Spatial Ecology of Imperiled Great Plains Fishes

Abstract

I conducted a series of experiments focused on a central theme of stream fish spatial ecology in the Southern Great Plains. Movement, or physical change in location, is a spatial construct that most organisms require for survival. Prairie Chub (Macrhybopsis australis) is a suspected member of the pelagic-broadcast spawning (PBS) group of fishes that are presumed to rely on ova drift to complete their life cycle. To compensate for ova drift, PBS fishes are suspected to move some upstream distance to recolonize after downstream displacement of ova and larvae. In my first chapter, I tested the PBS upstream movement hypothesis against the widely documented restricted movement paradigm (RMP), which posits that most individuals within a population remain largely stationary over their lifetime. In my second chapter, I constructed an ecological niche model (ENM) to estimate occurrence of Prairie Chub throughout the upper Red River basin, and then couple this model with movement data from Chapter 1 to identify potential source-sink habitats throughout the basin. This chapter tested different niche concepts based primarily on Grinnellian, Eltonian, and fundamental niche definitions. I found that incorporating movement into the ENM improved accuracy of the model and enabled estimation of the geographic dimensions of Prairie Chub niche. In my third chapter, I modeled movement distributions for seven PBS species to assess differences in spatial dispersal distributions across multiple riverscapes and found that estimated movement distances correlated with previously published estimates of the minimum fragment size for persistence. All of these chapters focus on dispersal ecology along multiple spatial extents (i.e., reach, to basin, to regional scale) with the ultimate intent of linking ecological principles with conservation biology. Broadly, the results of these experiments have helped determine appropriate spatial scales for conservation and management in Great Plains rivers to sustain stream fish biodiversity.