SS2.05 Phylogenetic and Physiologic Successions in Aquatic Bacterial Communities
Date: Monday, June 10, 2002
Time: 11:15:00 AM
Location: Carson C
 
CrumpBC, The Ecosystems Center, Marine Biological Lab., Woods Hole, USA, bcrump@mbl.edu
Bahr, M, , The Ecosystems Center, Marine Biological Lab., Woods Hole, USA, mbahr@mbl.edu
Kling, G, W, U. of Michigan, Ann Arbor, USA, gwk@umich.edu
Hobbie, J, E, The Ecosystems Center, Marine Biological Lab., Woods Hole, USA, jhobbie@mbl.edu
 
SHIFTS IN THE MICROBIAL COMMUNITY COMPOSITION OF AN ARCTIC LAKE IN RESPONSE TO SEASONAL SHIFTS IN ORGANIC MATTER SUPPLY
image
Planktonic bacterial production below the ice of Toolik Lake (Alaska, USA), increases rapidly with the Spring thaw as fresh dissolved organic matter (DOM) and nutrients are washed off the tundra surface. Subsequently, as terrestrial inputs decline and lake ice disappears, phytoplankton production is thought to maintain the microbial community. The bioavailability of DOM (microcosms) and bacterial production rate (14C-leucine) in the main inlet stream in 1996 were relatively high during the period of highest stream flow, decreased progressively for about 3 weeks, and then rose again as a result of increased primary production upstream. In 2000, bacterial production followed a similar pattern in both the inlet stream and the surface waters of Toolik Lake. Two shifts in the composition of Toolik Lake bacterial communities (DGGE patterns) were detected corresponding to: 1. peak bacterial production associated with high terrestrial DOC flux, and 2. peak chlorophyll concentration after ice out. DNA sequencing demonstrated that bacteria represented in DGGE patterns are members of globally-distributed freshwater bacterial clusters, and that shifts in the bacterial community occurred at both the genus and the species level.