Looe Key Reef / FDEP

Florida Study: Regional coral disease outbreak overwhelms impacts from a local dredge project

The novel result of this analysis is that climate-mediated coral disease mortality was more than an order of magnitude more deadly than even the largest marine construction project performed in the USA over the past decade.

MIAMI, Florida — Regional coral bleaching and disease outbreaks associated with increased sea temperatures associated with global
climate change are already changing the face of coral reefs throughout southeastern Florida. That is the conclusion of new research published in the Springer Journal Environmental Assessment and Management.

The study also suggests that effective local management alone is insufficient to stem the continued decline of coral populations. These thermal events continue to result in catastrophic levels of coral mortality and highlight the need to focus on conservation efforts that curb atmospheric
CO2 emissions.

“The documentation of the 2014-present white-plague disease (a.k.a. Stony Coral Tissue Loss Disease) outbreak in southeastern Florida
is a dramatic example of how the one – two punch of coral bleaching and disease can irrevocably change coral populations within a short period of time” said William Precht of Dial Cordy and Associates, Inc. one of the reports co-authors.

Precht also noted that “there have been a number of exaggerated claims regarding dredge-related mortality of corals associated with the PortMiami deepening project.”

He continues “while there was local injury to corals associated with the PortMiami dredge projects – the claims that hundreds
of millions of corals were killed by the project - made by individuals not involved in the day-to-day monitoring of these corals - just
don’t match the actual observations made in the field made by our scientific divers.” In total, there were > 10,800 dives performed by
our project scientists between 2013 and 2017.

During these dives, ~ 25,000 in situ observations were made of over 600 tagged corals.

In the laboratory, these in situ coral condition data were compared with ~ 75,000 corresponding still photographs for cross-verification
and validation. The results from both long-term compliance and post-construction biological monitoring at 30 individual sites from
throughout Miami-Dade County showed that while there clearly were project impacts, they were mostly local and ephemeral.
Specifically, coral mortality related to the project, while present, was also minimal (~2% of corals directly adjacent to the dredge

The greatest impacts associated with coral mortality are directly attributed to the catastrophic, regional coral disease
outbreak which resulted in a loss of about 30% of the regional coral population. The disease outbreak has affected at least 17 coral
species in Miami-Dade County. Dendrogyra cylindrus, Eusmilia fastigiata, Meandrina meandrites, and Dichocoenia stokesi were the
most heavily impacted coral species.

Several other coral species, including Colpophyllia natans, Pseudodiploria strigosa, Diploria labyrinthiformis, and Orbicella annularis have also been severely impacted by this regional conflagration. Similar observations by other researchers have also been made throughout the Florida reef tract. Importantly, there appears to be a strong phylogenetic preference to disease susceptibility and mortality patterns observed regionally, however, to-date a putative pathogen responsible for this epidemic has not been isolated.

The high prevalence of disease, the number of susceptible species, its transmissibility, and the high mortality of corals affected suggests this disease outbreak is arguably one of the most lethal ever recorded on a contemporary coral reef system. Reports of continued spread to other regions of the Caribbean is troubling indeed and may portend doom to a reef system already at risk. The one bright spot in this study was the finding that a few coral species were not susceptible to the disease event, thus being spared the devastation wrought by this coral killer. Understanding why these corals were so hardy may be a critical lynchpin in developing coral conservation and restoration strategies for the future.

Cite as: Gintert, B.E., Precht, W.F., Fura, R. et al. (2019) Regional coral disease outbreak overwhelms impacts from a local dredge
project Environ Monit Assess 191: 630.
Additional Reading

Precht,W. F. (2019). Failure to respond to a coral disease outbreak: potential costs and consequences. PeerJ Preprints, e27860v2.

Precht, W. F., Gintert, B. E., Robbart, M. L., Fura, R., & van Woesik, R. (2016). Unprecedented disease-related coral mortality in southeastern Florida.

Scientific Reports, 6, 31374.
Precht,W., Gintert, B., Fura,R., Precht,W., Rogers, K.,& Robbart, M. (2018b). Coral disease ravages reef-building corals throughout Southeast Florida.

Inside Ecology (April 5, 2018)
Precht, W. F., Gintert, B., Fura, R., Rogers, K., Robbart, M., & Dial, S. (2019). Miami harbor deep dredge project: a reappraisal reveals same results.
WEDA Dredging Summit & Expo ‘19 Proceedings, Chicago, IL (June 2019)

Contact: William F. Precht, (305) 924-4274;

See also. We finally know why Florida’s coral reefs are dying, and it’s not just climate change