VERTICAL DISTRIBUTION PATTERNS OF LIVING (STAINED) BENTHIC FORAMINIFERA FROM THE ALEUTIAN MARGIN

Vertical distribution patterns of living (rose Bengal-stained) benthic foraminifera (>150µm) were analyzed within tube core sediments taken by the ROV JASON II from an unexplored region of the Aleutian margin near Unimak Island. At a bathyal site (1988m water depth) the agglutinated assemblage had a density maximum at the 0-1cm interval, while calcareous standing stocks of foraminifera had an infaunal maximum.  Infaunal patterns observed at this site are similar to those observed in similar water depths elsewhere.  Dominant infanual taxa include: Globobulimina pacifica, Nonionella stella, Nonionella globosa, Elphidium sp., and Chilostomella oolina.  At this site, deep infaunal species G. pacifica, reaches unusually high densities (about 90/50cc) between 3 and 5cm.  High densities of infaunal taxa on the Aleutian margin may result from increased availability of labile organic matter brought in by turbidite sedimentation.  Results from this study reveal clues about the factors which control the distribution of foraminifera within seafloor sediments, and provide modern analog data for interpretations of the paleoceanographic record.