USF St. Petersburg campus Master's Theses (Graduate)
Dendrogyra cylindrus (Pillar Coral) of the Florida Reef Tract: An Ex Situ Growth Study, and In Situ – Ex Situ Bacterial Assemblage Assessment
Major Professor: Heather Judkins, Ph.D.
Mya Breitbart, Ph.D.
Cynthia Lewis, Ph.D.
University of South Florida St. Petersburg
June 28, 2020
The iconic Pillar Coral, Dendrogyra cylindrus, occurs exclusively in the Greater Caribbean and is the only species in its genus. Until the last decade, this stony coral species was notably under-studied by scientists. The drastic decline in this species prompted the formation of the ‘Pillar Coral Genetic Rescue Project’ (Jan. 2016) to provide long term care, growth, and emergency treatment for fragments of D. cylindrus – joined by the Florida Aquarium in August 2016. In contribution to the conservation efforts of this species, this research examines the ex situ growth rate for the species and compares the microbial community composition of D. cylindrus between an ex situ nursery and in situ reef sites, focusing on one group of microorganisms, bacteria. Coral fragments housed at the Center for Conservation, a Florida Aquarium facility in Apollo Beach, Florida, as well as samples previously collected from the reef, were used for this study. Chapter Two focuses on the assessment of the annual growth rate of ex situ D. cylindrus fragments using buoyant weight. The only recorded attempt to establish a growth rate for D. cylindrus examined linear extension (cm/ year) while measuring buoyant weight (g/ year) was expected to yield a more accurate growth rate. This is the first account of an ex situ growth rate for this species. Over 12 months, the average growth for 24 D. cylindrus fragments was 26.85 (± 13.12 SD) g/year. A significant difference in growth was detected between the genotypes, particularly D1380 - D1105 (p=0.004), which were originally collected from the Middle Keys region of the Florida
Reef Tract. Chapter Three covers the first assessment of the bacterial assemblage of D. cylindrus polyps ex situ and is the first analysis of its type comparing in situ and ex situ D. cylindrus fragments. Forty-two samples yielding 5,551unique bacterial amplicon sequence variants (ASVs) were identified across the two locations (in situ and ex situ). The dominant phyla identified remained consistent with common phyla associated with corals in the Atlantic Ocean. At a 50% minimum prevalence, the 49 core taxa of the combined 42 samples was 31% Proteobacteria, 20% Firmicutes, 12% Actinobacteriota, 10% Bacteroidota, 8% Campilobacterota (Campylobacterota; previously epsilonproteobacteria), 4.1% Cyanobacteria, 2% Patescibacteria, and 12% were not classified to phylum. Alpha and Beta diversity indices indicated a significant difference in the microbial community composition between the in situ and ex situ locations. Τhe Caribbean contains the largest proportion of corals that are considered to be at high risk of extinction, and recent surveys have declared D. cylindrus of The Florida Reef Tract to be functionally extinct in the wild. In cooperation with The Florida Aquarium, this research contributes to the advancement of ex situ efforts for progressing coral research and mitigating the modern ecological damage of The Florida Reef Tract.
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Hetzler, Aubrey E., "Dendrogyra cylindrus (Pillar Coral) of the Florida Reef Tract: An Ex Situ Growth Study, and In Situ – Ex Situ Bacterial Assemblage Assessment" (2020). USF St. Petersburg campus Master's Theses (Graduate).
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Conservation Biology Department of Biological Sciences College of Arts and Sciences University of South Florida St. Petersburg