Severe 2010 Cold-Water Event Caused Unprecedented Mortality to Corals of the Florida Reef Tract and Reversed Previous Survivorship Patterns

Background Coral reefs are facing increasing pressure from natural and anthropogenic stressors that have already caused significant worldwide declines. In January 2010, coral reefs of Florida, United States, were impacted by an extreme cold-water anomaly that exposed corals to temperatures well below their reported thresholds (16°C), causing rapid coral mortality unprecedented in spatial extent and severity. Methodology/Principal Findings Reef surveys were conducted from Martin County to the Lower Florida Keys within weeks of the anomaly. The impacts recorded were catastrophic and exceeded those of any previous disturbances in the region. Coral mortality patterns were directly correlated to in-situ and satellite-derived cold-temperature metrics. These impacts rival, in spatial extent and intensity, the impacts of the well-publicized warm-water bleaching events around the globe. The mean percent coral mortality recorded for all species and subregions was 11.5% in the 2010 winter, compared to 0.5% recorded in the previous five summers, including years like 2005 where warm-water bleaching was prevalent. Highest mean mortality (15%–39%) was documented for inshore habitats where temperatures were \u3c11°C for prolonged periods. Increases in mortality from previous years were significant for 21 of 25 coral species, and were 1–2 orders of magnitude higher for most species. Conclusions/Significance The cold-water anomaly of January 2010 caused the worst coral mortality on record for the Florida Reef Tract, highlighting the potential catastrophic impacts that unusual but extreme climatic events can have on the persistence of coral reefs. Moreover, habitats and species most severely affected were those found in high-coral cover, inshore, shallow reef habitats previously considered the “oases” of the region, having escaped declining patterns observed for more offshore habitats. Thus, the 2010 cold-water anomaly not only caused widespread coral mortality but also reversed prior resistance and resilience patterns that will take decades to recover

Citizen science benefits coral reef restoration activities

The abundance of corals has declined significantly over past decades, to the point where several reef-building species in the Caribbean are now listed as threatened. Active reef restoration has expanded exponentially to help recover degraded coral populations and the ecological services associated with healthy and complex reefs. While restoration practitioners now grow hundreds of coral genotypes from several species within coral nurseries and thousands of corals are outplanted onto degraded reefs annually, the cost of these activities continues to be a limiting factor. We describe a citizen science program, Rescue a Reef (RAR), which trains participants in reef restoration and provides unique, experiential learning opportunities to recover degraded coral reefs by propagating and transplanting threatened coral species. Between 2015–2017, 230 participants outplanted >1300 staghorn corals, showing that citizen scientists significantly contribute to reef restoration. Most importantly, corals outplanted by RAR participants showed the same survivorship as those outplanted by scientific experts. The direct benefits of using citizen scientists for restoration are enhanced when the educational opportunities offered by these expeditions are considered. Results from our survey showed significant improvements in coral reef ecology and restoration knowledge for RAR participants. Thus, the growing field of reef restoration based on the coral gardening method offers a unique opportunity for participatory public engagement. By participating in these programs, citizen scientists can go beyond data collection to active restoration of degraded resources