Benthic foraminiferal population fluctuations related to anoxia: Santa Barbara Basin |
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| Authors: | Joan M Bernhard Clare E Reimers |
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| Institution: | (1) Scripps Institution of Oceanography, University of California, 92093-0215 San Diego, La Jolla, CA, USA;(2) Present address: Wadsworth Center for Laboratories and Research, New York State Department of Health, P.O. Box 509, 12201-0509 Albany, N.Y., USA |
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| Abstract: | The pore-water geochemistry and benthic foraminiferal assemblages of sediments from two slope sites and within the central portion of the Santa Barbara Basin were characterized between February 1988 and July 1989. The highest foraminiferal numerical densities (1197 cm–3 as determined by an ATP assay) occurred at a slope site in June 1988 (550 m) in partially laminated sediments. In continuously laminated sediments from the central basin, foraminifera were found living (as determined by ATP assay) in October 1988 to depths of 4 cm, and specimens prepared for transmission electron microscopy were found with intact organelles to 3 cm, indicating their inhabitation of anoxic pore waters. Ultrastructural data from Nonionella stella is consistent with the hypothesis that this species can survive by anaerobic respiration. However, the benthic foraminifera appear unable to survive prolonged anoxia. The benthic foraminiferal population was completely dead in July 1989 when bottom water O2 was undetectable. |
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| Keywords: | anoxia ATP foraminifera geochemistry organic-rich sediments ultrastructure |
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