Balsam fir leaf litter extract stimulates growth of the green snow alga Chloromonas rosae var. psychrophila (Chlorophyta, Volvocales) from Whiteface Mountain, New York

Chloromonas rosae var. psychrophila is the dominant snow alga at Whiteface Mountain, New York, and balsam fir needles often cover the snowbanks in which it lives. Two strains of this snow alga, CU 204 (UTEX SNO 11) and CU 479A (UTEX SNO 56), were isolated from Whiteface Mountain into axenic culture and were grown in balsam fir leaf litter extracts at varying concentrations over a four-week period. Each strain grew better when extract was added to defined modified M-1 medium (control) at all concentrations tested (200:1, 100:1, 50:1, and 25:1; medium:extract) with best growth at 100:1. In strain CU 479A, there was less growth in the highest extract concentration (25:1) when compared to the other concentrations of extracts employed. Both strains showed an increase of growth over a 28-day period when results were pooled for each extract concentration. The results of these experiments suggest that balsam fir leachates stimulate the growth of this snow alga in nature, which may be a selective advantage.