MEPS 235:117-126 (2002)  -  doi:10.3354/meps235117

Density, spatial distribution and size structure of sea urchins in Florida Keys coral reef and hard-bottom habitats

Mark Chiappone1,*, Dione W. Swanson2, Steven L. Miller1

1Center for Marine Science Research and NOAA¹s National Undersea Research Center, University of North Carolina at Wilmington, 515 Caribbean Drive, Key Largo, Florida 33037, USA
2Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA

ABSTRACT: The 1983-84 Caribbean-wide mortality of the long-spined sea urchin Diadema antillarum Philippi was followed by a 2nd mortality event during 1991 in the Florida Keys. Pre-mortality sea urchin densities were up to 5 ind. m-2 and the large scale decline of D. antillarum is considered to be 1 factor affecting community dynamics of Florida Keys reefs. During 1999-2000, we surveyed 125 sites using a stratified random sampling design in shallow-water coral reef and hard-bottom habitats. Strip transects were sampled to assess density, habitat utilization and size structure patterns among habitat types, regional sectors and between fished and protected areas. Nearly 17 yr after the mass mortality, D. antillarum has not recovered to pre-1983 levels, with current densities no greater than 0.05 ind. m-2, and small test sizes (1 to 2 cm) dominate. Other sea urchins such as Eucidaris tribuloides (Lamarck) and Echinometra viridis Agassiz show density and habitat distribution patterns similar to historical observations.

KEY WORDS: Coral reefs · Florida Keys · Herbivory · Marine reserves · Population density · Recruitment · Sea urchins · Size structure

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