Clancy Brown

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Effect of the nuisance diatom Didymosphenia
geminata on invertebrates in the East River

• Clancy Brown
• William Smith College
• Rocky Mountain Biological Lab
• Mentor Brad W. Taylor

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What is Didymo?
Other diatom species growing attached to stalk
Didymo cells
Didymo stalk
Image Sarah Kiemle, Michigan Tech University
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Blooms of Rock Snot?
Map Sarah Spaulding, USGS
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Questions

• Does D. geminata alter the composition and
  abundance of stream invertebrates?
• (2) Does D. geminata affect the growth rate of
  stream invertebrates?

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Upstream

• Removal Plots

D
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Downstream
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Im good at removing didymo!
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Three invertebrate species showed habitat
selection
Chironomidae
E. longimanus
Hesperoperlapacifica
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Didymo has no effect on species richness
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• Two Experiments in the East River
• Growth Chambers

Baetis spp N 6 chambers/treatment Epeorus
longimanus N 9 chambers/treatment
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Epeorus longimanus shows a trend towards slower
growth rate in Didymo
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Didymo has no effect on the growth rate of Baetis
spp
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Summary Effect of D. geminata on stream
invertebrates

• Composition and abundance
• - More Chironomidae and stoneflies
  (Hesperoperla), but fewer E. longimanus in D.
  geminata treatment
• No difference in species richness
• Growth rate
• A trend for slower growth in E. longimanus
• No significant effect on Baetis spp

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Acknowledgements

• Brad W. Taylor
• The Benthettes
• The National Science Foundation
• Rocky Mountain Biological Laboratory