Growth rates of Corallina officinalis (Rhodophyta) at different temperatures

Specimens of Corallina officinalis L. were grown in the laboratory for 6 and 8 weeks at temperatures of 6°, 12°, 18°, and 25°C. After 6 weeks, the mean growth rates of main axes were 2.8 mm at 18°C, 2.9 mm at 12°C, and 0.2 mm at 5°C; no growth occurred at 25°C. At 6°C, growth increased with lower light intensities. The mean total increase in length of branchlets present when the plants were collected did not vary significantly at 12° and 18°C. At 12°C, axial intergenicula formed in culture produced more new branchlets than did field-grown intergenicula. Also, the production of these branchlets on cultured intergenicula was higher at 12°C than at 18°C.Based on a dissertation completed at Clark University in partial fulfillment of the requirements for a Master of Arts degree by B. J. Colthart.