The foraminifera from the Bazaruto Archipelago (Mozambique)

The Bazaruto Archipelago in the western Indian Ocean is home to a diverse reef biota and a notable tourist attraction along the coast of Mozambique. Analyses of shallow-water reefal and lagoonal sediments from Bazaruto Island reveal two diverse assemblages of benthic foraminifera. The assemblages occupy three major environments and sedimentary regimes and are indicative of reef, channel and lagoon facies. Species richness, Fisher a analyses, assemblage composition, and percentage abundances of larger-symbiont-bearing foraminifera are mirrored in the cluster analyses. In general, the reef environments on the eastern side of Bazaruto Island harbor more species, higher percentages of larger symbiont-bearing, agglutinated, and hyaline-perforate foraminifera. In contrast, the lagoon facies is characterized by high numbers of smaller miliolid foraminifera. The current-dominated open ocean channel environments south of Bazaruto Island are subject to extreme winnowing and house low-diverse assemblages, reflecting areas of wave-transport accumulation and redistribution. Among the larger benthic foraminifera from Bazaruto, species of the genus Amphistegina are prominent producers of calcium carbonate. They contribute substantially to the carbonate budget and provide support to the framework and stability of reefal structures. Because of their abundance and role as prominent carbonate producers, amphisteginid foraminifera can be considered ecosystem engineers. The distinct differences between reef and lagoon faunal assemblages imply low horizontal transport rates. Thus, the autochthonous benthic assemblages may preserve the original community structure and sufficient environmental information to be useful indicators for paleoecological studies.