Environmental Management

, Volume 54, Issue 5, pp 1090–1101 | Cite as

Fish Assemblage Response to a Small Dam Removal in the Eightmile River System, Connecticut, USA

  • Helen M. PoulosEmail author
  • Kate E. Miller
  • Michelle L. Kraczkowski
  • Adam W. Welchel
  • Ross Heineman
  • Barry Chernoff


We examined the effects of the Zemko Dam removal on the Eightmile River system in Salem, Connecticut, USA. The objective of this research was to quantify spatiotemporal variation in fish community composition in response to small dam removal. We sampled fish abundance over a 6-year period (2005–2010) to quantify changes in fish assemblages prior to dam removal, during drawdown, and for three years following dam removal. Fish population dynamics were examined above the dam, below the dam, and at two reference sites by indicator species analysis, mixed models, non-metric multidimensional scaling, and analysis of similarity. We observed significant shifts in fish relative abundance over time in response to dam removal. Changes in fish species composition were variable, and they occurred within 1 year of drawdown. A complete shift from lentic to lotic fishes failed to occur within 3 years after the dam was removed. However, we did observe increases in fluvial and transition (i.e., pool head, pool tail, or run) specialist fishes both upstream and downstream from the former dam site. Our results demonstrate the importance of dam removal for restoring river connectivity for fish movement. While the long-term effects of dam removal remain uncertain, we conclude that dam removals can have positive benefits on fish assemblages by enhancing river connectivity and fluvial habitat availability.


Dam removal Stream recovery Fish assemblages River restoration Connecticut 



This project was completed using combined funds from Menakka and Essel Bailey, the Schumann Foundation, The Nature Conservancy, and project grants from Wesleyan University to BC and the College of the Environment. Student support and internships were provided by the Mellon Foundation, the Hughes Foundation, and Schumann Foundations. The authors thank Valerie Marinelli and Susan Lastrina for administrative and logistical support and Sarah Donelan for field assistance.


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Helen M. Poulos
    • 1
    Email author
  • Kate E. Miller
    • 2
  • Michelle L. Kraczkowski
    • 2
  • Adam W. Welchel
    • 3
  • Ross Heineman
    • 2
  • Barry Chernoff
    • 2
    • 4
  1. 1.College of the EnvironmentWesleyan UniversityMiddletownUSA
  2. 2.Department of BiologyWesleyan UniversityMiddletownUSA
  3. 3.The Nature ConservancyNew HavenUSA
  4. 4.Department of Earth and Environmental StudiesWesleyan UniversityMiddletownUSA

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