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Disturbance and Recovery of an Algal Assemblage Following Flooding in an Oklahoma Stream
Mary E. Power and Arthur J. Stewart
The American Midland Naturalist
Vol. 117, No. 2 (Apr., 1987), pp. 333-345
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2425975
Page Count: 13
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Algae at 170 fixed sites on the bed of an Oklahoma stream were monitored 1 day before, 4 days after, and 24-26 days after a large flood. Before the flood, 81% of the sampled sites had macroscopically detectable algae. Four days after the flood, algae were macroscopically detected on only 26% of sampled sites. The proportion of sites retaining algae after the flood increased with sediment size, but did not differ between pool and riffle habitats. Rhizoclonium and Spirogyra, filamentous green algae that predominated before the flood, decreased fourfold and 20-fold in frequency of occurrence, respectively. Tumbling experiments indicated that intrinsic differences in resistance to abrasion contributed to the significant differences in impact of the flood on these two algae. After the 24-26 day recovery period, algae were detected on 66% of the sites. Spirogyra replaced Rhizoclonium on 39% of the sites in pools where Rhizoclonium had dominated 4 days after the flood. Spirogyra did not replace Rhizoclonium at riffle sites, and Rhizoclonium did not replace Spirogyra at any site. Replacement of Rhizoclonium by Spirogyra in pools but not in riffles restored distribution patterns of these two algae before the flood.
The American Midland Naturalist © 1987 The University of Notre Dame