TY - JOUR AU - Herrero-Pérezrul, María Dinorah AU - Ramírez-Ortíz, Georgina AU - Rosales-Estrada, Mauricio AU - Reyes-Bonilla, Héctor PY - 2015/06/01 Y2 - 2024/03/28 TI - Population density and spatial distribution of sea urchins (Echinodermata: Echinoidea) at Socorro island, Revillagigedo archipelago, Mexico. JF - Revista de Biología Tropical JA - Rev. Biol. Trop. VL - 63 IS - S2 SE - Articles DO - 10.15517/rbt.v63i2.23156 UR - https://revistas.ucr.ac.cr/index.php/rbt/article/view/23156 SP - 221–232 AB - <p>The studies on echinoderms of the Mexican Pacific have focused on taxonomy and biogeography, and there are limited data on their ecology. We used transect to study <em>Diadema mexicanum, Echinometra mathaei oblonga, Eucidaris thouarsii </em>and<em> Tripneustes depressus</em> at three bays in Socorro Island, Revillagigedo Archipelago, Mexico (1989 and 1990). The most abundant species in the island was <em>E. mathaei oblonga</em> (3.96 <span>+</span> 0.83 ind m<sup>-2</sup>; average and standard error), followed by <em>D. mexicanum</em> (2.13 <span>+</span> 0.59 ind m<sup>-2</sup>), <em>T. depressus </em>and<em> E. thouarsii</em> (between 0.50 and 0.11 ind m<sup>-2</sup>, respectively). Binners Bay had the highest density with 15.98 <span>+</span> 0.43 ind m<sup>-2</sup>, mostly due to the high incidence of <em>E. mathaei oblonga</em> at the site. Seasonally, <em>T. depressus</em> and <em>E. thouarsii</em> did not significantly varied its abundance during the year, while <em>D. mexicanum</em> was more abundant in winter-spring, and <em>E. mathaei oblonga</em> in the fall. Two species (<em>D. mexicanum</em> and <em>E. mathaei oblonga</em>) had an aggregated distribution along the year and in the three study locations, but the other two echinoids followed a random distribution. This may be a defense against the abundant predatory fishes. In contrast, the species that do not aggregate inhabit in refuges during the day (<em>E. thouarsii</em>), or their shape and size makes them difficult to capture by fishes (<em>T. depressus</em>).</p><div> </div> ER -