Honors Program


Document Type


Date of this Version

Fall 10-28-2019


Spethman, C. (2019). Cercarial Parasitism of Freshwater Snails in Sandhills Ponds versus Streams. Undergraduate Honors Thesis. University of Nebraska-Lincoln.


Copyright Caroline Emily Spethman 2019


Parasite prevalence was calculated for all aquatic snails collected from four freshwater localities in Western Nebraska from Summer 2016 to 2019: Dunwoody Pond, Haythorn Ranch, Neven’s Restoration, and Breen’s Flyaway. With data of increasing trematode cercarial infection specifically at Dunwoody Pond, this community was further studied. In Summer 2019, a total of 217 freshwater snails representing species of Physa sp., Stagnicola elodes (Say,1821), and Helisoma anceps (Menke,1830) were collected from Dunwoody Pond and Dunwoody stream, near Ogallala, Nebraska. Eighty-one snails were collected from Dunwoody Pond, 76 snails were collected 31 meters upstream, and 60 snails were collected 61 meters upstream the pond. All 217 snails were examined, and three different genera of trematode cercariae, representing several species, were identified including: Echinstoma spp. Strigea sp., and Halipegus sp. Due to lack of statistical difference at locations sampled 31 meters and 61 meters upstream from Dunwoody Pond, sample data collected from the stream were grouped as one category “stream" to facilitate comparison of data of stream versus pond. We found there is a significant difference in parasite prevalence in Physa sp. snails collected from the pond versus the stream (p < 0.00001).