Evidence does not support the conclusion that Hexarthra intermedia (Rotifera, Monogononta, Flosculariaceae) causes mortality in Bosmina longirostris (Cladocera, Diplostraca, Branchiopoda)

Abstract

Evidence does not support the conclusion that Hexarthra intermedia (Rotifera, Monogononta, Flosculariaceae) causes mortality in Bosmina longirostris (Cladocera, Diplostraca, Branchiopoda)Based on observations of preserved samples, Jaramillo-Londoño & Pinto-Coelho (2010) describe a putative ecological relationship between the rotifer Hexarthra intermedia and the cladoceran Bosmina longirostris as a fusion of parasitism and interference competition. They argue that H. intermedia enter the filtering chamber of B. longirostris allowing the rotifer to exploit food collected by Bosmina, while simultaneously receiving protection from predators. In addition, they surmise that the result of this interaction can lead to death of Bosmina. We posit two simpler explanations for their observations. (1) Presence of H. intermedia in the cladoceran's filtering chamber is an artifact of the collection methods. (2) Statistical correlations between the population levels of these two species simply means that the environment was suitable for their growth. Thus until additional evidence corroborates their findings, the simpler explanations should prevail.