Comparative trophic ecology of two sympatric tilapia, Oreochromis niloticus (Linné, 1758) and Sarotherodon melanotheron (Rüppell, 1852) from Lake Toho, Southern Benin: Food competition and risk of species replacement

Abstract

Knowledge on trophic ecology of coexisting invasive and native fishes is of great importance for fisheries management, species conservation, and ecosystem integrity. We investigated the feeding ecology of two tilapias, Oreochromis niloticus, exotic and invasive, and Sarotherodon melanotheron, native, in order to explore diet similarities and food competition between these two cichlids of Lake Toho (Southern Benin). Fish individuals were sampled bimonthly from May-December 2013 in all habitats. Sarotherodon melanotheron consumed about 107 food resources dominated by algae (86.88%) and detritus (7.87%). Likewise, O. niloticus ingested about 65 food resources dominated by algae (62.75%) and detritus (33.40%). Sarotherodon melanotheron exhibited a higher diet breadth (DB = 15.23), and the high diet similarity index (Ojk=0.83) recorded indicated a high competition between the two cichlids. Further research on species behavior, hybridization and food competition are required to assess risks of native species replacement and the overall impacts of O. niloticus invasion.