The Amphibian Decline in Norway – Reasons and Remedy (Case: Acidic Precipitation)

D. Dolmen


Earlier studies indicate, but do not prove, that amphibian declines in Scandinavia in part are due to anthropogenic acidification. For instance, amphibians are very rare in the acidified region of Southern Norway. In this study, a total of 58 lakelets (pH range: <4.4 – 6.9; mean ± S.D.: 5.0 ± 0.5) were investigated in 1996 and 1997. Only a very few amphibian sites were registered. In early springs 1998 – 2001, liming was then carried out in 4 of the lakelets that lacked amphibians, but lay within reasonable migration distance. They were all strongly acidified before liming (pH in spring 1997: 4.7 ± 0.1). The pH values rose (1998: 5.1 ± 0.2, 1999: 5.5 ± 0.8, 2000: 6.1 ± 0.4, and 2001: 6.5 ± 0.6). All four years, amphibians of all three species for the region (Rana temporaria, Bufo bufo, Triturus vulgaris) started to show up, and two of them were spawning in increasing numbers. Conclusions: Acidification is the main reason for an amphibian decline in Southern Norway — and liming of lakes is a remedy.


amphibian decline; Rana temporaria; Bufo bufo; Triturus vulgaris; acidification; liming; Norway

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