Hydroperiod of Wetlands and Reproduction in Wood Frogs (Rana slvatica) and Spotted Salamanders (Ambystoma maculatum)

Kolozsvary, Mary

ôMany 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, I 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 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, I 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.ö The following are recomendations at the end of chapter 1: ôàthus my study supports the current consensus that conservationists or managers should focus conservation of pool-breeding amphibians on a landscape approach and treat groups of ponds instead of individual ponds as a conservation unitàSeasonal wetlands providing varying opportunities for metamorph production in pool-breeding amphibians that is largely dependant on weather conditions in a given yearàthus a ôgroups of pondsö approach to conservation of these assemblages will potentially provide successful production of metamorphs for the various species, at least somewhere in the group of ponds in a given year.ö GPS coordinates are available for approximate study locations in UTMs in appendix A. Site populations abundance and physical, landscape, and hydrologic pool characteristics are available in appendix B. Study site locations mentioned below are not all inclusive as many have a numerical code and, therefore, are not included. /STUDY LOCATIONS:/ /ACADIA NATIONAL PARK / / MOUNT DESERT ISLAND / Aram's / Becky's / Beehive / Bill's Winterberry / Breakneck Pond / Bruce / Bubble / Compass Harbor / Duck Pond / Eagle Lake / Otter Cliff / Fawn Pond / Gilley / George Trail / Halfmoon Pond / Hunter's Brook / Lake Wood / Leech / Lifesaver / Long Pond / Mill Field Reservoir / Pinocchio / Witch Hole / Richardson Brook / Round Pond / Sand Beach / Schooner Head / Seal Cove / Sieur de Mont / The Tarn / The Bowl / Top of the Hill Tarn / West Otter Creek / Western MTn. Road /