People and the changing nature of coral reefs

Coral reefs are biodiverse and productive ecosystems but are threatened by local and global stresses. The resulting loss of coral reefs is threatening coastal food and livelihoods. Climate projections suggest that coral reefs will continue to undergo major changes even if the goals of the Paris Agreement (Dec 2015) are successfully implemented. Ecological changes include modified food webs, shifts in community structure, reduced habitat complexity, decreased fecundity and recruitment, changes to fisheries productivity/opportunity, and a shift in the carbonate budget of some ecosystems toward dissolution and erosion of calcium carbonate stocks. Broad estimates of the long-term (present value) of services provided by the ocean's ecological assets exist and are useful in highlighting the value of reefs yet must be contextualised by how people respond under ecosystem change. The dynamic nature of the relationship between people, economies, and the environment complicates estimation of human consequences and economic outcomes of changing environmental and ecological capital. Challenges have increased given lack of baseline data and our inability to predict (with any precision) how people respond to changing coral reef conditions, especially given the variability, flexibility, and creativity shown by human communities and economies under change. Here, we explore how the changes to the three-dimensional structure of coral reefs affect benefits for people, specifically coastal protection, fisheries habitat, and tourism. Based on a review of available data and literature, we make a series of key recommendations that are required to better understanding of how global change will affect people dependent on coral reefs. These include: (1) baseline studies and frameworks for understanding human responses to climate change within complex social and ecological setting such as coral reefs, (2) better tools for exploring environmental benefits, markets, and financial systems faced by change, and (3) the integration of these insights into more effective policy making