HCNSO Student Theses and Dissertations

Defense Date


Document Type


Degree Name

M.S. Marine Biology


Oceanographic Center

First Advisor

David S. Gilliam

Second Advisor

Bernhard Riegl

Third Advisor

Richard E. Dodge


The colonial zoanthid Palythoa caribaeorum (Cnidaria, Zoanthidea) (Duchassaing and Michelotti 1861) is a major benthic component of most Caribbean reefs and is an extremely aggressive spatial competitor (Suchanek and Green 1981). This study looks at annual visits to 16 permanent monitoring sites over 3 reef designations (Inshore Ridge Complex, Middle Reef, and Outer Reef) in Broward County, Florida from 2002-2006. The data obtained in this study fills an informational void regarding the role of zoanthids in the southeast Florida reef benthic community. The study was conducted in two parts. Part One used digital imagery analysis to quantify the spatial cover of the Palythoa population present across the study area. The highest percent live cover sites were located in the Inshore Ridge Complex, suggesting that the more dense Palythoa populations are close to shore. Part Two used digital analysis data to determine if it was possible to create a size class transition matrix model that could accurately model the population distribution of such a dynamic organism. To test the accuracy of the model, the predicted population distribution of the model and the actual observed distribution from the digital image analysis were analyzed. A Chi-square test determined that the model successfully predicted size class distribution frequency of all treatments (All Sites, High Cover Sites, Low Cover Sites, and the 3 reef tracts) for all years (2002-2006) with the exception of 3 (Low Cover, Middle Reef, and Outer Reef) of the 6 treatments in 2005. Southeast Florida experienced extremely severe hurricane seasons in 2004 and 2005, and the data suggests that the population distribution at the 3 lower cover (farther from shore) sites were disturbed. Sensitivity and elasticity analyses were run on appropriate results to examine which size class transitions contribute most to population stability. Although it possesses the ability to outgrow stony corals (and almost all other sessile invertebrates), the current study suggests that the Palythoa population in southeast Florida is generally maintaining size rather than over-growing the reef community. With the knowledge gained from this study, we know that it is possible to accurately model the population dynamics present in the southeast Florida Palythoa population.

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