Structure and function of a benthic invertebrate stream community as influenced by beaver (Castor canadensis)
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Authors: D. M. McDowell, and R. J. Naiman
Date: 1986
Journal: Oecologia
Volume: 68
Number: 4
Pages: 481-489
Summary of Methods: The effects of beaver activity on the benthic invertebrate community of a small woodland stream were investigated in the Beaver Creek study area located on the Gulf of St. Lawrence in northeastern Quebec. The study area was divided into 4 sites: upstream riffle 100 m from dam (a high gradient site with complete canopy cover), the reach (a low gradient site with sedge meadows), the beaver pond (with fine sediments, large quantity wood and little canopy), and the final site was a downstream riffle (similar to upstream riffle except for a more complete canopy and greater water velocities). Benthic samples were collected in June, July and October during the ice-free period for measuring water depth, channel width, water velocity, and water temperature. Level of chlorophyll-a, invertebrate diversity indices, and biomass was determined. Particulate organic matter was separated into coarse, fine, and very fine particulate organic matter.
Article Summary / Main Points: In low order streams, dam construction and wood input by beaver generates many modifications to lotic habitats. During ice-free season of spring and summer the amount of Course Particulate Organic Matter (OM) was 2-5 times greater in impounded sites than riffle sites whereas in all seasons Fine Particulate OM and Very Fine Particulate OM levels were 3-10 times greater in impounded sites. Chlorophyll-a did not differ among sites but total density and biomass of invertebrates in the impoundments were 2-5 times greater than riffle sites in spring and summer but similar in the fall. In autumn, genetic diversity was greater in unaltered sites.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Streams Invertebrates Beavers
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: beaver, castor canadensis, benthic invertebrate community, quebec, organic matter, density, biomass
Annotation: The results of the study can be applied to lotic habitats created by beaver activity. There was no time reference in this study to how long the stream had been obstructed or how long it had been since a flushing event; this limits the application of these results.
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