The effect of seawater on the metabolism of some seashore and inland mosses.

Photosynthesis and protein synthesis were determined, by measuring uptake and incorporation of radioactive bicarbonate and L-valine, in some seashore and inland mosses after treatment with artificial seawater. In the inland species there was a progressive decline in both processes with increasing seawater concentration. Photosynthesis in the seashore mosses Grimmia maritima and Tortella flavovirens was unaffected by increasing seawater concentration, and supralittoral Ulota phyllantha was less seriously affected than epiphytic material from a subcoastal location. There was a marked decline in chlorophyll content and cessation of photosynthesis in the inland moss G. pulvinata after 3 days' seawater treatment whereas material treated with deionised water showed increased photosynthesis and chlorophyll levels over the same period. In G. maritima both chlorophyll levels and photosynthesis remained relatively unaffected by treatment with seawater for 4 days. Treatment of G. pulvinata with seawater and NaCl led to increased leakage of photosynthetic products to the external solution but this was insufficient to explain the reduction in carbon retained by the plant. The seawater-induced disruption of metabolism in inland bryophytes is believed to be primarily due to the uncontrolled entry of toxic ions into the moss cells whereas seawater tolerance in the seashore species probably reflects the possession of an efficient intracellular cation control mechanism.