Research About amphibians

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Distribution of Van Dyke’s salamander (Plethodon vandykei).

A survey is being conducted to document the distribution of Plethodon vandykei and factors correlated with its occurrence. This will entail visiting all known populations in Mount St. Helens National Volcanic Monument, searching for additional populations in the Monument, and recording aspects of the habitat associated with each population visited. By providing a more complete picture of the distribution of the salamander than is presently available, the proposed study will permit monitoring and further study of this species’ populations and also enhance understanding of its habitat associations.

 

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Posted On: Filed Under: Biological Research

Cave biology in the Mount St. Helens Cave Basalt lava flow

This study seeks to establish an inventory of species inhabiting and using lava tubes and caves in the Cave Basalt lava flow. Bat populations in caves are dominated by Plecotus townsendii. Of small mammal species inhabiting or using caves, deer mice (Peromyscus maniculatus) are most wide spread. Few amphibians were observed; the most significant amphibian finding was a population of Larch Mountain salamander (Plethodon larselli). 256 invertebrate species of which approximately 100 species are arthropods have been collected in caves.

 

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The herpetofauna of Mount St. Helens: survival and colonization following the 1980 eruption.

This study documents the survival and colonization of reptiles and amphibians in areas impacted by the 1980 eruption of Mount St. Helens. Surveys were conducted at 15 locations, with representative sites in three distinct volcanic impact zones, 1) ashfall, 2) blowdown, and 3) blast, during spring and summer from 1980 through 1991. Twelve species of herptiles (9 amphibians, 3 reptiles) are considered to have survived volcanic influences ranging from the directed blast to the accumulation of ash in otherwise unaltered habitats. These survivors represent most of a hypothetical list of 16 species considered to have occurred in the area before the eruption. Generally, surviving species were characterized by being more aquatic than those not found and this was attributed to the thermal buffering capacity of cool ice and snow covered aquatic systems where individuals were protected from the hot volcanic gases.

 

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Observation of recolonization of amphibians and reptiles in North Fork Toutle River debris avalanche.

Various reports indicate in situ survival of or early migration of some amphibians into regions of the blast zone following the major eruptions on May 1980. Investigators observed salamanders, frogs and toads as early as 1980 and 1981 in areas of heavy ashfall northeast of the crater. Survival at higher elevations likely was favored by snow and ice cover and the fact that many animals were in hibernacula.

 

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Recovery of stream ecosystems following catastrophic disturbances

This study was conducted in the Clearwater basin of Mount St. Helens. Three projects within the study investigate recovery of trout and sculpin populations, tailed frog populations, and invertebrate populations. Trout were studied in the main channel of Clearwater Creek, and the effects of large woody debris in the stream on fish populations were examined. Trout populations were still low as of 1990, being one-tenth to 20% of that in undisturbed stream systems; this appears largely due to interruption of spawning in years following the blast and to continuing lack of spawning habitat. Trout densities were found to be higher in areas with lots of woody debris. The condition of trout was high throughout the stream in years since 1984 presumably due to rapid recovery of high abundance of invertebrate prey. By 1985 sculpin densities were as high as or higher than in undisturbed streams.

 

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Ecology of the tadpoles of the tailed frog (Ascaphus truei)

Data on the microhabitat parameters, especially pertaining to flow rate and substrate characteristics, of the stream-inhabiting tadpoles of the tailed frog (Ascaphus truei) were collected at two tributaries of Clearwater Creek at Mount St. Helens, Washington and at Parker Creek on Mary’s Peak, Benton County, Oregon. This is the only tadpole in North America that is highly specialized for maintaining position and feeding from algae while attached to rocks via an enlarged oral disc with many rows of labial teeth. Positions of tadpoles in the streams were correlated with oral morphology and associated anatomy. Because of the length of the larval period of Ascaphus, there are usually 2 to 3 yearly cohorts in the streams at one time. We hypothesized that the interaction of the abilities of the tadpoles to adhere to rocky substrates and the size of the tadpole would result in microhabitat segregation. Whether small or large tadpoles occupied fast versus slow water would depend on the growth pattern of the tadpole (drag) versus the changes of the adhesive abilities with size.

 

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