Physiological responses to salt stress by native and introduced red algae in New Zealand

Intertidal macroalgae are regularly exposed to hypo- or hypersaline conditions which stressful. However, red algae in New Zealand generally poorly studied terms of salinity tolerance. Consequently, two native (Bostrychia arbuscula W. H. Harvey [Ceramiales], Champia novae-zelandiae [J. D. Hooker & Harvey] [Rhodymeniales]) and one introduced algal taxon (Schizymenia spp. J. Agardh [Nemastomatales]) were for 5 days a controlled salt stress experiment investigate photosynthetic activity osmotic acclimation. The B. was not affected by salinity, as reflected an almost unchanged maximum quantum yield (Fv/Fm). In contrast, the Fv/Fm C. Schizymenia strongly decreased under conditions. Treatment with different salinities led increase total organic osmolyte concentrations rising highest recorded at SA 38, followed declining amounts further exposure. arbuscula, sorbitol main osmolyte, while other taxa contained floridoside. data presented indicate that all three species conspicuously differ their upper intertidal exhibited wide tolerance unaffected parameters strong accumulation increasing salinities, hence can be characterized euryhaline. novae-zelandiae, preferentially occur mid-intertidal, showed narrower species-specific responses reflect respective vertical positions zone. Key words: floridoside; hypersaline; yield; osmolytes;