Date of Award

Spring 5-2023

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Mark J. Butler

Committee Member

Eric L. Walters

Committee Member

Rochelle D. Seitz


Coral reef degradation, resulting from anthropogenic factors and natural change, has resulted in drastically reduced coral cover causing a phase shift from coral-dominated to macroalgae-dominated reefs, especially in the Caribbean. An important contributor to this shift is the loss of herbivores due to overfishing and the disease-related reduction of the long-spined sea urchin (Diadema antillarum) population during the 1980s. However, recent studies conducted in the Florida Keys have shown that increasing the abundance of herbivorous, native Caribbean king crabs (Maguimithrax spinosissimus) on reefs, can reduce the cover of nuisance algae and improve coral recruitment. Maguimithrax spinosissimus grazing rates surpass all grazers except the stoplight parrotfish (Sparisoma viride) and they consume some types of algae that possess physical and chemical defenses and are avoided by most fish grazers. These characteristics make M. spinosissimus an excellent candidate for coral reef restoration, but their low natural density poses a bottleneck to their widespread use. Because of their year-round reproduction, brief larval period, and quick growth, I hypothesize that cultivating M. spinosissimus in saltwater quarries would be an economically efficient method for generating sufficient numbers of crabs for coral reef restoration. I surveyed 16 land-locked saltwater quarries in the Florida Keys where M. spinosissimus already occurs or could potentially be introduced and compared those data to those of nearshore reefs. The majority of quarries displayed stratification of the water column, with dissolved oxygen and pH decreasing with depth whereas temperature and salinity increased with depth. Structural complexity was greater in coral reef environments, but percent algal cover was higher in quarries presumably due to low abundance of herbivores. There was no difference in the population size structure, fecundity, relative predatory mortality, and relative health (hemolymph protein index) of crabs in quarries when compared to those living on coral reefs. These results indicate that mariculture of M. spinosissimus is likely feasible in saltwater quarries.


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