Distribution and diversity of echinoderms (Asteroidea, Echinoidea, Holothuroidea) in the islands of the Gulf of Chiriqui, Panama

Abstract

Studies on echinoderms along the Panamanian Pacific coast have focused mainly on evolutionary and molecular analyses, however little ecological research has been done and mainly only on 2 species: Diadema mexicanum and Acanthaster planci. Herein, we describe for the first time the diversity (based on Margalef, Shannon and Pielou indices), distribution and density of echinoderms for some islands of the Gulf of Chiriqui, implementing a standard regional methodology used for the Eastern Tropical Pacific Conservation Seascape. Fifty-three reef sites were surveyed, of which 17 echinoderm species were found: 6 asteroids, 6 echinoids and 5 holothuroids. The average species richness, Shannon diversity, and Pielou's evenness indices were 0.43 +/- 0.04, 0.187 +/- 0.020, and 0.421 +/- 0.035 respectively. On average there were 3 species and 176 individuals per site. Three echinoid species were the most abundant: D. mexicanum, Eucidaris thoaursii and Echinometra vanbrunti, with 7909, 771 and 569 individuals respectively. Despite the high abundance observed, their impact on the reefs as well as other corallivores species (e. g., A. planci) is low, and for the moment they are not considered a threat to the reefs. Reef zones with greater richness and diversity of echinoderm species are associated with sites showing higher coral diversity and moderate to high live coral cover. We suggest a continuous assessment of the populations possibly damaging these ecosystems, as well those species that may be under illegal extraction.