The Ability of Porphyra linearis (Rhodophyta) to Tolerate Prolonged Periods of Desiccation

Abstract

Porphyra lineraris, is the uppermost intertidal macroalga on the eastern Mediterranean coast. It is able to regain photosynthetic activity upon reimmersion, even after drying in air to a stable water content of ca. 5% of fully hydrated plants for a period of three weeks. During desiccation experiments the plants continued net emersed photosynthesis at a maximal rate until their relative water content (RWC) dropped to 60%. Net photosynthetic gas exchange of plants with only 10% RWC was still positive. Photosynthetic rates, however, decreased during the drying process more rapidly than did the respiration rates. During rehydration, plants previously kept dry (5% RWC) for short periods (up to 24 h) regained net photosynthetic capability only when their RWC reached about 35%