UNIALGAL CULTURES OF CLADOPHORA GLOMERATA (L.) KÜTZ.(1) (2) : I. RESPONSE TO TEMPERATURE.

Unialgal cultures of Cladophora glomerata (L.) Kütz. grew with increasing vigor at temperatures between 15 and 30 C. Vegetative cells were killed upon freezing or when exposed to temperatures above 30 C. No growth occurred at 5 C and only slight growth was observed at 10 C. Effects of near lethal temperature on C. glomerata were dependent upon the duration of exposure in addition to the actual temperature attained. The response of this alga to various temperatures under culture conditions is in accord with tolerance limits established for naturally occurring populations. It seems probable that the annual periodicity of C. glomerata is regulated in large measure by seasonal variations in water temperature, greatest abundance coinciding with water temperatures between 15 and 30 C.