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Thursday, May 29, 2008 - 4:30 PM
601
Changes in the composition and growth of invertebrates in rocky mountain streams due to blooms of the nuisance diatom Didymosphenia geminata
Clancy A. Brown, Rocky Mountain Biological Laboratory, Crested Butte, CO 81224 and Brad W. Taylor, Department of Biological Sciences, Dartmouth College, Hanover, NH 03755.
Nuisance blooms and introductions of the stalked diatom Didymosphenia geminata may be disrupting river food webs worldwide. We tested the effects of D. geminata blooms on invertebrate composition and growth in western Colorado streams, using a removal experiment, instantaneous growth rate experiments, and comparisons between natural streams. We hypothesized that the effects of D. geminata would differ among invertebrate taxa depending on their morphology, mobility, and feeding habits. D. geminata had no effect on rarefied taxa richness, but it did alter the relative abundances of taxa. Chironomids and a perlid stonefly, Hesperoperla pacifica, were more abundant in areas with D. geminata compared to areas where D. geminata was experimentally removed. In contrast, abundances of heptageniid mayflies, the dominant insect by biomass, were less abundant in areas with D. geminata present compared to areas with D. geminata removed. Heptageniid growth rates were variable but reduced by D. geminata. Abundances and growth rates of the numerically abundant, highly mobile baetid mayfly were similar between areas and treatments regardless of the presence of D. geminata. Our data show that this diatom is changing invertebrate assemblages of Rocky Mountain streams.
Web Page: Didymosphenia geminata, invertebrates, diatom
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See more of The Nabs 56th Annual Meeting (25-28 May, 2008)