Reproduction of the Siberian salamander, Salamandrella keyserlingii (Amphibia, Caudata, Hynobiidae), in water bodies on permafrost in Northeastern Asia

Abstract

The possibility for Siberian salamanders to reproduce in the permafrost zone of Eurasia is due to specific thermal conditions in small water bodies (pools) freezing to the bottom, rather than to the adaptive properties of the species. These conditions are as follows: (1) meltwater in freezing marshland pools appears relatively early; (2) the rate of water warming increases in the south-north direction due to the lengthening of the daylight period; (3) water temperature is higher than air temperature but does not reach the values critical for S. keyserlingii eggs and larvae; and (4) the thawed silt layer prevents water cooling by the underlying permafrost bed. Reproduction of Siberian salamanders in different parts of the species range begins under similar thermal conditions, which are formed 1.5–2 months earlier in the south (the Jewish Autonomous Region) than in the north (the Chaun Bay coast). In any region, the onset of spawning may vary by up to 30 days. The existence of Siberian salamanders in the tundra zone is facilitated by continuous daylight during the polar day, which provides for rapid water warming to relatively high temperatures and creates additional opportunities for larval feeding. These factors may account for the acceleration of amphibian ontogeny in the North, noted by Shvarts and Ishchenko (1971). The northern boundary of the Siberian salamander range in Eastern Siberia is defined by the sum of water temperatures over the warm season, which should be no less than 850–900°/day. This boundary in the tundras of Europe, Western Siberia, and the Chukchi Peninsula is shifted southward, with its location being apparently dependent on some other factors.