GROWTH OF THE FILAMENTOUS GREEN-ALGA CTENOCLADUS-CIRCINNATUS (CHAETOPHORALES, CHLOROPHYCEAE) IN RELATION TO ENVIRONMENTAL SALINITY

Clones of the filamentous green alga Ctenocladus circinnatus Borzi wer e isolated from algae collected at Abert Lake (Oregon) and Mono Lake ( California). Stock cultures were exposed to varied salinities of natur al bake water to examine the effects on growth rate, cell form, chloro phyll a, and water content. Growth rates were reduced in both clones w ith increased salinity over the range 25-100 g.L(-1) and were almost c ompletely inhibited at 150 g.L(-1), Chlorophyll a increased between sa linities of 25 and 100 g.L(-1), reflecting shower growth, higher propo rtions of akinetes, and smaller cell sizes as salinity increased. Tiss ue water content remained essentially constant from 25 to 100 g.L(-1) salinity. Shorter cell dimensions with increased salinity suggest that a lower surface-to-volume ratio may reduce the potential for passive loss of cell water. Prior acclimation of stock cultures to elevated sa linity provided no enhancement of growth response at any salinity. The results indicate that environmental salinity can limit the productivi ty and distribution of Ctenocladus in nature.