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

Abstract

BackgroundCoral 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 FindingsReef 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 <11°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/SignificanceThe 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.

MODIS-derived spatiotemporal water clarity patterns in optically shallow Florida Keys waters: A new approach to remove bottom contamination

“…This plume is clearly visible in true color satellite imagery. It is possible that the extreme cold event in January 2010 (see Barnes & Hu, in press;Barnes et al, 2011;Lirman et al, 2011) caused mortality of Everglades flora and subsequent nutrient release (Duever et al, 1994). If advected into the FRT region, colored dissolved organic matter (CDOM) from the plant decay or phytoplankton blooms stimulated by the influx of nutrients could cause the anomalously high K d (488) observed.…”

“…Coral cover within the FRT has precipitously declined over the last several decades (Andréfouët et al, 2002;Hughes, 1994;Palandro et al, 2001Palandro et al, , 2008. These changes have been attributed to extreme temperature events (Jaap, 1985;Lirman et al, 2011;Warner et al, 1999), as well as changes in water quality (Hu et al, 2003;Lapointe et al, 2004) resulting from local anthropogenic activities (LaPointe & Clark, 1992) or exogenous sources such as Florida Bay (Smith, 1994) and Mississippi River (Hu et al, 2005;Ortner et al, 1995). Seagrass density in the region has also decreased, most often attributed to algal blooms and epiphyte buildup (LaPointe & Clark, 1992).…”

Water clarity patterns in South Florida coastal waters and their linkages to synoptic-scale wind forcing

“…Elevated Kd and KDI values (>3) were evident for an extended period from mid-January through March, 2010. The event occurred during a time of active and severe weather including a cold-air outbreak and cold-snap event of extreme duration, causing region-wide air and sea surface temperatures to drop well below tolerance levels for multiple animal species (Pirhalla et al, 2014;Roberts et al, 2014;Lirman et al, 2011).…”

High Latitude Corals Tolerate Severe Cold Spell

“…In the marine environment, extreme temperature events can be particularly detrimental with potentially wide ranging and catastrophic impacts (e.g., Southward and Burrows, 1995;Garrabou et al, 2009;Lirman et al, 2011;Wernberg et al, 2016). Both marine heatwaves (MHW's) and cold spells (MCS's) have only recently been defined in the literature (MHW's; Hobday et al, 2016, MCS;Schlegel et al, 2017).…”