Spatial distribution of the most abundant sea urchin populations on the southeast coast of Sao Paulo (Brazil)

The spatial variability of Echinometra lucunter; Lytechinus variegatus and Arbacia lixula was studied in relation to four spatial scales (10(5), 10(4) , 10(3) and 10(2) m) and two depths (0-3 and 3-8 m), along 100 km of the Sa o Paulo coastline (August to October 1996). Echinometra lucunter was the mo st abundant species, with preference for shallow substrates subject to wave action. An abundance gradient was identified, increasing from southwest to northeast. Arbacia lixula showed the same pattern of spatial variation, bu t was more abundant in the deeper areas. Both species showed significant di fferences on a spatial scale of hundreds of meters, and E. lucunter also on a scale of kilometers. Lytechinus variegatus presented a patchy distributi on, being more abundant at certain sites. Variations in the water quality a nd natural heterogeneity of the habitat may explain the spatial distributio n of these populations.