EFFECT OF LIGHT, TEMPERATURE AND PH ON PHOTOSYNTHESIS IN A FILAMENTOUS RED ALGA (CERAMIACEAE, RHODOPHYTA)

Exposure of Ceramiaceae indet., an undescribed filamentous red alga, t o an irradiance of 819 mu mol m(-2) s(-1) for various lengths of time (up to 120 min) had no effect on its photosynthetic performance. Expos ure to 3 114 mu mol m(-2) s(-1) for 30 min or longer caused a signific ant decrease in its photosynthetic capacity. Compared to the responses of other species, Ceramiaceae indet. appears to be able to tolerate f ar higher levels of irradiance than most species. Ceramiaceae indet. w as able to slowly acclimatize (over 7 days) to temperature changes wit hin the range tested (15-25 degrees C). Rapid 5 degrees C increases in temperature within this range increased photosynthetic performance, a s indicated by an increase in P-max. However, a rapid increase or decr ease of 10 degrees C significantly reduced photosynthesis. Ceramiaceae indet. displayed pH-sensitive photosynthesis, with an increase in pho tosynthesis in acidic conditions.