Ecology of crayfishes in the Ozark Highlands ecoregion of Oklahoma

Abstract

Crayfishes aid in the transfer of nutrients through aquatic ecosystems and are prey to many aquatic and terrestrial species. Although their importance in ecosystem dynamics is generally well recognized, information about the distribution and life-history for many species is unknown. My study objectives were 1) to determine habitat use by an assemblage of tertiary burrowing crayfishes of the western Ozark Highlands ecoregion, and 2) assess the general life history and microhabitat selection of F. nana, F. macrus, and F. meeki brevis. I used a hierarchical occupancy modeling framework to determine shared and species-specific physicochemical relationships for 7 Faxonius spp. All 7 crayfishes were generally associated with reaches of mid-order streams that had relatively wide and shallow channels and with the presence of Smallmouth Bass Micropterus dolomieu. F. neglectus and F. virilis are known invaders and were more tolerable of conditions indicative of local disturbance (i.e., increased pool habitat, soil with high runoff potential, high bank angles) than other native crayfishes. I sampled three creeks monthly to determine life-history patterns. I also assessed microhabitat use and habitat availability during spring and summer. On average, F. nana and F. macrus were smaller than F. meeki brevis. Reproductively active F. nana and F. macrus were observed in higher counts during late autumn and early spring, whereas F. meeki brevis appeared to have low levels of reproductively active individuals throughout the year. F. meeki brevis selected shallow microhabitats during spring and summer, whereas F. nana selected high-velocity microhabitats during the summer and low-velocity microhabitats during spring. My results indicate important species-specific habitat relationships and life-history patterns that will be beneficial to species status assessments. Moreover, the relationships associated with the known invaders may be useful for developing mitigation strategies in areas where they have become invasive.