Effect of desiccation on the photosynthesis of seaweeds from the intertidal zone in Honshu, Japan

Abstract

SUMMARY Intertidal seaweeds are periodically exposed during low tide and thus experience extreme levels of desiccation. The physiological activity of seaweeds changes during this water loss process. This study examined how desiccation affects the photosynthesis and respiration of seaweeds from different intertidal levels, and whether the ability to retain photosynthesis and respiration rates during desiccation varies among these species. Photosynthesis and respiration rates of 12 species of seaweeds were measured under various levels of desiccation, using an infrared CO2 gas analyzer. High levels of drought negatively affected photosynthesis, while most species showed initial rises in photosynthetic rates. The ability to retain photosynthesis and respiration activities under desiccation conditions varied among species. These physiological responses were not related to the intertidal level at which these species occur, but to their ability to prevent water loss. The species with lower rates of water loss had slower declines in the rate of photosynthesis and respiration.