Abstract Summary
The decline of living coral throughout much of the Florida Reef Tract, with no sign of community recovery over the last several decades, has resulted in a substantial need for active coral restoration. However, much of the threats associated with coral mortality, such as high water temperatures and disease outbreaks, continue to occur unabated. Therefore, the preference to select and outplant corals resilient to these threats is a primary goal among many restoration practitioners. Our objective was to screen genotypes of Acropora cervicornis used for restoration for heat tolerance, disease resistance, and resilience to ocean acidification, and determine whether there were tradeoffs among these resilient traits. We conducted a series of wetlab experiments exposing five replicates of 12 - 20 different genotypes of A. cervicornis to high water temperature, ocean acidification conditions, and white band disease. We measured the physiological responses of the corals under these different environmental scenarios including their photosynthetic efficiency using Imaging Pulse-Amplitude-Modulation Fluorometry, buoyant weight, net photosynthesis and respiration using oxygen evolution measurements, and calcification using alkalinity anomaly techniques. Additionally, we quantified the microbiome of the corals to determine whether the Symbiodinium strain or the bacterial community influenced resilience to these threats. Our results indicate that the resilient traits tested were independent of each other and few genotypes may exist that are resilient to all three threats. Disease resistant genotypes had a significantly different bacterial community compared with disease susceptible genotypes, indicating that the microbiome plays a key role in host immunity. However, the Symbiodinium strain did not appear to influence either heat tolerance or resilience to ocean acidification. These results suggest that maintaining a high genetic diversity, while also thoughtfully incorporating genotypes that are heat tolerant, resistant to disease, and/or resilient to ocean acidification, should be a primary practice incorporated into coral restoration initiatives.
