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Development of Pecos assiminea (Assiminea pecos) monitoring methods and effects of habitat restoration on Pecos assiminea at Bitter Lake National Wildlife Refuge


January 2013 - September 2015


Pecos assiminea Assiminea pecos is a tiny (< 2.1 mm) snail with a distribution limited to Chaves County, New Mexico and Pecos County, Texas. The species has been federally listed as endangered since 2005. Bitter Lakes National Wildlife Refuge is one of the few strongholds of Pecos assiminea, but knowledge of its distribution and habitat use remains incomplete. Furthermore without viable survey techniques, the status of the species and the impacts of habitat restoration activities cannot be determined. The recovery plan for Pecos assiminea calls for developing a technique to monitor its abundance, thus our primary and secondary objectives are to evaluate two surveying techniques, quadrat and wood tile sampling, for determining Pecos assiminea distribution, density, and habitat associations and to evaluate the effect of common reed removal on a suite of endangered species including Pecos assiminea, two springsnails and an amphipod (Pyrgulopsis roswellensis, Juturnia kosteri, Gammarus desparatus, respectively).

Research Products and Activities

Peer Reviewed Publications

  • Roesler EL, & TB Grabowski. 2018. Estimating factors influencing the detection probability of semi-aquatic freshwater snails using quadrat survey methods. Hydrobiologia 808:153-161. doi: 10.1007/s10750-017-3415-9 Abstract | 


  • Roesler EL. 2016. Development of habitat use data, detection, and survey methods for the endangered gastropod, Pecos assiminea (Assiminea pecos) at Bitter Lake National Wildlife Refuge. MS thesis. Texas Tech University, Lubbock, TexasDownload  | 


  • Roesler EL, D Rogowski, & TB Grabowski. Assessing habitat use patterns of the endangered snail, Pecos assiminea Assiminea pecos, at Bitter Lake National Wildlife Refuge. Joint Meeting of the Texas and Oklahoma Chapters of the American Fisheries Society. Pottsborro, Texas. 13-15 February 2014.
  • Roesler E.L., T.B. Grabowski, & D. Rogowski, Assessing habitat-use patterns and survey methodologies of the endangered snail, Pecos Assiminea, at Bitter Creek National Wildlife Refuge. Texas Tech Annual Biological Sciences Symposium. Lubbock, Texas. 29 March 2014.
  • Roesler, EL, TB Grabowski, & D Rogowski. Assessing habitat-use patterns and survey methodologies of the endangered snail, Pecos Assiminea, at Bitter Lake National Wildlife Refuge. 144th Annual Meeting of the American Fisheries Society. Quebec City, Quebec, Canada. 17-21 August 2014.
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Current Staff

Federal Staff: 95

Masters Students: 240

Phd Students: 143

Post Docs: 52

University Staff: 245

5 Year Summary

Students graduated: 702

Scientific Publications: 1948

Presentations: 4253



  • Timothy GrabowskiPrincipal Investigator
  • David RogowskiCo-Principal Investigator
  • Elizabeth RoeslerStudent

Funding Agencies

  • USGS - SSP


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey