Cold Tolerance and Overwintering of an Introduced New Zealand Frog, the Brown Tree Frog (Litoria ewingii)
Abstract:The overwintering strategy of Litoria ewingii in Otago, New Zealand, was studied under laboratory and field conditions. Microhabitat temperature measurements showed that the frogs were often exposed to subzero temperatures. In the laboratory, L. ewingii tolerated freezing for up to 6 hrs at -1°C, and after the completion of the freezing event (ca. 1 hr) at -2°C. Frogs frozen with insulation survived freezing for 12 hrs at -1°C. Frogs supercooled to -1.2 ± 0.1°C and -1.7 ± 0.3°C on wet and dry substrates respectively. L. ewingii tolerated up to 47.5% of its body water frozen. Plasma glucose levels and osmolality were not increased during freezing. It is concluded that L. ewingii cannot avoid freezing and is sufficiently freeze tolerant to survive the subzero temperatures encountered during winter in Otago.
Document Type: Research Article
Publication date: September 1, 2007
CryoLetters is a bimonthly international journal for low temperature sciences, including cryobiology, cryopreservation or vitrification of cells and tissues, chemical and physical aspects of freezing and drying, and studies involving ecology of cold environments, and cold adaptation
The journal publishes original research reports, authoritative reviews, technical developments and commissioned book reviews of studies of the effects produced by low temperatures on a wide variety of scientific and technical processes, or those involving low temperature techniques in the investigation of physical, chemical, biological and ecological problems.