Defense Date

8-6-2020

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Brian Walker

Second Advisor

Francisco Pagan

Third Advisor

Bernhard Riegl

Keywords

Stony Coral Tissue Loss Disease, chlorinated epoxy, treatment, antibiotic ointment, Orbicella, temporal, outbreak

Abstract

Coral diseases appear to be more devastating than ever before. When a virulent disease ravages a coral ecosystem, it can significantly change the population’s demographics and cause local extinctions. Disease intervention response during such an event is impossible at a landscape scale, therefore priorities must be considered. Saving the largest, oldest colonies of reef-building species is a good choice due to their high fecundity and ecological function. Their size, as a proxy for age, is an indicator of their resistance to previous perturbations which may indicate higher fitness. Their size also provides habitat to many organisms and wave resistance in shallow water for shoreline protection. Saving these colonies is imperative to preserve present ecological functions and to prepare for future restoration. Condition assessments of ninety of the largest, healthiest-looking colonies in southeast Florida during the SCTLD were conducted recording live tissue area, colony size, and number of tissue isolates. Colonies were checked for disease and photographed monthly. If diseased, intervention was conducted which entailed covering diseased tissue margins with chlorinated epoxy and sometimes creating a trench in the skeleton between diseased and healthy tissue and filling it with chlorinated epoxy. Treatment success generally went down over time and varied by treatment method and coral species. Methods were most effective on Orbicella spp. (75%) and less effective on the limited number of treated Montastraea cavernosa (37%) colonies. Seven of the thirty-eight treated colonies did not respond favorably to intervention treatments. The number of new treatments varied monthly and was highest at the onset of rainy season and the warmest periods in late summer. After field-testing the effectiveness of antibiotic treatments, all treatments on the infected Large Corals were switched to antibiotic ointment in August 2019. This showed higher success for Orbicella spp. (88.3%) and much higher success for Montastraea cavernosa (73.7%) colonies. The low success of the chlorinated epoxy treatments lead to the termination of this method, continuing, disease treatments will be treated solely with antibiotic ointment. Monitoring and intervention efforts have shown these colonies continue to get disease periodically, which if not treated will lead to colony mortality. New infections could be due to environmental stressors (e.g. salinity, temperature, dissolved organic carbon) as well as adaptations and genetic variations between and within species. Observed infection rates may correspond to increases in certain water quality metrics therefore it is important to investigate temporal infections of the large corals with temporal changes in water quality as well as collect cores and tissue samples of our Large Coral inventory to identify the cause of infection rate differences between species and individuals.

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