Does body type really matter? Relating climate change, coral morphology and resiliency

Average sea temperatures in many tropical regions are rising approximately 1-2˚C per century, and are thought to be a major driver of increased frequency of coral bleaching. However, certain coral morphologies appear to be more resilient to changes in the environment, particularly to sea temperature variations resulting from global climate change. Although branching corals (e.g., Acropora cervicornis, A. palmata) are highly susceptible to coral bleaching, this morphology is commonly used in coral restoration efforts because of its fast growth rate. Massive corals show higher resistance and resilience to elevated temperature events than branching species, but are less common in coral nurseries. The objective of this study was to compare coral resilience among morphology types in Little Cayman, a remote tropical island with <200 inhabitants where it is possible to decouple environmental and anthropogenic stressors. Three morphological groups (branching, intermediary and massive) were surveyed at 17 sites to estimate the percent cover of each group. Temperature profiles were observed at six moorings around the island, allowing for direct comparison between sea surface temperature, sea temperature at the reef depths, and coral cover, per morphology. The relationship between coral morphological coverage and temperature variation at depth was assessed in the context of geographic variation around the island. Understanding the relationship between coral morphology and resilience to temperature variability will enhance current coral restoration practices by identifying which morphologies have the highest chance of long-term survivorship following outplanting, concurrently optimizing cumulative reef survivorship.