Modelling coral reef futures to inform management: can reducing local-scale stressors conserve reefs under climate change?

Perry M Aliño,Georgina G Gurney,Rollan C Geronimo,Craig R Johnson,Jessica Melbourne-Thomas

doi:10.1371/journal.pone.0080137

Abstract

Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef systems.

Highlights

Coral reefs are of immense natural and anthropocentric value
Since there were no materials transferred outside the country, there was no need for a gratuitous permit for materials transfer from the Bureau of Fisheries and Aquatic Resources (BFAR) of the Department of Agriculture (DA)
We investigate NS6F and NS6B interactions terms which were significant in both the PERMANOVA and PERMDISP, which affords some insights into the predictability of future reef condition under alternative management and bleaching scenarios

Summary

Introduction

Coral reefs are of immense natural and anthropocentric value. Aside from boasting the highest diversity of all marine ecosystems [1], coral reefs provide a wealth of ecosystem goods and services to millions of people in more than 100 tropical countries [2,3]. Coral reefs are in decline worldwide [4,5], and given the present momentum of human population growth, resource use and the imminent threat of climate change, this decline is likely to be exacerbated [6]. Coral reef degradation is driven by a myriad of stressors, which are largely a result of marine- and land-based anthropogenic activities such as fishing, coastal development, and aquaculture [7]. Climate change has emerged as a principal threat to coral reefs [8,9]. There is growing evidence that the vulnerability of coral reefs to the effects of climate change is increased by chronic, local-scale stressors [10,11] and that the cumulative effect of these stressors may be synergistic [12,13]

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Conclusion