[Changes in parameters of Ascophyllum nodosum dark respiration induced by different salinities].

The changes in the rates of O2 consumption and CO2 release by Ascophyllum nodosum thalli in the dark were studied during a 12 day incubation at 34, 20, and 10/1000 salinity as well as at different pH. Depending on the initial pH of the medium, the algae demonstrated antipodal functional responses to the same salinities and, as a consequence, different capacity to overcome hypoosmotic stress. In addition, we observed a more pronounced effect of pH on the rate of O2 consumption than on the rate of CO2 release. Simultaneous desalination and acidification of the medium (pH 7-8) increased O2 consumption in the dark, which activated oxidative processes in the cells and increased their energy status. Forced pH stabilization (8.2) of the medium coupled with its desalination inhibited dark respiration of the algae, which, in our opinion, decreased their energy status. Specific manifestation of hypoosmotic stress and adaptation in A. nodosum are discussed considering the assumed differences in algal energy status.