PARENT SESSION
Oral Session #65: Aquatic Ecology: Stream and Lake.
Presiding: C. Osenberg
Wednesday, August 7. 1:00 PM to 4:45 PM. Coconino Meeting Room, TCC.
Discontinuity in stream ecosystems: the influence of lakes and small dams.
Pollard, Amina*,1, Magnuson, John1, 1 University of Wisconsin- Madison, Madison, Wisconsin
ABSTRACT- Fragmentation owing to the damming of rivers and streams can alter the distribution of benthic invertebrates, primarily because dams disrupt resource gradients. Although many studies have focused on the effects of large dams on invertebrate distribution, natural lakes and small impoundment (<100 ha) may also cause changes in flow regime. We ask whether the distribution of benthic invertebrates in a stream network is influenced by lentic disruptions of the stream caused by natural lakes and small dams. And if so, does the effect depend on the type of lentic disruption? Benthic invertebrate samples were taken along transects in inlet and outlet streams of natural lakes and impoundment in northern Wisconsin. We evaluate invertebrate community characteristics (abundance, diversity and functional groups) to examine how the distribution is affected. Our comparisons of assemblage dissimilarity indicate that invertebrate assemblages in outlet streams are relatively homogenous compared to the assemblages in inlet streams. These patterns are found in both natural lake and impoundment systems. These analyses suggest that different types of lentic disruptions of streams have a similar influence on invertebrate distribution.
KEY WORDS: benthic invertebrate, stream, lake, dam