Electrical Impedance in Ascophyllum Nodosum and Fucus Vestculosus in Relation to Cooling, Freezing, and Desiccation¹

SUMMARY Electrical impedance monitoring techniques appear to be useful in tracing the effect of cooling or desiccation upon the thallus of Fucus vesiculosus and Ascophyllum nodosum . These algae were found to be remarkably resistant to injury from freezing down to −20 C even during midsummer and from desiccation up to 70% water loss, and in these properties were markedly different from land plants. Freezing point depressions, the degree of supercooling, activation energies of cooling‐impedance curves, and the slope of these curves themselves were useful in disclosing differences between time of sampling, storage time, and indications of damage in tissue. No significant difference could be detected between the 2 species collected and tested at the same time. Significant differences occurred in F. vesiculosus between summer and winter, and in winter between submersed and intermittently exposed plants. Tracer ion uptake techniques confirmed that freezing to −20 C did not kill tissues.