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Amphibian communities in vernal pools, fishless lakes, and fish-containing lakes in downeast Maine, and effects of predation of Ambystoma maculatum (collaborator: A.J.K. Calhoun)

Dawn Bavaro ready to count egg masses at a fishless lake in Downeast Maine.<br />


January 2006 - December 2011


Lakes in Maine with natural and stocked fish populations support invertebrate communities that differ from those naturally without fish. The introduction of fish to historically fishless lakes also may affect the amphibian species that reside, breed, or feed in these water bodies. Introduced fish may affect amphibian species abundance and composition by changing food resources, eating the amphibians, eating aquatic insects that prey on amphibians, and by altering amphibian breeding and refuge sites. Amphibian species that are palatable to fish, for example, may be consumed by fish or may avoid fish by altering their movements in the landscape to locate alternative fishless sites. Lakes stocked with fish may become biological sinks for amphibian populations that continue to use the water bodies for egg-laying in spite of the presence of fish, resulting in their offspring, or the adults themselves, being consumed by fish. It is not clear whether there are mechanisms in naturally fishless lakes stocked with fish that allow amphibians to persist in these modified environments. Habitat characteristics such as structural complexity and egg laying sites as well as characteristics of eggs masses may affect breeding success in these permanent water bodies. Through this study, we hope to identify characteristics of Ambystoma maculatum (spotted salamander) egg masses occurring in fishless and fish-containing lakes and adjacent vernal pools and features of these habitats that make them suitable or unsuitable habitat for this species. Furthermore, we will determine if amphibian community composition differs among fishless and fish-containing lakes.
Project objectives are:
1) Characterize amphibian communities of fishless and fish-containing lakes in Maine.
2) Determine if egg mass morphology and oviposition affect Ambystoma maculatum resistance to predation.
3) Determine effects of fishless lake, fish-containing lake, and vernal pool predators on survival of Ambystoma maculatum eggs and larvae.
4) Determine fitness of adult Ambystoma maculatum adults breeding in vernal pools, fishless lakes, and fish-containing lakes.

Research Products and Activities

Peer Reviewed Publications

  • Shearin, A.F., A.J.K. Calhoun, and C.S Loftin. 2012. Evaluation of Listener-based Amphibian Surveys with Automated Audio Recording Devices. Wetlands 32:737-751. Download  | 


  • Shearin, Amanda F. Influence of landscape arrangement and wetland condition on breeding dynamics of Ambystoma maculatum (spotted salamander) in Maine, USA. Ph.D. Dissertation, Ecology and Environmental Sciences, University of Maine, Orono, 236 pp.Download  | 


  • Shearin, A., C.S. Loftin, and AJ.K. Calhoun. 2010. Amphibian Communities in Maine’s Historically Fishless Lakes: Facultative Breeding Occurrence by Vernal Pool Amphibians. 2010 Maine Water Conference, 17 March, Augusta, ME. Shearin presented.
  • Shearin, A., C. S. Loftin, A.J.K. Calhoun. Amphibian Communities in Maine’s Historically Fishless Lakes: Facultative Breeding Occurrence by Vernal Pool Amphibians. 2010 Northeast Partners in Amphibian and Reptile Conservation Conference, 10-11 August, Schoodic Research and Education Center, Acadia National Park, Maine. Shearin presented.
  • Shearin, A., C.S. Loftin, A.J.K. Calhoun. 2010. Facultative breeding occurrence by vernal pool amphibians in Maine’s fishless lakes. Presentation at The Wildlife Society 2010 Annual Meeting, Salt Lake City, Utah. 2-6 October.
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Current Staff

Federal Staff: 95

Masters Students: 239

Phd Students: 142

Post Docs: 53

University Staff: 240

5 Year Summary

Students graduated: 701

Scientific Publications: 1936

Presentations: 4260



  • Cynthia LoftinCo-Principal Investigator
  • Amanda ShearinStudent
  • Jaclyn TorzewskiStaff
  • Jennifer WhiteStaff
  • Jessica ShraderStaff

Funding Agencies

  • Cooperative Research Units
  • Maine Department of Inland Fisheries and Wildlife
  • University of Maine


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey