An epilithic periphyton community showed significant seasonal changes in species composition, abun-dance, and photosynthetic rates in a slow-flowing, manmade stream. Blue green algae were dominant during summer, diatoms were dominant during spring and winter, and green algae dominated the community during fall. The highest photosynthetic rates were found in winter with 24°C as the optimum temperatures for produc-tion in all seasons.
