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

Abstract

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 <11°C), resulting in the largest documented coral mass mortality event ever recorded in the Florida Keys. Physiological measurements demonstrated species‐specific thermal sensitivities to this environmental perturbation. Four common corals with narrow thermal tolerance, Acropora cervicornis, Orbicella annularis, O. faveolata, and Porites astreoides, sustained high mortality (>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.

Macroalgae reduces survival of nursery‐rearedAcroporacorals in the Florida reef tract

“…It is therefore difficult to target the best locations for long‐term success of outplanted Acropora corals because of the likely interactions among these variables, and the continued presence of stressors, including ocean warming that causes bleaching and coral disease (Precht et al ). Floridian reefs are also susceptible to cold‐water mortality events (Lirman et al 2011; Kemp et al ).…”

A review of subtropical community resistance and resilience to extreme cold spells

“…Similar to other climate extremes, extreme cold spells affecting the subtropics are capable of driving whole‐scale changes to ecosystem structure and function (Stone , Boucek and Rehage , Kemp et al. , Santos et al. ).…”

Investigating Sub-tropical Community Resistance and Resilience to Climate Disturbance

“…In both Florida and China, mortality of tropical species was observed from latitudes 19°N, and 29°N, to latitudes of 24°N and 28°N, respectively (Chen et al 2016;Stevens et al, 2016, Kemp et al 2016. Despite the large footprint of the area affected by extreme cold spells, tropical species and sub-tropical community resistance and resilience vary across space.…”

“…Decreases in the frequency of these events may also increase the population stability of threatened tropical species occurring within the sub-tropics (i.e., American crocodile; Mazzotti et al 2016), as well as increase habitat suitability in the sub-tropics for tropical species threatened by climate warming (Liu et al 2012;Kemp et al 2016). Regardless of the fate of extreme cold spells in the future, our special issue highlights key responses that we can expect subtropical systems to exhibit in light of these extreme events.…”

“…For instance, in coastal aquatic systems of South Florida, coral community resistance was largely a function of their distance to warm water ocean currents. Coral patches occurring in shallow waters away from tropical ocean currents experienced almost complete loss of habitat-forming hard corals, while reefs occurring in deeper waters adjacent to ocean currents experienced minimal change (Kemp et al 2016). In the Shark River estuary, the upstreamdownstream gradient in absolute low temperatures during these events was likely a function of the hydrology of the estuary.…”