Date of Graduation

12-2012

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor

Daniel D. Magoulick

Committee Member

Arthur V. Brown

Second Committee Member

Michelle A. Evans-White

Abstract

The Ozark faunal region of Missouri and Arkansas harbors a high level of aquatic biological diversity, especially in regards to endemic crayfish. Orconectes eupunctus, Orconectes marchandi, and Cambarus hubbsi are three such endemics that are threatened by a limited natural distribution and the invasions of Orconectes neglectus. I sought to determine how natural and anthropogenic factors influence these three species across multiple spatial scales. Local and landscape data were used in decision tree analyses (CART) to determine their influence effect on presence/absence and density of the three species. Predictive models were validated using k-fold cross validation. O. eupunctus presence was positively associated with factors related to stream size, current velocity, and spring discharge. Orconectes marchandi presence was predicted primarily by dolomite geology and water chemistry metrics, both of which may be related to spring flow volume. Cambarus hubbsi was associated with factors related to stream size and spring flow volume, with highest densities occurring in deep waters. Models predicting crayfish presence/absence consistently outperformed random models. Orconectes eupunctus was the rarest of the three species, occurring at only 9 sites. Orconectes marchandi was restricted to the Spring River drainage, and C. hubbsi was found in all three drainages. The models were effective in modeling rare crayfish species and the results were consistent with previous observations of the three species. Conservation attention may be necessary to protect groundwater resources and to safeguard against further invasions of O. neglectus.