LA DISTRIBUCION BATIMETRICA DE LOS FORAMINIFEROS BENTONICOS

Abstract

The bathymetric distribution of benthic foraminifera depends on two principal factors (and all ecological parameters related to them): (a) depth and (b) water-rnass. In the inner shelf depth plays the main role. In the outer shelf, and in the case of isobathyal species also in the deeper zones, the predominant factor is still the depth, but water mass can play a rather important role. In the case of heterobathyal species of great depth the qualitative characteristic of the assemblage depends on the depth; however, the abundance of individual species depends on water mass. The use of generic names only to characterize in detail a bathymetric zone by benthic foraminifera is insufficient because even such a typical near-shore genus as Elphidium has species which live at great depths. The analysis of published data as well as our own studies reveal that the following foraminifera should be considered as typical inhabitants of solely the bathyal zone (rnainly middle bathyal; 500-2500 m): Ammodiscus tenuis, Anomalina globulosa, Bolivina pusilla, Bulimina rostrata, Cibicides bradyi, C. kullenbergi, C. robertsonianus, C. rugosus, Cystammina pauciloculata, Eponides polius, E. tumidulus, Favocassidulina favus, Hormosina globulifera, Oolina longispina, Osangularia culter, Quinqueloculina venusta, Trochammina globigeriniformis, Uvigerina ampullacea, U. hispida, U. peregrina dirupta, U. senticosa, Virgulina complanata.