Jeff Muehlbauer’s Research-Effects of knickpoints and salt slug discharge measurements on macroinvertebrates |
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Contact me: jeffreym [at] unc [dot] edu |
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A nice example of a knickpoint on Battle Creek, on UNC’s campus. Note the boot and hand for scale. |
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Mailing Address UNC Curriculum for the Environment & Ecology CB 3275 Chapel Hill, NC 27599, USA |
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Physical Address 307 Whitehead Hall (Corner of Columbia St & South Rd) |
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Last update: 16 May 2012 |
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Home | CV | Research | Publications |
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Research Projects
Knickpoints/Salt slugs
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Another knickpoint, this one cutting through saprolite. Lab mate Daisy Small says “this wasn’t here a year ago!” |
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Sometimes the cause of a knickpoint is obvious. Here’s the likely culprit behind the one on the top right. |
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As if we needed more evidence that some of these knickpoints were in very urban locations, one day this site turned fluorescent green (assistant Ben Bogardus was perplexed). It turns out the stormwater guys were testing sewer lines on campus. Nice. I left them a voicemail saying something like “Uhh, guys, I think you’ve got a leak somewhere…” |
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The primary purpose of this project was to establish how knickpoints structured in-stream macroinvertebrate communities. Knickpoints are essentially small waterfalls that are formed by some kind of channel disturbance or downstream base level change (they are also called headcuts). This was part of my master’s research at UNC, under the advisement of Dr. Martin Doyle. Interestingly, we found that knickpoints have some influence on community structure, primarily by providing habitat for filtering taxa (like Hydropsychid caddisflies). But this effect was dwarfed completely be the knickpoint’s location: urban knickpoints and forested ones differed strongly in their community composition, despite being geographically very near one another. This research has been published in Freshwater Science/J-NABS (see my pubs page). As an aside, this project also offered an opportunity to measure the effects of salt slug discharge measurements on macroinvertebrate communities. “Salt slugs” are basically large dumps of brine solution, which is tracked at a downstream distance from the injection point to measure stream discharge. We were curious if such additions might affect macroinvertebrate communities in terms of commonly used community metrics. It turns out, they didn’t. This research was part of a collaboration with Jon Duncan at UNC, and was recently published in River Research and Applications (see my pubs page). |