Low temperature tolerance of the gemmules of Eunapius fragilis

This present study has shown that hydrated gemmules of Eunapius fragilis (Leidy) are able to survive brief exposure to temperatures as low as −100°C. However, the rates at which the gemmules are cooled and warmed have a marked effect on their survival. Hydrated gemmules exhibited good survival when cooled to −30°C at 0.1°C/min or 0.5°C/min. On the other hand, gemmules cooled at 1.0°C/min or 10.0°C/min did not survive. The effect of warming rate on the survival of gemmules exposed to −30°C was less pronounced than that of the cooling rate. However, gemmules which were warmed very slowly (0.1°C/min) showed a low level of germination. Hydrated gemmules also survived exposure to −72°C for at least 30 days. It appears that the time of exposure to low temperature is far less important in determining survival than the rates at which the gemmules are cooled to such low temperatures and then subsequently warmed.