3:15 AMMONIFICATION, NITRIFICATION, AND DENITRIFICATION IN SHINGOBEE RIVER SEDIMENTS, MINNESOTA: THEIR COMBINED AFFECT ON SEASONAL SURFACE WATER CHEMISTRY.
J.H. Duff¹, F.J. Triska¹, R.J. Avanzino¹, A.P. Jackman², and R.W. Sheibley III². ¹U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, ²University of California, Department of Chemical Engineering, Davis, CA 95616

3:30 PHOSPHOROUS UPTAKE BY BENTHIC ALGAL COMMUNITIES IN ANTARCTIC STREAMS.
M.N. Gooseff and D.M. McKnight. Institute of Arctic and Alpine Research, University of Colorado, 1560 30th St., Boulder, Colorado, 80309-0450

3:45 COLMATION CONSEQUENCES: EFFECTS OF SEDIMENTATION ON THE HYPORHEIC ZONE.
M.R. Scarsbrook and J. Halliday. National Institute of Water & Atmospheric Research, Hamilton, New Zealand

4:00 EXPERIMENTAL MANIPULATIONS OF FOOD AND NUTRIENTS IN RIVER SEDIMENTS AND THE EFFECTS OF SEDIMENT DEPTH AND A SCOURING SPATE ON HYPORHEIC COMMUNITY METABOLISM.
G.P. Burrell. Department of Zoology, University of Canterbury, Christchurch, New Zealand

4:15 BENTHIC MACROINVERTEBRATE RESPONSE TO GROUNDWATER-SURFACE WATER INTERACTION ON ALLUVIAL FLOODPLAINS OF TWO NORTHWEST MONTANA RIVERS.
D.M. Pepin and F.R. Hauer. Flathead Lake Biological Station, The University of Montana, Polson, Montana USA 59860-9659

4:30 OCCURRENCE OF LARGE-BODIED HYPORHEOS IN ANOTHER LARGE GRAVEL-BED RIVER.
E.B. Snyder and J.A. Stanford. Flathead Lake Biological Station, The University of Montana, Polson, MT 59860-9659