Cotner, J. B.. Department of Ecology, Evolution and Behavior, University of Minnesota, cotne002@tc.umn.edu
Johengen, T. B.. NOAA Great Lakes Environmental Research Laboratory, johengen@glerl.noaa.gov
Biddanda, B. A. Department of Ecology, Evolution and Behavior, University of Minnesota, bidda001@tc.umn.edu

 
RAPID BACTERIAL PRODUCTION IN EXTREMELY COLD WATERS IS STIMULATED BY BENTHIC-PELAGIC EXCHANGES
 
An important paradigm in microbial ecology is that secondary productivity is constrained by temperature in cold water systems. We examined bacterial production and biomass during a recurrent sediment resuspension event in Lake Michigan. We found that, in spite of extremely cold temperatures (<2 degrees C) and low primary production, bacterial productivity in the plume was comparable to rates measured in the summer. Productivity during peak plume development was commonly greater than 20 and as high as 50 ug C/L/d. For comparison, summer values in southern Lake Michigan average ca. 30 ug C/L/d. There was a strong correlation between total suspended material and bacterial production (r^2=0.70) during the resuspension event suggesting that particulate matter associated with the plume may provide nutrients that stimulate production. Survey data did not indicate increased DOC concentrations in the plume but P concentrations were elevated where the plume was most developed. These observations suggest that winter bacterial production can represent an important carbon and nutrient flux in Lake Michigan and may be temporally de-coupled from primary productivity.
 
Day: Thursday, Feb. 4
Time: 03:45 - 04:00pm
Location: Eldorado Hotel
 
Code: SS52TH0345E