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.