Date of Graduation

Spring 2010


Master of Science in Biology



Committee Chair

John Havel


bioassay, contaminants, sediment toxicology, sublethal effects, toxic metals

Subject Categories



Biomonitoring uses living organisms to examine impacts of pollution and has been applied to studying the multiple impacts of sediment-bound toxic metals on invertebrate animals living in freshwater. Despite prior work on the behavioral and physiological responses of snails to toxic metals, little is known about the sublethal effects of stream sediments on life history of snails. The objective of the current study was to investigate the effects of metal-contaminated sediments on growth and behavior of the freshwater pulmonate snail Lymnaea stagnalis. I collected sediments from five sites along Pearson Creek, Greene County, Missouri, which is known to be affected by lead and zinc in old mine tailings. In the first experiment, I grew snail hatchlings for 97 days and, surprisingly, found increased growth rates among snails exposed to the most heavily contaminated sediments. After evaluating L. stagnalis for antipredator behaviors in response to predator cues, I tested its predator-avoidance ability following exposure to stream sediments. Results suggest that this behavioral response is depressed by contaminated sediments, with a 16% reduction in response to predator cues relative to clean downstream sediments. Overall, the current study shows that contaminated sediments can affect the fitness of freshwater snails, by affecting growth and depressing antipredator behavior.


© Sarah Elizabeth Davis

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