Temperature and winter duration requirements for reproductive success in Johnny Darter Etheostoma nigrum in the South Platte River Basin, Colorado
Date
2021
Authors
Baum, Carli M., author
Winkelman, Dana L., advisor
Bestgen, Kevin R., committee member
Hess, Ann M., committee member
Myrick, Christopher A., committee member
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Abstract
Changes in water temperature and its seasonal timing influences the physiological processes of many aquatic ectotherms. Wastewater treatment plants (WWTP) along Front Range streams of Colorado have contributed to warmer and more consistent water temperatures throughout the year, particularly in winter months. Reduced variation in seasonal temperatures may have adverse effects on fishes that rely on temperature fluctuations or sustained periods of specific overwinter temperatures for reproductive cues and proper gonadal development. Assessing thermal requirements for reproduction is necessary for the conservation of native warmwater fishes residing in WWTP effluent-impacted streams. Johnny Darter Etheostoma nigrum are used as a sentinel species to assess winter water temperature regulations in Colorado because they are a thermally sensitive native species; however, their winter temperature requirements for successful reproduction are not known. Therefore, I evaluated the effects of winter stream temperature and winter duration on Johnny Darter reproductive success in the laboratory. Winter duration and temperature treatments simulated warmed effluent-impacted streams as well as streams with a natural thermal regime. Data indicated winter temperature and duration influenced timing of reproduction and egg development. Earlier spawning initiation was observed in fish exposed to warm winters and along with longer development time of eggs spawned at cooler water temperatures. Egg and larval production was similar among treatments and indicates that the current winter water temperature standard may be adequate. However, reproductive output needs to be evaluated in the context of seasonal timing because spawning timing has the potential to effect overall production, egg development and survival.
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Subject
fisheries
fisheries management
urbanization
fisheries conservation
ecology
Plains fishes