Woods Hole Oceanographic Institution

Joan M Bernhard

» Effects of carbon dioxide disposal on deep-sea foraminifers

» Culturing studies of environmental controls on benthic foraminiferal shell chemistry

» Understanding stable isotopic disequilibrium in benthic foraminifera from hydrocarbon seeps

» Foraminifera and other eukaryotes from sulfidic marine environments

Enlarge image
Laser Scanning Confocal image (z-stack) of FLEC core showing an anaerobic symbiont-bearing ciliate (magenta arrow) among other microbial eukaryotes and prokaryotes. White arrows point to flagellates; magenta arrows point to oral area of ciliate. See Bernhard et al. (2003) Limnology & Oceanography for more details of the method and other observations. (J.M. Bernhard)

Foraminifera and other eukaryotes from sulfidic marine environments

Virgina Edgcomb (WHOI); Samuel Bowser (Wadsworth Center, NY State Department of Health); Katrina Edwards (WHOI MC&G)

One of my long standing interests involves eukaryotes inhabiting oxygen-depleted and anoxic sediments, with or without sulfide enrichment. Over the past ~10 years, colleagues and I have studied the fauna in Santa Barbara Basin (Bernhard, Buck, Farmer & Bowser 2000 Nature; Grzymski et al. 2002 L&O; Bernhard, Visscher & Bowser 2003 Limnology & Oceanography), Cariaco Basin (Bernhard 2003 Science), Norwegian Fjords (Bernhard & Alve 1996 Marine Micropaleontol), cold seeps (Bernhard, Buck & Barry 2001 Deep-Sea Research I; Robinson et al. 2004 Marine Ecology), and the Black Sea (JMB unpublished). Results indicate that foraminifera commonly dominate these sediments and the dominant eukaryotes typically have putative symbionts. In addition, life position analysis (FLEC, see Bernhard et al., 2003 L&O) indicates complex associations of physiologically diverse microbial communities within a single laminae, suggesting heterogeneous pore-water habitat mosaics exist on the nanoliter scale. Thus, improved nanoscale pore-water chemistry monitoring is needed as well as in situ observations of microbial activity to understand the formation of these unparalleled paleoceanographic records. These studies have been funded by NSF Biological Oceanography, NSF Marine Geology & Geophysics, NSF Microbial Observatories, and NASA Exobiology. Presently, Katrina Edwards and I are modifying the FLEC method to allow simultaneous imaging of specific groups of microbes (labeled with FISH); this pilot study is being funded by WHOI's Ocean Life Institute and NSF. Ginny Edgcomb and I are funded by NSF MIP to identify the symbionts of selected ciliates and flagellates of Santa Barbara Basin sediments. Check back periodically for updates on our progress.

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