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Natural disturbances and fish: Local and regional influences on winterkill of fathead minnows, Pimephales promelas, in boreal lakes

  • Author(s) / Creator(s)
  • We investigated the population dynamics of fathead minnow Pimephales promelas and the environmental factors of four small lakes in the boreal forest of Alberta, Canada, for 5 years to determine the influence of local and regional factors on the development of hypoxia and the occurrence of fish winterkill. Fathead minnow densities varied considerably among lakes and years, with dramatic (47–94%) year-to-year declines occurring when dissolved oxygen levels were extremely low in the intervening winter. Large declines (presumed winterkills) occurred after 25% of the ‘‘lake-winters,’’ affecting three of four study lakes and 2 of 5 years. A fifth population in the same region, monitored for 15 years, displayed both a comparable frequency and temporal synchrony of large density decreases, suggesting that winterkill is a pervasive natural disturbance in small lakes of the Boreal Plains. In contrast to patterns displayed by larger fish species, smaller individuals in the fathead minnow populations were more strongly affected than larger individuals. Oxygen levels in a given lake and winter were related to (1) the collective interactions of productivity and depth of the lake, (2) the local and regional hydrogeology, and (3) the current and antecedent climate. As a result, the relative effects of these local and regional factors strongly influence the natural dynamics of fathead minnow populations in these lakes. Given that humans can alter many of the important factors, the natural incidence of winterkill could be augmented if human activities are poorly managed.

  • Date created
    2003
  • Subjects / Keywords
  • Type of Item
    Article (Published)
  • DOI
    https://doi.org/10.7939/R3FW0V
  • License
    © Copyright by the American Fisheries Society 2003
  • Language
  • Citation for previous publication
    • A Danylchuk and WM Tonn. "Natural disturbances and fish: Local and regional influences on winterkill of fathead minnows, Pimephales promelas, in boreal lakes." Transactions of the American Fisheries Society 132 (2003): 289-298.