Date of Award

8-2003

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology and Environmental Sciences

Advisor

Aram J.K. Calhoun

Second Committee Member

Malcolm L. Hunter, Jr.

Third Committee Member

William E. Glanz

Abstract

Many amphibians rely on wetlands for reproduction and the differential distribution of amphibian species along a gradient of wetland permanence is striking, yet not absolute. Wood frogs (Rana sylvatica) and spotted salamanders (Ambystoma maculatum) are thought to rely on seasonal wetlands for greatest breeding success, but there is little documentation of their reliance on these or other habitats. In my first chapter, I studied these species in wetlands across a hydrologic gradient from seasonal wetlands of short flood duration to permanently flooded sites. My results indicate that wood frogs have greatest reproductive effort and success in seasonal wetlands of short flood duration; however, for spotted salamanders, greatest reproductive effort occurs in some permanently flooded wetlands as well as seasonal wetlands of long flood duration. In chapter 2, 1 investigated hydrological characteristics and landscape setting of breeding pools for wood frogs and spotted salamanders. High numbers of wood frog egg masses were associated with variables that are all typical of seasonal wetlands that consistently dry in early to mid-summer, whereas high numbers of spotted salamander egg masses were associated with variables that are indicative of more permanently flooded wetlands. I developed a series of decision rules that predict how pool and landscape characteristics constrain breeding population size in pools for a subset of the sites; I then validated these decision trees with the remainder of the study sites. In Chapter 3, 1 evaluated the efficiency at documenting species presence or in capturing individuals for 4 larval sampling techniques. I compared the use of dip nets, pipe samplers, funnel traps, and bottle traps. Funnel traps had the highest probability of detection for a given level of effort (i.e., number of stations) across species. Depending on the species, bottle traps, dip nets, or pipe samplers had the lowest probability of detection per unit effort. Funnel traps or pipe samplers generally captured the highest number of individuals for a given species; dip nets or bottle traps typically yielded the lowest numbers of individuals across species.

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