THE EFFECT OF CURRENT ON PERIPHYTIC PRODUCTIVITY AS DETERMINED USING CARBON-14

Productivity measurements of organisms attached to artificial substrates ranged from 6.5 to 7.6 mg C/m/sup 2//hr and were 17 to 65 percent greater in stirred bottles (simulated flow) than under static conditions. Carbon-14 was used to determine the effect of current on the primary productivity of these organisms in six artificial streams at the Flowing Streams Laboratory on the Savannah River Plant (U.S. Energy Research and Development Administration, Aiken, South Carolina, U.S.A.). Seasonal changes in dominant organisms were monitored from June 1973 to March 1974. Estimates of productivity, accumulated biomass, and levels of chlorophyll ..cap alpha.. were compared for possible correlation. Production of chlorophyll ..cap alpha.. ranged from 50 to 381 mg/m/sup 2/, and accumulated biomass ranged from 45 to 181 g/m/sup 2/ on the artificial substrates (glass microscope slides) during the period of study. Productivity of attached organisms was generally an order of magnitude greater than productivity of phytoplankton or tychoplankton. The consistently higher productivity in simulated flowing systems than in static systems tends to cast some doubt on values obtained when lotic communities have been enclosed or isolated in chambers or bottles wthout inducing a current or stirring action.