Secluded basins and harmful conditions in the Prairie Pothole Region result in a simple fish community, with fathead minnows and brook sticklebacks being the most common species in this region. Fathead minnows are often the dominant species and experience explosive population growth with the absence of piscivorus fish and their high reproductive rate. This allows fathead minnows to reach biomass estimates ranging from 144 to 482 kg/ha during the breeding season. With both high population numbers and biomass, it is not a surprise that fathead minnows possess significant influence on the aquatic macroinvertebrate populations, one of their primary food sources. Populations of zooplankton, aquatic insects, and ostracods are greatly affected by fathead minnow predation, with peak daily consumption ranging from 10.1 to 62.6 kg/ha. Thus, fathead minnows indirectly affect species dependent on aquatic invertebrates as food, such as ducks and their young, larval salamanders, and a number of passerine birds. Higher turbidity and phytoplankton biomass also result in wetlands with the presence of fathead minnows. However, the structure of these systems is strongly dependent on the presence and abundance of fathead minnows as a low- to middle-level consumer, whether it be due to direct or indirect effects. In addition, because they are tolerant of a broad range of environmental conditions, fathead minnows are common among in a large variety of aquatic habitats throughout its geographic range. Fathead minnows represent an important food source for piscivorous fishes, as they often the only species present in human-made retention ponds due to their habitat adaptability.
Ecosystem Impact: keystone species
- Stewart, K., D. Watkinson. 2004. The Freshwater Fishes of Manitoba. Canada: University of Manitoba Press.