Competitive outcome between the rotifer brachionus calyciflorus and the cladoceran moina macrocopa depends on algal density but not temperature

Abstract

The rotifer Brachionus calyciflorus often occurs simultaneously with the cladoceran Moina macrocopa in tropical water bodies. We studied the effects of temperature (20, 25 and 30 C) and algal density (0.5, 1.0 and 3.0×10 6 cells.mL-1 Scenedesmus obliquus) on the outcome of competition and duration of coexistence between B. calyciflorus and M. macrocopa using population growth experiments. The results showed that regardless of temperature, M. macrocopa outcompeted B. calyciflorus at the lowest algal density (0.5×106 cells.mL-1), whereas B. calyciflorus outcompeted M. macrocopa at the higher algal densities (1.0 and 3.0×106 cells.mL-1). The duration of coexistence shortened with increasing temperature when M. macrocopa outcompeted B. calyciflorus, and those with increasing temperature and algal density when B. calyciflorus outcompeted M. macrocopa. Our results suggested that the competitive outcome between the rotifer B. calyciflorus and the cladoceran M. macrocopa was dependent on algal density but not temperature, the duration of coexistence between them was dependent on algal density and temperature, and the exploitative competition of M. macrocopa over B. calyciflorus may be more important than the interference competition. © 2014 EDP Sciences.