Amphibians under threat: climate change and salamanders

Posted on December 28, 2013

There’s growing evidence that amphibian populations around the world are in decline, and in several cases climate change has been linked to such declines. Long-term data sets are needed to detect significant population trends. However, almost all existing long-term amphibian population data relate to pond-breeding species, even though stream-dwelling forms contribute a significant fraction of all species (e.g., c. 35% in the U.S.A.). In a 12-year study of the spring salamander (Gyrinophilus porphyriticus), a stream-living amphibian with an extensive range from Alabama to Quebec, summer surveys were conducted at Merrill Brook, a fishless headwater stream in New Hampshire. Salamanders were found by turning over rocks. Regression analysis was used to examine whether salamander numbers were related to the total rainfall or the mean air temperature over the previous year. Larval abundance showed no long-term trend but there was a significant decline in adult abundance over the 12-year period, which meant that progressively fewer larvae were surviving metamorphosis. Adult abundance was negatively related to rainfall, which implied that an increase in the volume and frequency of spring and autumn floods had caused a drop in recruitment. Metamorphosing salamanders are more vulnerable to flash flooding than the larvae, which can avoid floods by burrowing in the stream bed, and the adults, which can take refuge on land. The long-term adult decline wasn’t significantly related to air temperature. Therefore, in this case it seems that the effects of climate change are being felt mainly through higher flood-related mortality in the stream channel rather than increased evaporative water loss among terrestrially-foraging adults.

Reference: Lowe, W.H. 2012. Climate change is linked to long-term decline in a stream salamander. Biological Conservation 145, 48–53.