A SIMPLE-MODEL FOR ESTIMATING THE ICE CONTENT OF FREEZING ECTOTHERMS

1. 1.Although body ice content is an important variable affecting freeze tolerance, present calorimetric methods for its measurement necessarily require the termination of a freezing protocol. 2. 2.A simple iterative model, based on the colligative properties of solutions and requiring precise measurements of only equilibrium freezing point (of the unfrozen organism) and of core body temperature, allows estimation of the percentage of body water frozen at any time during a freezing episode. 3. 3.This model can also predict the lethal temperature for a freezing ectotherm, assuming that death occurs due to osmotic dehydration when 67% (of any other known lethal fraction) of the body water is frozen. 4. 4.The basic model is easily extended to evaluate the effects of variables such as: body mass, initial body water content, initial osmotic concentration, and test chamber microenvironment. 5. 5.This model is not intended to supplant existing more exact biophysical models of freezing kinetics. Rather it is proposed as a first approximation which is generally supported by published data and which should be of significant practical value for investigators of freeze tolerant organisms. © 1990.