AB prepress abstract  -  DOI: https://doi.org/10.3354/ab00713

Effects of common carp and African catfish on plankton, periphyton, benthic macroinvertebrates in pond ecosystem

E. R. Chirwa*, A. Mtethiwa, W. L. Jere, D. Kassam

*Email: erchirwa@gmail.com

ABSTRACT: As the common carp (Cyprinus carpio) and African catfish (Clarias gariepinus) affect biotic assemblages in aquatic ecosystems through their benthivory, their introductions have been considered an environmental concern. The aim of this study was to compare the effects of common carp and African catfish on adjacent trophic level assemblages of plankton, periphyton and benthic macroinvertebrates in a pond ecosystem. The study was conducted at the National Aquaculture Center, Zomba, Malawi. Four treatments were involved in the study: ponds with common carp (T1), ponds with African catfish (T2), ponds with both common carp and African catfish (T3), and ponds lacking both common carp and African catfish (T4). Results showed that T1 had the most abundant phytoplankton but the least periphyton, zooplankton and benthic macroinvertebrate abundance and diversity. T4 had the least phytoplankton but the most abundant and diverse zooplankton, periphyton and benthic macroinvertebrates. There was no significant difference (p > 0.05) between T2 and T3 in terms of phytoplankton, periphyton and benthic macroinvertebrate abundance and diversity, which were intermediate between T1 and T4 ponds. Better water quality regime and increased biomass of native tilapia fish were also observed in T3 ponds. It is concluded that the farming of common carp in aquatic ecosystems containing the African catfish may not adversely affect the environment and that the polyculture of the African catfish and common carp can be adopted as a management strategy to mitigate the potential adverse effects of common carp.