Species control of microalgae in an aquaculture pond

Abstract

To effectively control and maintain microalgal species in an aquaculture pond is necessary because microalgae play an important role in stabilizing pond water quality via either ammonia uptake or oxygen production. In this study, microalgae taken from a tilapia rearing pond were cultured, under various temperatures and ammonia-N concentrations, by using both continuous-flow and batch reactors. The succession of dominant microalgal species was examined. The dominant microalgae species in batch reactors are Chlorella vulgaris, Scenedesmus ellipsoideus, S. dimorphus and Westella botryoides under the conditions of dilution rate, 0.25 day−1; temperature, ranging from 17 to 32°C; ammonia-N concentration, less than 15 mg/l and light intensity, 4000 lux. The dominant species found in batch reactors are more stable than those found in continuous-flow reactors. Low concentrations of both ammonia-N and microalgae are desirable for obtaining a better control of dissolved oxygen level in an aquaculture pond.