Limnology Lab ZOO 4430 R. Hall/B. Taylor
Laramie River Gradient Study
For much of the course we will study streams the Laramie River basin The main goal of this study is to compare three streams in this basin with predictions from the River Continuum Concept that is (will be) presented in lecture. We will sample high-mountain, low-mountain, and a plains river to examine longitudinal changes in the physical habitat and the biota of the river system.
The goal of this study (and there will be more on this later) is to examine how biological aspects of a river change following physical attributes? How does algae respond to changing light and nutrient conditions in streams? Do we see more or less detritus as we move downstream? How might stream velocity interact with seston transport? Do functional groups of insects respond to changing algal and detrital standing stocks? All these questions and more can be answered using the data we will collect. Unfortunately most of these topics have not yet been covered in the lecture, but we have to do the field work now anyway so that we do not have to snowshoe to the mountain site!
We will measure several physical and biological parameters at each site. Because each site is so different from one another, we may need to use different techniques at each site.
Seston concentration: ash free dry mass, and % ash
Temperature, conductivity, pH and dissolved oxygen
Water for nutrients (SRP & NH4-N) and alkalinity
Geomorphology: width and depth
Stream discharge using the current meter
Substrate size: measured by pebble counts
Benthic organic matter: measured using a bottomless bucket
Standing stock of chlorophyll. We will measure this on rocks in the stream.
Macroinvertebrates: density and species composition.
Invertebrate drift: density and species composition
It is also important to examine the canopy cover and riparian vegetation at each site. We will do this using a “Mohlersky” tube.
The study sites are Libby Creek (high in the Medicine Bow mountains), the Little Laramie river east of Centennial (on Dr. Lindzey’s property) and the Big Laramie River, right here in Laramie.