28 Limnogeology and Paleontology (Posters)
Friday, 25 April 2014
1:30 PM - 6:00 PM
Lancaster Ballroom
THE ECOLOGY OF BENTHIC FORAMINIFERA LIVING IN AN OXYGEN MINIMUM ZONE ON THE EASTERN PACIFIC MARGIN
Paper number: 28-2
Program: Technical Sessions
Time: 1:30 PM – 6:00 PM
Authors
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Anthony RathburnIndiana State University, Terre Haute, IN
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Brendan D. PaddackIndiana State University, Terre Haute, IN
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Ashley BurkettIndiana State University, Terre Haute, IN
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Wiebke ZiebisUniv of Southern California, Los Angeles, CA
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Elena M. PerezNatural History Museum, London, N/A
Abstract
In an effort to evaluate benthic foraminiferal abundances and assemblages within an oxygen minimum zone, multicore samples were collected along a depth transect (360-3000m) within the Southern California Bight. In this study area, bottom water oxygen values varied from 0.38 ml/L to 3.63 ml/L, temperatures ranged from 2.9oC-7.1oC, and mean grain size ranged from 23.9-105.7 µm. Living (Rose Bengal stained) specimens of the >150µm fraction were examined from 0-2cm and the 63-150µm fraction were examined from the surface sediments (0-1cm) of multicore tubes. Abundant taxa in the >150µm fraction included Uvigerina spp., Cassidulina spp., Hoeglundina elegans., Nonionella sp., Hanzawaia nipponica, and Cibicidoides wuellerstorfi. Vertical distributions of Cassidulina sp., H. nipponica and H. elegans in the >150µm fraction indicate epifaunal microhabitat preference at all depths from 690m to 1050m, with greatest abundances at the 360 m site. Globobulimina spp., Uvigerina spp., and Chilostomella oolina in the >150µmportion, were relatively abundant in surface sediments. Standing stock values of the >150µm assemblage (primarily calcareous taxa) ranged from 55 individuals/50cm2 at 1050m to 831 individuals/50cm2. Comparisons of the >150µm fraction assemblages with those of the 63-150µm fraction will yield additional insight into the ecology and distribution patterns of dominant species, and provide modern analogs to assess fossil assemblages.