THE CONTROL OF CATION LEVELS IN SEASHORE AND INLAND MOSSES

Abstract

After immersion of seashore and inland mosses in artificial seawater, their extracellular, exchangeable and intracellular cations were analysed. Levels of extracellular and exchangeable Na and Mg in both inland and seashore mosses increase. In the intracellular fraction of inland species there was a rapid loss of K and an accompanying net uptake of Na by a slower, possibly active, process. K loss from inland mosses occurred in seawater concentrations exceeding 50% whereas seashore species withstood concentrations of seawater up to 200% with little change. Treatment of the seashore moss, Grimmia maritima, with NaCl at the concentration in seawater produced almost complete loss of intracellular K. This effect was greatly alleviated by Ca, partially by Mg and was nullified when Na was accompanied by both Ca and K. When Grimmia spp. were supplied with seawater solutions containing a range of Ca concentrations, G. pulvinata showed stimulation of net uptake of Na and reduced net loss of K with increasing Ca concentration whereas G. maritima showed inhibition of net uptake of Na and increased net uptake of K. The ability of seashore mosses to withstand immersion in seawater without undergoing large changes in intracellular cation content may reflect greater K specificity of the monovalent cation uptake carriers than in the inland species studied. Copyright © 1974, Wiley Blackwell. All rights reserved