ANTITHAMNIONELLA-FLOCCOSA (RHODOPHYTA) IN CULTURE - DISTRIBUTION, LIFE-HISTORY AND CHROMOSOME-NUMBER

Antithamnionella floccosa from Norway was grown under different combinations of temperature and salinity, and a Polysiphonia type of life history was demonstrated for the first time in culture. The alga survived temperatures from -1-degree-C to 15-degrees-C and salinities from 18 parts per thousand to 32 parts per thousand. The life cycle was completed in 8 months at 8-degrees-C under a 16:8 light:dark cycle, but not under continuous light at the same temperature. At 14-degrees-C and with a 16:8 light:dark cycle, gametangia were produced, but no carposporophyte development occurred. The results suggest that the southeastern boundary of distribution in Scotland and southern Norway is set by a lethal summer temperature of 17-degrees-C. The northern distribution limit is probably a reproduction limit near a summer maximum of 6-degrees-C, or due to unfavourable ice and light conditions during winter. Distribution data from the western Atlantic coast indicate a broader temperature tolerance than on European coasts. This might be explained in terms of ecotypic differentiation. A haploid chromosome number of n = 31 - 33 was determined in apical cells of gametophytes.