Genetic structure of natural and broodstock populations of the long-spined sea urchin, Diadema antillarum, throughout the Florida Keys

Abstract

Caribbean populations of the long-spined sea urchin, Diadema antillarum (Philippi, 1845), have undergone two mass mortality events since the 1980s that have caused 93%–100% of individuals on any given reef to perish. Subsequently, coral recruitment and survival declined, in part due to algal overgrowth and an increase in secondary metabolites associated with macoalgae. For long-term macroalgal biomass removal, supplementation of D. antillarum via translocation, captive-rearing and release, or both, must be considered. This project aimed to (1) compare genetic diversity of Diadema antillarum (Philippi, 1845) from six reef locations in south Florida ranging from Biscayne National Park to the Dry Tortugas, and (2) determine whether two broodstock populations of mixed ancestry contain variation indicative of natural Florida populations. We found little genetic differentiation among natural locations and between natural and broodstock populations (highest pairwise F ST was 0.0066). Moreover, genetic diversity was similar among all natural and broodstock populations (allelic richness and heterozygosity ranged from 22.6–24.4 and 0.937–0.956, respectively). Additionally, a Structure analysis suggested that all samples compose a single genetic cluster. These data suggest that natural populations of D. antillarum are genetically similar throughout the Florida Keys, from Dry Tortugas National Park through Biscayne National Park, and that captive-bred individuals could be used for reintroduction as part of a plan to re-establish healthy urchin populations throughout the Florida Keys.