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

¹ College of Life Sciences, Anhui Normal University, Provincial Key Laboratories of Conservation and Utilization for Important Biological Resource in Anhui & Biotic Environment and Ecological Safety, Wuhu, Anhui 241000, China
² College of Biological and Pharmaceutical Engineering, West Anhui University, Lu'an, Anhui 237012, China

^* Corresponding author: ylxi1965@126.com

Received: 15 September 2013
Accepted: 22 January 2014

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 3.0×10⁶ 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.