Cooperative Fish and Wildlife Research Units Program: Colorado
Education, Research and Technical Assistance for Managing Our Natural Resources

Colorado Project

Field Examination of Wastewater Treatment Effluent Thermal Regimes and Effects on Reproduction of Johnny Darter Etheostoma Nigrum

March 2020 - June 2022


Participating Agencies

  • Colorado Parks & Wildlife
  • Colorado Parks and Wildlife

The ultimate goal of our study is to provide Colorado Parks and Wildlife guidance as to appropriate thermal regimes to conserve transition zone native fishes. The results will be implemented into management strategies for the conservation and recovery of native transition zone fishes.

We will characterize wastewater treatment effluent thermal effects on transition zone streams by placing temperature loggers above and below wastewater treatment facilities along the Front Range to determine potential thermal alterations. Wastewater treatment facilities will be included based on input from previous research and CPW staff—especially the Water Quality Coordinator. Critical time periods include winter and shoulder seasons (transition seasons between fall–winter and winter–spring).

We will also evaluate how altered thermal regimes are affecting reproduction of Johnny darter, Etheostoma nigrum. Field collections of Johnny darter will take place above and below wastewater treatment facilities to examine if there are differences in reproductive output. To examine seasonality of egg production, Johnny darter will be collected every month. Once collected, fish will be preserved and examined for egg production. Egg production includes number of eggs produced, size of eggs, developmental stage of eggs, and timing of egg production.

Research Publications Publication Date
Adams, C.M., D.L. Winkelman, P.A. Schaffer, D.L. Villeneuve, J.E. Cavallin, M. Ellman, K.S. Rodriguez, and R.M. Fitzpatrick. 2022. Elevated winter stream temperatures below wastewater treatment plants shift reproductive development of female Johnny Darter Etheostoma nigrum: A field and histological approach. Fishes:7-361 DOI: 10.3390/fishes7060361. | Download November 2022