Assessing Crayfish Habitat Dan O’Brien John Meredith Leroy Mims

Scientists are observing invasive crayfish displacing indigenous crayfish in the Lake Mendota Watershed. Invasive crayfish are thought to disrupt aquatic habitat for native fish and plants species. This project assesses the relationship between crayfish and their surrounding environmental variables. Are there trends in environmental habitat? Problem Statement

Project Overview Aquatic Vegetation Sinuosity Floodplain Width Riverbed Proportion Of Watershed Development Native CrayfishInvasive Crayfish

EVALUATEEVALUATE Data Sources Floodplain Width Aquatic Vegetation Proportion of Watershed Development Riverbed River Sinuosity Crayfish Methods Results Improvements

Methods: Aquatic Vegetation

Methods Aquatic Vegetation

Methods Aquatic Vegetation

Methods Aquatic Vegetation

Methods Aquatic Vegetation

(1)Determine stream segments within each Dane County subwatershed (2) Measure river-miles for each stream segment (3) Compare this length to the minimal distance from source to mouth Methods Sinuosity

Methods (1) Determine field sites (2)Measure floodplain width perpendicular to the river channel Floodplain

1.Create a buffer around the sampled sites. 2. Select the Length Slope Factors found in proximity to the sites. 3. Determine if there is a difference in tolerance to erosion. Soils Methods

1.Create a buffer around the sampled sites. 2.Select the land use types found in proximity to the crayfish. 3.Determine if there is a difference in suitable habitat between the two species. Land-use Methods

Results

Aquatic Vegetation as a Percent of Surface Area within 100 meters of Field Sites

No significant difference in sinuosity (p=.16) Results

Significant difference in Floodplain width (p=.049) Results

Length- slope factor NATIVEINVASIVE A: HIGHEST 03 B125 C51 D10 E: highest 01 X 2 Analysis (p-value is ~.20) Number of field sites for each species containing any soil-type with the following classification.

Results Land-use (p-value=.002)

Conclusion For aquatic vegetation, results are inconclusive. Results for sinuosity and riverbed substrate were promising, but not significant. However, for floodplain width and proportion of 200-m buffer in agriculture or mixed-urban land-use, we observed a difference in the habitat for invasive crayfish.

Conclusion Floodplain width and proportion of 200-m buffer in agriculture or mixed-urban land land-use: Invasive crayfish inhabit wider floodplains, implicating different watershed hydrologies. Native crayfish inhabit regions with less erodible soil-types - suggests particulate flow may be a factor.

Data Challenges Tree canopy obstructing rivers at the one site with Invasive Crayfish

Data Challenges Decision to pursue Aquatic Vegetation from Panchromatic QuickBird not made in light of field site locations Satellite images cut-off too far south to compare Invasive against Native Crayfish Images only a snapshot of time (July 31, 2004), while aquatic vegetation, the riverbanks and crayfish vary throughout the season Inherent errors built into digitization process Manual digitization Upstream vegetation

Data Challenges River velocity Land-use classification Flood-plain Questions?

Assessing Crayfish Habitat Dan O’Brien John Meredith Leroy Mims