Temperature stress and disease drives the extirpation of the threatened pillar coral, Dendrogyra cylindrus, in southeast Florida

Abstract

Rare species population dynamics can elucidate the resilience of an ecosystem. On coral reefs, climate change and local anthropogenic stressors are threatening stony coral persistence, increasing the need to assess vulnerable species locally. Here, we monitored the threatened pillar coral, Dendrogyra cylindrus, population in southeast Florida, USA, in relation to consecutive heat stress events in 2014 and 2015. In the fall of each year, D. cylindrus colonies bleached following intense thermal stress and by June 2020 all monitored colonies died from a white-syndrome type disease. This resulted in the ecological extinction of D. cylindrus in the Southeast Florida Coral Reef Ecosystem Conservation Area (ECA). White-syndrome type disease was first seen in February 2014 on four colonies (19% prevalence) near the major international port, Port Everglades and disease prevalence peaked in fall 2015 (58%). Disease prevalence increased with maximum water temperature, while disease related mortality increased with mean water temperature. Our findings suggest that thermal stress exacerbated underlying stony coral disease, resulting in an outbreak contributing to the ecological extirpation of D. cylindrus in the ECA. We suggest that stony coral resilience is severely compromised by chronic environmental disturbance which hinders community recovery.

Multi-Variate Analyses of Coral Mortality From the 2014–2015 Stony Coral Tissue Loss Disease Outbreak Off Miami-Dade County, Florida

“…Although it is clear that extremely warm water temperatures preceded the onset of SCTLD throughout southeast Florida (Manzello, 2015;Precht et al, 2016;Walton et al, 2018;Jones et al, 2021), once the disease outbreak was spreading regionwide there was no clear link between the time of year, temperature, and initiation of SCTLD (Muller et al, 2020). Thus, water temperatures at the time of disease onset may be irrelevant to its initiation.…”

“…Thus, while increased temperature and diminished water quality were the likely stressors that triggered this disease outbreak in Miami-Dade County in the fall of 2014 (see Staley et al, 2017;Walton et al, 2018;Gintert et al, 2019;Sinigalliano et al, 2019;Whitall et al, 2019;Jones et al, 2021), it is still important to know the origin of the purported pathogen(s). This is especially important for developing disease amelioration strategies for reefs impacted by SCTLD (Precht, 2021).…”

“…Whatever the root cause, the reality is that the ongoing SCTLD epizootic that started off in Miami-Dade County in 2014 has changed the community structure and potentially the ecosystem dynamics of the entire Florida reef tract (Aeby et al, 2017;Hayes et al, 2017;Lunz et al, 2017;Neely, 2018;Ruzicka, 2018;Walker, 2018;Sharp et al, 2020;Jones et al, 2021;Williams et al, 2021) and is now affecting reefs at sites throughout the Caribbean (AGRRA, 2021). Given the high SCTLD-based mortality rates observed in this study and across Florida as well as the current diminished capacity for coral recovery regionwide (Moulding, 2005;Smith et al, 2013;van Woesik et al, 2014), the future of reef-building stony coral communities in Florida and the Caribbean is unsettling to say the least.…”

“…The initial outbreak of SCTLD in Southeast Florida is arguably one of the most lethal coral disease events ever recorded on a contemporary coral reef system. In a few short years, the ecological extirpation of many key species has fundamentally changed the way these reefs look and function (Precht et al, 2016;Walton et al, 2018;Gintert et al, 2019;Jones et al, 2021;Neely et al, 2021a). The resulting community shift caused by SCTLD is just the last in a series of regional coral mortality events responsible for a multi-decadal trend of reefs being dominated by a few small, highly ephemeral, stress-tolerant species (Green et al, 2008;Burman et al, 2012;Smith et al, 2013;Toth et al, 2014Toth et al, , 2019Estrada-Saldívar et al, 2019).…”

“…These 2016 data were not included in this analysis but are briefly reviewed in the Discussion. We intentionally avoided the 2016 one-off survey so our data would not be confounded by other natural events that transpired in the year after the cessation of dredging activities (such as a second major coral bleaching event observed in the summer of 2015; National Oceanic Atmospheric Administration, 2015b; Jones et al, 2021;Neely et al, 2021a), instead focusing on causes of coral stress and mortality that occurred immediately before, during, and after the Port Miami project when monitoring was occurring on a regular basis.…”