THE EFFECT OF SMALL-SCALE FLUID MOTION ON THE GREEN-ALGA SCENEDESMUS-QUADRICAUDA

The effect of shear flow on the green alga Scenedesmus quadricauda gro wn in Bristol's medium was tested. The shear flow was generated using a Couette type rotating cylinder apparatus. Growth of Scenedesmus quad ricauda, measured in terms of chlorophyll a concentration, was inhibit ed under different fluid motions. Inhibition was most pronounced at hi gh Reynolds number (Re) and the corresponding mean rate of energy diss ipation (epsilon). Algal growth was maximum during the stagnant fluid flow experiment. The flocs comprised of dead and living cells of algae formed as a result of shear flow. Cell morphometry did not change con sistently under different flow conditions but cell destruction was evi dent. A two step model is proposed, relating algal growth as a functio n of Re, and epsilon. The attenuation factor, phi(F) for growth limiti ng conditions under different fluid motions, was defined as the ratio of the algal growth rate constant to the maximum algal growth constant under stagnant fluid flow conditions.