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Communication at the NABS Annual meeting, Keystone, 2000
(1) THE RELEVANCE OF HIERARCHICAL COMMUNITY STRUCTURE TO STREAM BIOASSESSMENTS WITH BENTHIC MACROINVERTEBRATES.
I.K. Ciesielka and R.C. Bailey. Department of Zoology, University of Western Ontario, London, Ontario, Canada N6A 5B7
Most bioassessments of streams using benthic macroinvertebrates [BMI] are designed with ease of use and cost efficiency in mind, allowing more stream sites to be assessed for a given time and budget. Faunal variation is often accounted for by limiting comparisons of test to reference sites within ecoregions, while local variation is limited by only sampling the riffle zone. In this context, a single, perhaps pooled observation is assumed precise and accurate enough to represent the entire site, but potentially important spatial heterogeneity in the stream is missed. This study evaluates the magnitude and nature of spatial variation in stream communities using a hierarchical approach. Ten streams [4th order] within the Upper Thames River drainage basin in Southwestern Ontario, Canada, were sampled at two sites at least 500m apart. Each site was sampled at 3 consecutive riffles and each riffle was sampled at the left edge, midstream and right edge using a 5m kick. In total, 180 samples were collected [(10 streams) X (2 sites) X (3 riffles) X (3 kicks)]. Along with the samples of BMI communities, water chemistry, substrate type and riparian vegetation were also recorded. A better understanding of how BMI community structure changes with scale will lead to protocols for more sensitive and accurate bioassessments of streams.
Presented at 1:00 PM on Monday, May 29, 2000 in Bioassessment I
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