The cellular ability of desiccation tolerance in Japanese intertidal seaweeds

Photosynthetic activities of submerged seaweeds before and after drying were measured in eighteen species collected from different vertical positions from a Pacific shore at Shimoda City in Japan. The seaweeds were desiccated until the cellular water levels equilibrated with the air in the chamber under various humidities at 10 degreesC. Relative water contents of all species drastically decreased as the cellular water potentials were reduced from 0 to -14MPa and gradually decreased in the range from -14 to -158MPa. Porphyra dentata, which is an upper intertidal species, recovered photosynthetic activity from the lowermost water potential of -158MPa, while the plants collected from the lower intertidal and subtidal zones reduced their photosynthetic activities after desiccation to comparatively higher water potentials from 0 to -14MPa. Other species collected from the middle intertidal zone reduced their photosynthetic activities following desiccation to water potentials in the range from -14 to -158MPa. It is concluded that the cellular abilities of desiccation tolerance in intertidal seaweeds varied between the species examined and correlated with their vertical position within the tidal zone.