Abstract/Summary:
Only a few notes about the abiotic factors, flora and fauna have been published on the warmest spring of Disko, Puilassoq in Mellemfjord/ Akugdlit. The spring was first described by Steenstrup in 1900, but has since been visited several times by biologists, most recently by the Danish-German Excursion 1998. The chemistry of the water, and the flora and fauna of the spring are here described for the first time. The spring consists of six outflows located on a nearly 2 m high dome, the warmest outflow being about 18°C. pH is 10.0-10.8 and conductivity 100 µmho or less. About 60 species of vascular plants are present within a distance of 2 m from the never freezing water, a high number for a plant community at this northern latitude. The richness of the species is considered related to raised soil temperature, increased mineralization and decomposition, and a prolonged growing season caused by the activity of the spring. The fauna includes many species of Rotifera, 21 species of Tardigrada, four species of Oligochaeta, two species of Trichoptera, Arachnida, the beetle Hydroporus morio, and the fly Scatella thermarum.