Connectivity of Queen conch, Strombus gigas, populations from Mexico

Abstract

Despite active conservation measures, slow recovery of Queen conch (Strombus gigas) is a growing concern in the Caribbean. Conventional expectations presume that S. gigas populations are largely connected, but we present results of veliger larval drift and survival from the Yucatan peninsula that suggest otherwise. Spatial patterns of observed and simulated larval stages during the reproductive season revealed segregation of the Mexican populations, with high levels of larval retention on Campeche Bank contrasted to variable larval transport along the Mexican Caribbean coast into the Yucatan Current, and eventually into the Loop Current. Consequently, the probability that S. gigas larvae originating from the Mexican Caribbean settle to Alacranes Reef is null. In addition, the Alacranes S. gigas population is not source to Florida, while a small fraction of larvae produced north of the Mexican Caribbean coast periodically reaches the Florida Keys (ca. 1-12%) and Cuba (0.1-4%), while very few individuals reach the NW Bahamas (0-0.5%). Although this long-distance dispersal may not be sufficient to replenish the downstream populations, gene flow could prevent differentiation of the Florida Keys and Mexican Caribbean Queen conch populations. This study constitutes a first step in understanding Queen conch metapopulation structure and calls for more local actions for the recovery of Mexican populations.