Manganelli, M. Scripps Institution of Oceanography, mmanganelli@ucsd.edu
Bidle, K. Scripps Institution of Oceanography, kbidle@ucsd.edu
Azam, F. Scripps Institution of Oceanography, fazam@ucsd.edu

 
TEMPERATURE DEPENDENCE OF POC MINERALIZATION BY MARINE BACTERIAL ASSEMBLAGES.
 
Since marine bacteria interact with living diatoms and have high enzymatic activity on particles they play active roles in the transformation of particulate organic carbon (POC). During episodic phytoplankton blooms, bacterial processes are important for carbon flux through the microbial loop and for nutrient regeneration. Colonized particles often sink and experience temperature changes which could influence the rates of bacterial solubilization and utilization of POC. We tested the effect of three temperatures (33, 15 and 5 C) on the utilization of fresh diatom detritus by a bacterial assemblage collected off Scripps pier. Uniformly 14C labeled Thalassiosira weissflogii was used to follow 14C fate. No PO14C consumption or degradation was measured for detritus incubating either under abiotic condtions (all temperatures) or with bacteria at 5 C. For bacterial incubations at 33 and 15 C 70 and 40% of POC, respectively, had been utilized after 4 days and this was consistent with increases in CO2 and bacterial biomass. No significant variations in DOC were observed. Higher specific growth rates and carbon production at 33 C appeared in the first 24 hours. The implications of these results will be discussed with regard to the role of bacteria on sinking particle in stratified systems.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS38WE1111S