Rock weirs habitat heterogeneity
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Rock Weirs & Habitat Heterogeneity. Cache River. Cache Weirs. Installed in an attempt to save Heron Pond by: Raising stream bed elevation by depositing sediment Recent research indicates an overall loss of 2ft since 1996 Directing erosion away from Heron Pond

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Rock Weirs & Habitat Heterogeneity

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Rock Weirs &Habitat Heterogeneity

Cache River


Cache Weirs

  • Installed in an attempt to save Heron Pond by:

    • Raising stream bed elevation by depositing sediment

      • Recent research indicates an overall loss of 2ft since 1996

    • Directing erosion away from Heron Pond

      • Bank erosion continues at a rate of .10/ft per year

    • Stepping stream more gradually

    • Reducing stream power


Fish ladders, locks and dams……..

The current trend in the WEST is to tear out as many of these as possible.


Lots of Questions

  • Why are we putting hard structures into the stream?

  • How have the weirs affected the physical environment?

  • Have the weirs improved the hydrology? If so for how long?


I thought I was interested in Hydrology

And then research happened!


Restoration Ecology

  • Efforts are often driven by very specific goals

  • Preservation of one species can have negative consequences on others

  • Variables are numerous

  • Action taken

  • Pre and post research is difficult to complete

  • Lack of funding

  • Too many variables

  • Lack of knowledge about pre disturbancelandscape and biology

  • Evaluation nonexistent or incomplete

Decisions

Research


Cache Weirs

  • Weirs have been shown to increase Macroinvertebrate biomass but not biodiversity as the habitat heterogeneity hypothesis suggests (Walter & Wiles 2008)

Heterogeneity Hyothesis

(MacArthur & MacArthur 1961)


Proposed strategy for sequencing stream rehabilitation techniques

(Roni & Hanson, 2008)


It’s a lot like….

Wildlife science: gaining reliable knowledge (Romesberg 1981)

“Wildlife science must try the H-D method. Without it the ability to detect errors in pronouncements of laws, the self-correcting feature science must have, is fatally lacking. All learning takes place in a feedback system in which ideas and reality interplay. The method of retroduction coupled with the H-D method is such a feedback system. Uncouple them and the ability to learn, to tell error from truth, is hindered, if not destroyed.”


Proposal

  • Are the two significantly different as assumed?

  • How much habitat heterogeneity is present at each location type?

  • Study physical habitat of weir and non-weir sites

  • Assess discharge

  • Bank width

  • Depth

  • Canopy cover, etc


At the Cache

  • Restoration

  • Conservation

  • Preservation

Complex overlap of disciplines-

hydrology

biology

ecology:

landscape

restoration

engineering

economics

Photo used without permission !


The end


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