Aquatic Sciences Meeting, Albuquerque 2001

PC09 River and Margin Biogeochemistry

Date: Wednesday, February 14, 2001

Location: Southwest Hall

Boyd, T, J, US Naval Research Laboratory, Washington, USA, tboyd@ccsalpha3.nrl.navy.mil

Coffin, R, B, US Naval Research Laboratory, Washington, USA, rcoffin@ccf.nrl.navy.mil

Osburn, C, L, US Naval Research Laboratory, Washington, USA, cosburn@ccs.nrl.navy.mil

TERRESTRIAL DOM MAY NOT BE REFRACTORY TO MARINE BACTERIA

The amount of terrestrially-derived dissolved organic matter (T-DOM) flowing into coastal systems could constitue the entire oceanic DOM pool within 2000 years given no degradation. However, there is little terrestrial character to marine DOM. Little is understood about the mechanisms of T-DOM degradation in these environments. We aim to determine the biological and photochemical lability of T-DOM when it is presented as a “new” carbon source to allochthounous bacterioplankton. On three cruises (Nov99, Mar00, and Sep00) marine, estuarine and freshwater bacteria and colored DOM (>1kD) were isolated via 0.22 micron filtration and tangential flow ultrafiltration, respectively. Incubations were set up using each type of bacterioplankton and DOM and monitored for several weeks. Measurements are being made of heterotophic bacterial production, DOM concentration, bacterial abundance, UV absorbance, fluorescence, bulk respiration, and stable carbon isotope ratios. Preliminary results suggest a relative increase in the utilization of allochthonous DOM. Marine bacteria preferentially degrade freshwater DOM (36% remaining after 7 days vs. 51% remaining marine DOM). We will also present calculations of the biogeochemical significance of allochthonous DOM biodegradation.

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Aquatic Sciences Meeting, Albuquerque 2001

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