SS3.01 Landscape Control of High Latitude Lake and River Ecosystems
Date: Thursday, June 13, 2002
Time: 2:30:00 PM
Location: Carson A
MacIntyre, S, , Marine Science Institute, UCSB, Santa Barbara, CA, USA,
KlingG, Dept. EEB, University of Michigan, Ann Arbor, MI, USA,
Kipphut, G, W, Geological Sci., Murray State U., KY, USA,
Hobbie, J, , Marine Biological Laboratories, Woods Hole, MA, USA,
Sickman, J, O, Dept. Water Resources, Sacramento, CA, USA,
Goldthwait, S, , Dept. of EEMB, Univ. of Calif., Santa Barbara, CA, USA,
We determined the influence of stream inflows on lake metabolism as measured by bacterial and primary production. The impact of spring snowmelt versus mid-summer storm events was compared in Toolik Lake, arctic Alaska. In spring, snowmelt runoff was confined to a thin layer beneath the lake's ice cover and induced basin-wide increases in bacterial productivity of ~10 fold within 10 days. Increases in primary productivity lagged by ~5 days, and reached a 7-fold peak along the main flow path under the ice. In mid-summer, intense mixing from a storm inflow reduced the density stratification and dispersed the chlorophyll maximum in the two basins nearest the inlet. Initially, primary productivity in surface waters increased 5 fold due to vertical mixing and advection over the lake of light-limited, nutrient-replete phytoplankton from these basins. Subsequent stimulation of productivity was likely due to nutrients from mineralization of DOM that entered the lake as a subsurface intrusion. Because snowmelt occurs every year and storm inflows of this magnitude occur every other year, such physical and chemical impacts on productivity are important to annual lake metabolism.