Master's Theses

Document Type


Date of Award

Spring 2012

Degree Name

Master of Science (MS)




Dr. William Stark


The status of many aquatic gastropods in North America is not well understood. Many are exposed to threats similar to those that affect bivalves and other aquatic macroinvertebrates. The delta hydrobe (Probythinella emarginata) is a gill-breathing (prosobranch) snail that occurs in the northeastern United States and eastern Canada. It is 1 of only 5 species of prosobranchs in Kansas and is highly sensitive to changes in water quality within watersheds. Probythinella emarginata is presumed to be a Pleistocene relic in the state; it was first collected alive in Kansas in 2001 within Cedar Creek, Chase County, Kansas. I surveyed 13 sites on Cedar Creek, a second-order stream in the Flint Hills region of tallgrass prairie, in an effort to delineate the distribution and habitat preference of P. emarginata. In addition, 38 sites near Cedar Creek and in adjacent basins in southeastern Kansas were surveyed. Eleven species of freshwater gastropods were collected; P. emarginata was collected alive only in Cedar Creek, Chase County, and the Elk River, Montgomery County. Probythinella emarginata was the most abundant valve collected in Cedar Creek, but only 2 of 604 valves collected represented live individuals. This population, as judged by previous collections, has experienced a decline since 2001. Individuals from the Elk River population were collected among algae-covered bedrock in the lower portion of the basin. Densities of 3.7/m2 and 24.2/m2 were quantified from 2 sites in the Elk River but were restricted to downstream locations. Probythinella emarginata in the Elk River was positively associated with dissolved oxygen and negatively associated with edge-water habitat. The historical range retraction and habitat iii restrictions of P. emarginata within both streams, and the decline in the Cedar Creek population, indicate this is a rare species vulnerable to extirpation from Kansas.


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© 2012 Bryan Sowards

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