Survival and growth of larval coastal giant salamanders (Dicamptodon tenebrosus) in streams in the oregon coast range

Published source details Sagar J.P., Olson D.H. & Schmitz R.A. (2007) Survival and growth of larval coastal giant salamanders (Dicamptodon tenebrosus) in streams in the oregon coast range. Copeia, 1, 123-130.
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This study is summarised as evidence for the following.

	Action	Category
	Install culverts or tunnels as road crossings Action Link

Install culverts or tunnels as road crossings

A replicated, controlled study in 2002–2003 of culverts along small forest streams in the Oregon Coast Range, USA (Sagar 2004, Sagar, Olson & Schmitz 2007) found that culverts were used by a small proportion of larval coastal giant salamander Dicamptodon tenebrosus. Complete culvert passage was recorded by 16 larvae at seven of nine culvert sites, although only 20% of larvae moved far enough to assess culvert passage. Growth rates and density did not differ significantly, but movements varied in streams with and without culverts. Effects on larval survival were inconclusive. Densities were lower in raised metal pipe culverts than in arch culverts with streambed substrates. Arch culverts and streams had similar densities. Density was associated with the presence of large substrates. In the presence of culverts, the direction and distance moved did not differ significantly (culvert: 3 m; none: 4 m), but larvae moved to the centre of the stream section less frequently. Nine sites with a culvert (four pipe and five arch) and five without were selected. Stream sections (80 m long) and culverts were monitored two to three times in June–August using dip-netting and visual surveys. Culverts were located at the centre of each section. A total of 2,215 larvae were measured and marked.