environmental forcings across an array of differential equations, run on a desktop computer and visualized using spatial or graphical software. It is a decision support tool for visualizing reef futures at regional scales in the order of 102 -103 km. This study applies and demonstrates the portability of the CORSET model, and applies a test-case to examine potential reef scenarios under alternative climate, land-use and fishing protection regimes. The results hold implications for simulation testing in reef ecology and decision-support for marine fisheries management. The study conclusion also provides simulative evidence against the common paradigm that top-down management strategies will be the most effective in preserving coral cover.