Kelley, C. A.. University of Missouri-Columbia, geolck@showme.missouri.edu
Martens, C. A.. University of North Carolina, cmartens@marine.unc.edu
Coffin, R. B.. Naval Research Laboratory, rcoffin@ccf.nrl.navy.mil
Cifuentes, L. A.. Texas A&M University, cifuente@nitro.tamu.edu

 
ALLOCHTHONOUS VS. AUTOCHTHONOUS BACTERIAL CARBON SOURCES: A COMPARISON BETWEEN THE NORTHERN GULF OF MEXICO AND A COASTAL MARINE BASIN (CAPE LOOKOUT BIGHT, NC)
 
Depleted bacterial stable carbon isotopes have been observed in the northern Gulf of Mexico. The oxidation of methane has been implicated. Because of its environmental setting and its proximity to the Mississippi River, terrestrial organics and petroleum hydrocarbons profoundly affect the POC pool and the microbial cycling of carbon here. A comparison of this region to an organic-rich coastal marine basin in which in-situ processes control carbon cycling has revealed significant differences. Water samples were obtained at Cape Lookout Bight (CLB), NC in August 1998. The <0.8 um size particles were predominantly bacterial in nature, having a C/N ratio of <5. In contrast, Gulf of Mexico (GOM) samples, collected in July 1998, exhibited a C/N ratio in the <0.8 um size fraction of >45, indicative of a terrestrial source. Bacterial growth and efficiencies were calculated for both sites based on particulate C and N changes over time in the <0.8 um fraction. Although bacterial growth at CLB (0.012 umol C/L hr) was slower than at the GOM site (0.034 umol C/L hr), CLB bacteria were more efficient in their growth, 52% versus 13% at the GOM site. Little, if any, methane was oxidized at either site at this time.
 
Day: Tuesday, Feb. 2
Time: 11:45 - 12:00pm
Location: Eldorado Hotel
 
Code: CS56TU1145E