Scranton, M. I. SUNY at Stony Brook, mscranton@notes.cc.sunysb.edu
Taylor, G. I. SUNY at Stony Brook, gtaylor@notes.cc.sunysb.edu
Bohrer, R. Univ. of So. Florida, rbohrer@marine.usf.edu
Astor, Y. Fundacion La Salle, cariaco@telcel.net.ve
Ho, T. SUNY at Stony Brook, hty@pro.msrc.sunysb.edu

 
BIOGEOCHEMICAL EFFECTS OF RECENT INTRUSIONS INTO THE ANOXIC ZONE OF THE CARIACO BASIN
 
Recent intrusions of oxygenated water into the mid-depth and bottom waters of the Cariaco Basin have had marked effects on the cycling of organic carbon in that system. Most notably, in 1997 and 1998 a series of oxygen-rich intrusions depressed the depth of the oxic/anoxic interface from around 250 m to about 330-350 m. For several months, in a zone almost 100 m thick, both oxygen and sulfide concentrations were below our detection limit. More recently, however, it appears that oxygen is detectable until just above the appearance of sulfide. A variety of measures of bacterial activity (leucine incorporation, acetate uptake, chemoautotrophic activity) suggest that the biological communities readily responded to the change in the interface depth. In addition to the intrusions centered on the interface, we have also observed the effects of an earthquake (Richter 6.8) which took place 150 km to the southeast of our station. The earthquake seems to have resulted in intrusion of shelf water (high temperature and salinity) into the bottom of the Cariaco Basin. Sulfide concentrations in the deep waters of the Cariaco were significantly lower after the earthquake, although the effect on other geochemical constituents is still being evaluated.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS38WE1353S