HABITAT HETEROGENITY ON TROPICAL ROCKY SHORES: A SEAWEED STUDY IN SOUTHERN BRAZIL

The main concepts in coastal community ecology have been proposed to explain relatively plain substrate, specially at temperate zones. We show that, on a irregular tropical substratum (a complex system of quarry stones with diverse shapes and sizes), the classical community zonation scheme is only applicable if we simplify the tridimensional substrate arrangement to a single dimensioned universe: the topographic level. Thus, the continuous spatial distribution implicited in “zones” notions is nonexistent. Our study was conducted on a rocky shore at Ubatuba (São Paulo State, Brazil) during one year. Percentual coverage was estimated using the quadrat method located by random coordinates. The topographic level was determined for each sampling element. Analysis of spatial splitting revealed large‐scale stratification of the shore into dominiums related to topographical level: 1) Upper Dominium (represented by Chthamalus sp. and Tetraclita spalactifera); 2) Transition Level (composed of Gymnogongrus griffithsiae, Gelidium aff. pusillum and often Centroceras clavulatum);. and 3) Lower Dominium (mainly Sargassum vulgare and occasionally Padina gymnospora, Dictyopteris delicatula and Grateloupia doryphora). These dominiums cannot be recognized as “bands” or continuous “zones” in a landscape view of the community. Otherwise, these bands could be observed on a small scale on each large quarry stone.