Influence of an Invasive Crayfish Species on Diurnal Habitat Use and Selection by a Native Crayfish Species in an Ozark Stream

Abstract

Abstract The crayfish Orconectes neglectus chaenodactylus has recently been introduced into the Spring River drainage in southern Missouri and northern Arkansas and appears to be displacing the native species O. eupunctus. To determine if O. eupunctus and O. neglectus chaenodactylus compete for habitat, we examined if either species shift habitats when in the presence of one another. Habitat use of juvenile and adult crayfish was determined in six habitat types (backwater, pool, riffle, run, stream margin and vegetation) with a quadrat sampler during July/August 2003 at three sites: (1) an upstream site where O. neglectus chaenodactylus occurs, (2) a zone of overlap where both species occur and (3) a downstream site where O. eupunctus occurs. Habitat selection was determined by comparing habitat use to habitat availability. Redundancy Analyses were used to determine the relationship between crayfish densities and measured environmental variables (current velocity, water depth and percent boulder, cobble, ...