Spring salamander (Gyrinophilus porphyriticus) COSEWIC assessment and status report: chapter 9

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Limiting Factors

Habitat modification is the major threat to the species. Sedimentation related to stream bed and shore bank alteration during road construction and canalization work affects survival of salamander larvae (Bury 1980). The transformation of hydrographic systems has affected the survival of G. porphyriticus in New Jersey and Mississippi (Ashton 1976). Pumping of aquifers near springs also affects the survival of stream salamanders. In fact, water pumping in residential areas can modify a water regime from permanent to temporary (Medina 1990).

Changes in stream conditions following the elimination of forest at the stream edge also affects the survival of salamanders (Bury 1980; Corn and Bury 1989). Though the effect of forest cutting on aquatic habitats may be temporary (Martin et al. 1984; Likens 1985) it may have long term effects on genetic diversity and survival of salamander populations (Stiven and Bruce 1988).

The impact of atmospheric pollutants or pesticides used in forestry and agriculture (especially in orchards) is not documented (Harfenist et al. 1989). However, G. porphyriticus may be vulnerable to contamination due to its high trophic level and its longevity. Bury (1980) mentions that pollution of underground water and runoff of contaminants into streams can affect the survival of stream salamanders.

Predatory fish limit the survival of spring salamander larvae (Resetarits 1991 and 1995). The introduction of trout into headwater streams and ponds might therefore affect salamander populations.

Beavers modify stream conditions by the construction of dams, causing the warming of the water and eutrophication of the aquatic habitat. This affects mainly streams in lowland and foothill regions since beavers usually avoid mountain streams because spring floods affect water level variation (Banfield 1975). Although the impact of beaver activities may be restricted to marginal downstream populations, it could become significant if the beaver populations increase following reduction of beaver trapping, reduction of the beaver's natural predators, and increase in the beaver's food resources due to forestry practices favoring second growth tree species.