Response of stream-breeding salamander larvae to sediment deposition in southern Appalachian (U.S.A.) headwater streams

1. Increased fine sediment deposition is a prevalent threat to stream biodiversity and has been shown to impact stream-breeding salamanders negatively. However, their complex life histories make it difficult to determine which stage is affected. 2. We conducted field experiments from 26 August to 11 September 2010 and 11 October to 11 November 2010 in two southern Appalachian headwater streams (U.S.A.) to examine the response of larval salamanders to increased fine sediment deposition. Fine sediment was increased in artificial stream channels by 0, 33 and 67%. The number of larvae observed at the end of the experiments was used to determine whether larval microhabitat selection was influenced by fine sediment deposition. A concurrent survey of aquatic larvae in three nearby streams complemented this experiment. Stream substratum composition at survey sites was quantified to examine the effects of fine sediment on larval salamander abundance. 3. Increases in fine sediment deposition failed to explain the number of larval salamanders detected in stream channels. Similarly, a negligible effect of fine sediment was observed on abundance estimates. 4. These results suggest that fine sediment deposition has a minimal impact on aquatic salamander larvae. Therefore, the effects of increased fine sediment loads on stream-breeding salamanders may not be the result of deleterious effects on the aquatic larvae but instead may be the result of effects on other stages. Management efforts that consider these other stages are therefore needed to protect stream-breeding salamander communities.