Wednesday, May 28, 2008 - 10:45 AM
403

Effect of arctic lakes on stream macroinvertebrate communities (North Slope, Alaska)

Heidi M. Rantala and Alexander D. Huryn. Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, AL 35487-0206

Although lakes are known to be biological hotspots in Arctic lake-stream networks, little is known about their impact on their connecting streams in tundra systems.  We studied the longitudinal influence of three Arctic lakes on their connecting streams.  We sampled macroinvertebrate communities in inlet streams and at 0m, 100m and 300m in outlet streams.  Total macroinvertebrate biomass was lower in inlets than outlets and decreased with increasing distance downstream from lakes.  The mayfly Serratella, the snail Valvata and the shredding crane fly Tipula contributed less to abundance and biomass of inlet than outlet communities (p<0.05).  Outlet stream communities were also significantly different between 0m and 300m, with the abundance and biomass of the aforementioned taxa decreasing with distance downstream.  Biomass of filter-feeding invertebrates (primarily the midge Rheotanytarsus) also decreased longitudinally below lake outlets.  These results suggest that the structure and function of Arctic stream communities are controlled significantly by the attributes of associated lakes.  Since the abundance and distribution of lakes on formerly glaciated terrains are a function of time since glacial recession, we predict that landscape-level patterns of stream macroinvertebrate community attributes in regions affected by continental glaciers will be determined to a significant degree by relative terrain age.


Web Page: stream-lake network

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