The Influence of Salinity on the Rate of Dark Respiration and Structure of the Cells of Brown Algae Thalli from the Barents Sea Littoral

We studied the changes in the rate of dark respiration (DR) and structure of the cells in Ascophyllum nodosum and Fucus vesiculosus thalli during the incubation at 40, 34, 20, 10, and 2 salinity for 14 days. The changes in salinity affected the rate of DR and the structure of the thallus apical cells: the organelles swollen and were destroyed later. The effect of hyposalinity on the algae was more pronounced as compared to hypersalinity. The stress intensity directly increased with the degree of desalination. Further adaptation of the algae to low salinity enhanced DR and, hence, was an energy-dependent process. Despite higher DR rates (during the stress and adaptation) in F. vesiculosus as compared to A. nodosum, the seaweeds had similar pattern of adaptation to the variation of salinity. Different primary response of the seaweeds to 20 salinity was an important exception; apparently, the salinity around 20 is the limit of these species distribution in desalination zones.