Freeman, L. A., J. A. Kleypas and A. J. Miller, 2013:
Coral reef habitat response to climate change scenarios
PLoS ONE, 8, e82404. doi:10.1371/journal.pone.0082404.
Coral reef ecosystems are threatened by both climate change and direct anthropogenic stress. Climate change will
alter the physico-chemical environment that reefs currently occupy, leaving only limited regions that are conducive to
reef habitation. Identifying these regions early may aid conservation efforts and inform decisions to transplant
particular coral species or groups. Here a species distribution model (Maxent) is used to describe habitat suitable for
coral reef growth. Two climate change scenarios (RCP4.5, RCP8.5) from the National Center for Atmospheric
Research.s Community Earth System Model were used with Maxent to determine environmental suitability for corals
(order Scleractinia). Environmental input variables best at representing the limits of suitable reef growth regions were
isolated using a principal component analysis. Climate-driven changes in suitable habitat depend strongly on the
unique region of reefs used to train Maxent. Increased global habitat loss was predicted in both climate projections
through the 21st century. A maximum habitat loss of 43% by 2100 was predicted in RCP4.5 and 82% in RCP8.5.
When the model is trained solely with environmental data from the Caribbean/Atlantic, 83% of global habitat was lost
by 2100 for RCP4.5 and 88% was lost for RCP8.5. Similarly, global runs trained only with Pacific Ocean reefs
estimated that 60% of suitable habitat would be lost by 2100 in RCP4.5 and 90% in RCP8.5. When Maxent was
trained solely with Indian Ocean reefs, suitable habitat worldwide increased by 38% in RCP4.5 by 2100 and 28% in
RCP8.5 by 2050. Global habitat loss by 2100 was just 10% for RCP8.5. This projection suggests that shallow tropical
sites in the Indian Ocean basin experience conditions today that are most similar to future projections of worldwide
conditions. Indian Ocean reefs may thus be ideal candidate regions from which to select the best strands of coral for
potential re-seeding efforts.