LIVING (STAINED) BENTHIC FORAMINIFERAL ASSEMBLAGES ALONG A DEPTH TRANSECT OFF THE COAST OF SOUTHERN CALIFORNIA

Living (Rose Bengal stained) foraminifera (greater than 150 microns) of multicorer surface sediments (0-1 cm) collected off the coast of southern California along a depth transect (360-3000 meters) revealed differences in assemblages between sites. In order to examine foraminifera from habitats not typically sampled on productive margins, sites with coarser-grain sediments were targeted in the oxygen minimum zone. Bottom water oxygen values at these sites ranged from 0.63 ml/L at 360 meters to values of 0.47 and 0.81 ml/L at 1000 meters to 1.5 ml/L at 1500 meters. Uvigerina spp. were the most common and most abundant calcareous taxa occurring at all but one of the sites, and Bolivina spp. were found at a majority of the sites. The epifaunal species, Planulina wuellerstorfi, typically associated with higher bottom water O₂ values, was one of the dominant taxa at 1000 meters. Hoeglundina elegans was also found at most of the sites. Other common species included Cassidulina spp., Pyrgo sp., and Rutherfordoides rotundata. These results indicate that, along a depth transect across what is typically considered an oxygen minimum zone, habitat heterogeneity may influence foraminiferal assemblages.