Life after cold death: reef coral and coral reef responses to the 2010 cold water anomaly in the Florida Keys

Organismal and community-wide responses of reef-building corals are documented before and after a severe cold-water thermal anomaly that occurred in 2010 in the Florida Keys, USA. In January 2010 seawater temperatures dropped far below the normal minima (to 80%) on inshore reefs. In contrast, another common coral with a wide thermal tolerance, Siderastrea siderea, was not affected by this cold anomaly. We measured biomass, symbiotic algal densities (genus: Symbiodinium), chlorophyll a content, and maximum quantum efficiency of photosystem II for reef-building corals on a seasonal basis before and after the 2010 cold anomaly. Our data document a clear correspondence between physiological response, biomass levels, and survivorship among these five scleractinian coral species. These physiological findings are mirrored by in-shore benthic community monitoring data, which show the dramatic loss of the three cold-sensitive species and continued survival of the cold-tolerant species. Finally, we document recruitment and survival rates of newly settled reef-building corals on four inshore reefs, which experienced high coral mortality during the 2010 cold-kill. Interestingly, both a cold-tolerant species, S. siderea, and a cold-intolerant species, P. astreoides, were the most abundant species recruiting to these postdisturbance reefs.