Larch Mountain Salamander Mount Rainier National Park Amphibians have recently been a focus of concern due to the serious population declines documented world wide (Barinaga, 1990; Blaustein and Wake, 1990). Amphibians serve as good bioindicators as they live in contact with both terrestrial and aquatic ecosystems and are sensitive to changes in environmental conditions. Amphibians constitute a major portion of animal biomass in many habitats. In forested areas, they exceed the combined weight of all vertebrates. Amphibians play a key food chain role because of their large numbers and also because they occupy a high position in the food chain.
Recent literature and studies in North Cascades National Park (Liss et al., 1995), Crater Lake National Park, and Mount Rainier National Park (Hoffman, in prep) have clearly demonstrated that the multiple age classes in reproducing populations of non native salmonids have a great impact on native lake communities which evolved under fishless conditions. Fish predation affects the food webs in the lakes, altering nutrient cycling, the structures of zooplankton and benthic macroinvertebrate communities, and the distributions, behaviors and abundances of the prey taxa. Fish predation has also been shown to have a major impact on amphibian abundance, behavior and distribution, especially salamander populations, even when a fish population occurs in low density. In some cases prey taxa have been eliminated from lakes and ponds.
The loss of amphibians would have a profound affect on forest ecosystems. Ten amphibian taxa associated with aquatic systems have been documented in Mount Rainier National Park. These include Ascaphus truei, the tailed frog (tributaries), Dicamptodon tenebrosus, the Pacific giant salamander (rivers) Rana cascadae, Cascade frog (ponds), Rana aurora, red legged frog (ponds), Ambystoma gracile, northwest salamander(ponds and lakes), Ambystoma macrodactylum, long toed salamander (ponds and lakes), Taricha granulosa, roughskin newt (ponds), Bufo boreas, Western toad (wetlands, ponds), and Plethodon vandykei, Van Dyke's salamander (terrestrial breeder but found in streamsides and seeps). Two other terrestrial breeding salamanders also occur in the park: Plethodon vehiculum, red-back salamander, and Plethodon larselii, Larch Mountain slamander A parkwide survey of aquatic breeding amphibians was conducted during 1996-1999. Terrestrial amphibian surveys, focusing on two federally listed Species of Concern, were conducted from 1999 - 2002. Given the worldwide decline in amphibians (Bury et al. 1980, Blaustein et al, 1994), and identified threats in Mount Rainier National Park, we are developing long-term monitoring programs to document the distribution and abundance of certain taxa that serve as good bioindicators.