ICE NUCLEATION IN SEAWEEDS IN RELATION TO VERTICAL ZONATION

The ice nucleation temperatures of thallus fragments of different macr oalgal species were investigated. The samples were collected fi om the littoral zone on a rocky shore in Trondheimsfjord, central Norway. Th allus fragments of species growing in the zipper parts of the eulittor al zone had lower ice nucleation temperatures than those of species li ving in the lower eulittoral zone and in. the upper sublittoral zone. Samples collected in the winter had lower nucleation temperatures than samples from the same species collected in the summer, which indicate s that the seaweeds are removing or inactivating ice nucleators as a p art of their cold hardiness strategy.