Effects of nutrient enrichment on recruitment of age-0 fathead minnows (Pimephales promelas): potential impacts of environmental change on the Boreal Plains

• Published in: Canadian journal of fisheries and aquatic sciences 2002-05, Vol.59 (5), p.759-767
• Main Authors: Grant, Susan C.H, Tonn, William M
• Format: Article
• Language: English
• Subjects: Animal populations; Environmental changes; Environmental impact; Eutrophication; Fish; Fishing industry; Food; Food availability; Freshwater; Lakes; Land use; Nutrient concentrations; Pimephales promelas; Plankton
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f02-054

Eutrophication in lakes on the Canadian Boreal Plains is predicted to increase because of climate and land-use changes. The resulting increase in lake productivity might then increase recruitment of young fish via increased food availability, growth, and survival. To assess this hypothesis, we manipulated nutrient concentrations in experimental ponds and examined mechanisms influencing production and survival of age-0 fathead minnows (Pimephales promelas). Nutrient enrichment increased phytoplankton biomass (chlorophyll a) sevenfold in treatment compared to reference systems. In response, fish laid more eggs and survival of age-0 fish was enhanced, both of which contributed to a more than fivefold increase in total number of age-0 fish that survived to the end of the growing season in treatment versus reference systems. A complementary enclosure experiment suggested that enhanced growth and decreased susceptibility to starvation contributes to the greater survival of age-0 fish when food resources are increased. Furthermore, overwinter mortality of age-0 fathead minnows in experimental ponds was strongly size-selective; no fish smaller than 20 mm survived winter. Because of these effects on egg production and growth and survival of age-0 fish, environmental changes predicted for the Boreal Plains could significantly alter the dynamics of fish populations.