Feeding behaviour of Acanthocyclops americanus (Marsh) (Copepoda: Cyclopoida)

Abstract

We evaluated the feeding rates and functional responses of A. americanus using different concentrations and food types of Scenedesmus acutus (Chlorophyceae), Brachionus havanaensis (Rotifera), Moina micrura (Cladocera) and nauplii of A. americanus. The nauplii consumed only algae, thereby competing with cladoceran neonates because their grazing rates of 0.43 × 10⁶ cells h⁻¹ and 0.54 × 10⁶ cells h⁻¹ respectively, are similar. The functional response of A. americanus showed similar rates of consumption of prey nauplii (2.55 ind. h⁻¹) and cladoceran neonates (2.73 ind. h⁻¹). The copepods had a higher preference for the rotifer B. havanaensis regardless of its availability with regard to other tested prey species. Nauplii of A. americanus could be strong competitors of cladoceran neonates since both these crustaceans feed on similar diets while the adult copepods are voracious predators consuming their own nauplii, rotifers and cladocerans. Thus, A. americanus exerts considerable impact on zooplankton communities through different developmental stages.

Keywords:

• Cyclopoids
• functional response
• prey preference
• Rotifera
• Cladocera

Acknowledgements

We thank Dr V. Alekseev and Dr Martha A. Gutiérrez for confirming the copepod identification. CEG thanks Mexican National Council for Science and Technology for a scholarship (CONACyT). We also thank FES-Iztacala and PASPA (UNAM) for financial assistance. Comments made by an anonymous reviewer are gratefully acknowledged.