Species-specific responses of Antarctic terrestrial microalgae to salinity stress. Comparative study in <i>Klebsormidium</i> sp. and <i>Stigeoclonium</i> sp.

We studied the changes in PSII photochemical processes in the cells of Antarctic algae Klebsormidium sp. and Stigeoclonium sp. exposed to salinity stress (0 - 3M NaCl) for 3 h. Salinity stress induced a decrease in the potential (FV/FM) and effective quantum yield of PSII electron transport (PSII). Salinity stress induced a decrease in vitality index (Rfd, relative decrease of chlorophyll fluorescence). Analyses of the polyphasic fast chlorophyll fluorescence transients (OJIP) showed that with the increase in salt concentration, the chlorophyll fluorescence signals recorded at the phases J, I, and P declined, and the transient flattened with increaseing NaCl concentration reaching close to zero ChlF values at salt concentration of 3 M NaCl after 180 min. exposition. Klebsormidium sp. was found more salinity stress resistant than Stigeoclonium sp.