Effects of salinity on growth of Baltic and Atlantic<i>Fucus vesiculosus</i>

Abstract

Vegetative apices of intertidal Atlantic and permanently sublittoral, brackish water, Baltic Fucus vesiculosus were cultured in a salinity range (1·5–45 ppt) in the laboratory. Tank experiments with running Baltic sea-water were also conducted under summer (10–20°C) and autumn (7–10°C) temperature ranges. Both populations were able to grow in a wide range of salinity in laboratory culture. The Atlantic population showed better growth in higher salinities and virtually no growth in 1·5 ppt, in which it died after 7 weeks. In contrast the Baltic plants grew better in the lower range of salinity. Baltic material took nearly 4 weeks to recover from upshock in salinities 34 and 45 ppt, and showed 10–15% loss of tissue weight during the first two weeks. Growth then started, but in the highest salinity (45 ppt) growth was negligible. When cultured in a semi-natural Baltic environment, in a tank experiment, Atlantic plants could not survive whereas Baltic plants showed vigorous growth. The combination of continuous submergence, low salinity and changing temperatures may have caused apical meristem necrosis and the death of Atlantic Fucus vesiculosus in both summer and autumn tank experiments.