Competitive interactions between two marine benthic microalgae in mixed culture

Abstract

Experiments were conducted to evaluate the comparative growth responses of two axenic strains of benthic microalgal species in monoculture and mixed culture. In monoculture, <i>Navicula transitans </i> var.<i> derasa </i> had significantly higher cell density (41.6×10³ cells cm^-2 on 18^th day of culture) during the 24-days culture period compared to that of <i>Cylindrotheca closterium </i> (8.9×10³ cells cm^-2 on 15^th day of culture). <i>N. transitans </i> var. <i> derasa</i> was significantly higher in cell density in monoculture than that in mixed culture with <i>C. closterium</i>. In the mixed culture treatments, <i>C. closterium </i> dominated during the first nine days of the culture with a cell density of 5.21×10³ cells cm^-2 and growth rate of 0.50±0.20 μ day^-1. However, from the 12^th day onwards, the cell density of <i>N. transitans </i> var.<i> derasa </i> was significantly higher (4.8×10³ cells cm^-2) compared to that of <i>C. closterium. </i> Latterappeared to be the first colonizer in the culture, whereas the formertook more time to establish itself, but finally out-compete the latter.