Influence of Reduced Salinity on the Distribution of Two Laminarian Algae

Abstract

Two species of marine algae, Chorda filum and Saccorhiza polyschides were cultured in the laboratory in a wide range of salinities from the full salinity of sea water down to that of fresh water. Both species were found to develop from spores at a progressively slower rate at lower salinities. The development of S. polyschides was irreversibly inhibited at salinities below 9 %o whereas C. filum was able to produce sporophytes at salinities as low as 5 %0. The narrow tolerance of S. polyschides to reduced salinity was correlated with the absence of this species from areas of reduced salinity in nature. The tolerance of C. filum to low salinity agreed remarkably well with the distribution of this species in the Baltic Sea. The wide salinity tolerance exhibited by British plants of C. filum suggests that it is unlikely that the plants growing at the limits of the range of this species in the Baltic Sea are a different physiological strain specially adapted to the extreme environmental conditions prevailing there. PeBXoMe