Influence of Land Use and Hydrologic Disturbance on Crayfish Assemblages




Role of Geodata Crawler:
Geodatacrawler was used to delineate and calculate watershed size, as well as the proportion of forested land and land converted for agriculture or urban development at the stream, riparian, and catchment scale.


Report:
Baecher JA, Leasure DR, Lynch D, Magoulick DD. 2013. Impact of Anthropogenic Land Use and Hydrologic Disturbance on Crayfish Assemblages. Report submitted for NSF Research Experience for Undergraduates program at University of Arkansas.

Funding Source:
National Science Foundation, EcoREU program.

Contribution to Education:
Undergraduate student Alex Baecher completed this project as part of the NSF Research Experience for Undergraduates program at the University of Arkansas. He produced an REU report and presentation, has since presented the work at several national scientific meetings, and is preparting the manuscript for publication in a peer reviewed journal.

Abstract:
Alterations of catchment characteristics can modify the timing, frequency, and magnitude of stream flows, which can affect ecological structure and function. Species that are subject to seasonal drying have adapted to water stress and are thus less likely to face population losses. Ecological response to land use changes have been extensively studied in aquatic insects, however the influence of land use and hydrologic disturbance on crayfish assemblages has been much less studied. We sought to determine if anthropogenic land use changes and hydrologic disturbances are associated with crayfish density in the Ozark Highlands. We hypothesized that crayfish densities will be negatively associated with hydrologic disturbance, % agriculture, and % development, and positively associated with % forested land and an index of habitat quality (RHA). Our analyses showed there was no statistically significant relationship among crayfish densities and RHA, % agriculture, % forested land, or % developed land, however total crayfish density exhibited a positive relationship with Hydrologic Disturbance Index. A positive relationship existed between adult crayfish densities and freshwater withdrawal and undeveloped land fragmentation within the watershed. A positive relationship was also found between juvenile crayfish densities and the adjusted distance to the nearest NPDES site. Total crayfish densities showed a positive relationship with freshwater withdrawal, watershed road abundance, and undeveloped land fragmentation within the watershed. The positive relationship between crayfish densities and hydrologic disturbance is likely driven by Orconectes neglectus (the dominant species at most every site), a tolerant species to stream drying and dessication.

Professional Presentations:
2014 Society for Freshwater Science Annual Meeting, Portland, Oregon
2013 Arkansas Water Resources Conference, Fayetteville, Arkansas
2013 American Fisheries Society Annual Meeting, Little Rock, Arkansas
2013 University of Arkansas Ecosystem Services Research Symposium, Fayetteville, Arkansas