Algae. 1989; 4(2): 143-147.
The Influence of Temperature Shift on the Photosynthesis of Two Marine Macrobenthic Algae, Cladophora densa and C. opaca
Nobuyasu Katayama, Munekatsu saitoh
Department of Biology, Tokyo Gakugei University. Department of Food and Nutrition, Seikatsu Gakuen Junior College, Mitake
Cladophora densa Harvey and C. opaca Sakai, were collected from the intertidal zone of Otsuchi Bay, Iwate Prefecture, Japan, in June, 1986 and in August, 1989. The influence of a stepwise temperature rise on the rate of photosynthesis in both algae was examined. In both species collected in June, the rate of apparent photosynthesis increased as the temperature rose up to 25℃ and decreased thereafter at higher temperatures until completely stopping at 35℃. In the samples collected in August, however, the influence of temperature shift on the rate of apparent photosynthesis was different between the two species. In C. densa the rate of apparent photosynthesis increased up to 25℃, and thereafter decreased as the temperature rose. The photosynthetic activity was almost completely lost at 35℃. In C. opaca the rate increased with the temperature up to 30℃ then decreased but the activity still continued at temperatures higher than 40℃ although at a low level. C. opaca grows at the middle intertidal zone while C. densa does at around the low water mark. The former must have abilities somehow to tolerate the water loss and high temperature. The present result indicates that in summer C. opaca adapts to severe temperature conditions at which C. densa cannot grow.
Keywords : Chlorophyceae, Cladophora, Photosynthesis, temperature effect, vertical distribution