Clancy BrownClancy BrownWilliam Smith CollegeWilliam Smith College

Rocky Mountain Biological LabRocky Mountain Biological LabMentor: Brad W. TaylorMentor: Brad W. Taylor

Effect of the nuisance diatom Effect of the nuisance diatom Didymosphenia geminataDidymosphenia geminata

on invertebrates on invertebrates in the East Riverin the East River

What is Didymo?What is Didymo?

Image: Sarah Kiemle, Michigan Tech University

Other diatom species; growing attached to stalk

Didymo stalk

Didymo cells

Blooms of Rock Snot?Blooms of Rock Snot?

Map: Sarah Spaulding, USGS

QuestionsQuestions

(1)Does D. geminata alter the composition and abundance of stream invertebrates?

(2) Does D. geminata affect the growth rate of stream invertebrates?

Removal PlotsRemoval PlotsUpstream

Downstream

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I’m good at removing didymo!I’m good at removing didymo!

18-Jun 25-Jun 02-Jul 09-Jul 16-Jul 23-Jul 30-Jul

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Removal

D. geminata

D. geminata

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Three invertebrate species showed Three invertebrate species showed habitat selectionhabitat selection

E. longimanusE. longimanus

ChironomidaeChironomidae

HesperoperlaHesperoperlapacificapacifica

Didymo has no effect on species Didymo has no effect on species richnessrichness

Two Experiments in the East River:Two Experiments in the East River:

Growth ChambersGrowth Chambers Baetis spp N = 6 chambers/treatment

Epeorus longimanus N = 9 chambers/treatment

Epeorus longimanusEpeorus longimanus shows a trend shows a trend towards slower growth rate in Didymotowards slower growth rate in Didymo

Didymo has no effect on the growth rate Didymo has no effect on the growth rate of of Baetis sppBaetis spp

Summary: Effect of Summary: Effect of D. geminataD. geminata on stream invertebrateson stream invertebrates

(1) Composition and abundance

- More Chironomidae and stoneflies (Hesperoperla), but fewer E. longimanus in D. geminata treatment

- No difference in species richness

(2) Growth rate

- A trend for slower growth in E. longimanus - No significant effect on Baetis spp

AcknowledgementsAcknowledgements

Brad W. TaylorBrad W. TaylorThe “Benthettes”The “Benthettes”The National Science FoundationThe National Science FoundationRocky Mountain Biological LaboratoryRocky Mountain Biological Laboratory