Abstract

The composition of recent benthic foraminifera was analyzed in eight sedimentological interfase samples collected with a box core of 0,16 m2 surface in Mejillones del Sur bay (23° S) at depths of 56 to 138 m. The study area is characterized by a large relative abundance of Bolivina seminuda Cushman and the presence of Nonionella stella Cushman & Moyer and Bolivina costata Orbigny. The registered diversity (H) is low and varies between 0,8 and 2,4. The deepest station near Punta Angamos, presents the highest index and is the only one with Cancris auriculus (Fichtel & Moll) and Valvulineria inflata (Orbigny). The faunistic density of stations located in the center and external zones of this bay showed the highest values (average= 2600 ind/g), with most of the material representated by Bolivina seminuda. The results showed that the benthic foraminiferal distribution is directly related with bottom-water oxygen content. B. seminuda is adapted notably to microxic conditions (0.01 ml 1-1). Buliminella elegantissima (Orbigny) is found in more oxygenated areas (0,5 ml 1-1), while B. costata and N. stella were found in both environments.