Effects of Urbanization on Stream Salamander Habitat Selection: An Experimental Study

Abstract

Salamanders are often top predators in headwater stream habitats where they are important biological indicators of stream quality, and in that regard, can be greatly affected by increased sediments and decreased riparian forests associated with urban development. In this experimental study, we examined effects of three common factors affecting salamander habitat in urbanized streams -the presence of concrete, leaf litter supply, and substrate embeddedness on the colonization of larval northern two-lined salamanders [Eurycea bislineata (Green, 1818)] and their macroinvertebrate prey, during summer 2006. We created artificial habitats that modeled completely embedded, partially embedded, and non-embedded stream substrate which were duplicated with and without leaf litter, and placed along a 382 m transect in Haskell Run, a second-order tributary of the Cuyahoga River. The natural physical features, including canopy cover and embeddedness, of the stream three meters upstream of each treatment were also characterized. The presence of concrete, and leaf litter, as well as invertebrate density, showed no significant effects on salamander density. However, canopy cover was positively correlated to salamander density. The most important factor we found influencing salamander density was embeddedness; salamander densities were significantly higher in non-embedded habitats (ANCQVA, p=O.OI7). Consequently, increased sedimentation in streams creates an undesirable habitat for stream salamanders, and precautions should be taken during urban development to preserve suitable habitats and natural headwater stream health.