Published online by Cambridge University Press: 10 September 2014
The sea urchin Diadema africanum is considered a keyherbivore in sublittoral ecosystems of the Canary Islands. Spatial andtemporal variability in population structure was carried out at GranCanaria. We performed a morphometric and population density analysis during2005, 2006 and 2007 at four sites in zones of Gran Canaria. The studyconsidered a vertical gradient (5, 10 and 20 m depth) during both seasons,the cold season (February and March) and the warm season (October andNovember). The sea urchin D. africanum in Gran Canariaexhibited an overall density of 7.59 ± 2.92 urchin m−2. A two-wayANOVA evidenced spatial differences in mean abundance of the species, whileseasonality was not relevant. The vertical analysis of the abundance of D. africanum showed differences, the smaller sizesappeared at greater depths. The Aristotle's lantern width decreased in avertical gradient, being remarkable between 10 and 20 m. Findings ofuniformity in size over time, a stable range of high densities and the lackof a relationship between the size of the sea urchins and the season revealsthat the density–size strategy displayed by D. africanumwhich explains in turns the high stability of the urchin barrens, which,once developed, remain as areas of permanent desertification in subtidaldepths throughout the Canary Archipelago.