Unequal Ranging Abilities of Prairie Fishes and Consequent Threats to the Stream Ecosystem: Impacts of Lost Connectivity in Lotic Networks

Prairie streams are dynamic systems wherein habitat patches are sporadically created and lost from regular hydrologic variability. Erratic hydrologic disturbances and extreme environmental pressures impact fish assemblage structure by regulating species abundance and distribution. Local extirpation is common and species persistence is dependent on life history traits allowing for dispersal over large areas. Loss of connectivity throughout lotic networks has severed historic movement pathways and increased local extinction risk which may impair local ecosystem function. To describe the susceptibility of small-bodied fishes to stream fragmentation and the consequent risk to ecosystem function, species-specific swimming and jumping abilities and local ecosystem effects of four ecologically distinct plains fishes were quantified. Species evaluated represent unique functional feeding guilds that have potentially different effects on ecosystem structure and function. Diverse movement capacities reveal the variable susceptibility of prairie fishes to population fragmentation by anthropogenic barriers. Continued interruption of lotic corridors will negatively impact local assemblage structure by favoring colonization of stronger swimming and jumping species, potentially impairing ecological processes of prairie streams as results suggested that fishes affected ecosystem structure differently and were not ecologically redundant. Species loss coupled with unequal recolonization probabilities will likely diminish ecosystem goods and services provided by streams.