Sex-ratio and occurrence of hermaphroditism in populations of Diadema antillarum (Echinoidea: Diadematidae) at two contrasting habitats in Tenerife (Canary Islands)

Abstract

Gonad histological examination of the Canary Islands populations of the echinoid Diadema antillarum was conducted in two types of habitats («barrens», i.e. habitats characterised by high visible crustose coralline algal cover typical of urchin-barren grounds, and by absence of macroalgae; and «fringe», i.e. habitats characterised by high macroalgal biomass and few D.antillarum). Sex ratio did not differ significantly from 1:1 at either habitat. One hermaphrodite echinoid was found at the barren habitat out of the total of 572 echinoids examined. Diadema antillarum did not show labile gonochorist and sex determining mechanisms influenced by habitat.