Densities of tailed frog tadpoles in small streams following watershed disturbance
Journal of the North American Benthological Society
densities, tailed frog tadpoles, small streams, watershed distrubance
Streams near Mt. St. Helens, Washington, differ in degree of watershed disturbance caused by the 1980 eruption. Summer densities of tailed frog tadpoles (Ascaphus truei) varied considerably both within and between several of these streams. Differences in density among streams were most clearly associated with differences in extent of forest in the basin. Streams in basins with little forest had maximum temperatures near 20°C and few Ascaphus. In completely or partially forested basins, maximum stream temperatures were <18°C, and tadpole densities were relatively high. Variation in density within streams was associated with substrate size, substrate embeddedness, and current speed. In many watersheds near Mt. St. Helens, Ascaphus is apparently locally extinct or nearly so. Reestablishment of populations in these watersheds may require several decades because of (1) the time required for habitat recovery and (2) the poor dispersal abilities of adults.
Hawkins, C.P., L.J. Gottshalk, and S.S. Brown. 1988. Densities of tailed frog tadpoles in small streams following watershed disturbance. Journal of the North American Benthological Society 7:246-252