Abstract: | The effects of hypo- and hypersaline treatments ranging from768% on the intracellular inorganic ion and organic soluteconcentrations were determined in the eulittoral green macroalgaeUlothrix implexa, Ulothrix subflaccida, Enteromorpha bulbosa,Acrosiphonia arcta, and Ulva rigida from Antarctica and SouthernChile. The main inorganic cations were K+, Na+, and Mg2+ inall species. The major osmolyte in E. bulbosa, A. arcta, andU. rigida was K+ at increasing salinities. In both Ulothrixspecies, however, K+ levels declined during hypersaline stressand Na+ concentrations rose significantly. The main inorganicanions were Cl-, SO24-, and PO34- in all algae, while E. bulbosaand U. rigida also contained NO+3. A. arcta showed an extremelyhigh SO2-4 content. The organic solutes proline, sucrose, andß-dimethylsulphoniopropionate (DMSP) played an importantrole in osmotic acclimation. The occurrence of three organicosmolytes suggests an additional function of these solutes ascryoprotectants in the cold-water macroalgae investigated. |