PARENT SESSION
Poster Session #23: Fish, Lakes, Streams, and Wetlands.
Wednesday, August 8, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
109
Physical, chemical, and biological characteristics of barrenland tundra streams of the Northwest Territories.
Jones, Nicholas1, Scrimgeour, Garry2, Tonn, William1, 1 2
ABSTRACT- During 1998-2000, we surveyed 20 tundra streams in a 4000 km2 area on the barrenlands of east-central NWT, Canada, a largely unstudied region now hosting one existing and several projected diamond mines. Streams typically connect chains of lakes, but because of limited rainfall, flows decline steadily following snowmelt. These lake-outlet streams are often braided into several channels and meander little over weak hydraulic gradients. Substrates consist mainly of large boulders and organic detritus. Streamwater is moderately acidic and low in alkalinity and nutrients, similar to streams further south on the Canadian Shield. Streams and small rivers freeze solid during winter, concentrating active hydrological and biological processes to between late-May and September. Aquatic macrophytes grow well in slower sections of stream and filamentous algae become abundant in the low flows of late summer. Riparian vegetation is limited to sedges, grasses, dwarf birch, and willow, which contribute fine woody debris and particulate organic matter that are utilized by collector-gatherer benthic invertebrates. Drift, often dominated by microcrustaceans of lake origin, shows little diel variation but is subject to periodic disturbance from caribou migration. Fish communities are impoverished, but many streams serve as spawning, nursery, and juvenile habitat for lake-dwelling Arctic grayling populations. These surveys will provide a benchmark for the effectiveness of restorative and enhancement measures for fish habitat affected by development activities in this unique area of the Canadian north.
KEY WORDS: Arctic grayling, benthic invertebrates, Northwest Territories, tundra streams