Ecology and Diversity of Zooplankton in the Great Kwa River, Cross River State, Nigeria

Ecology and diversity of zooplankton in the Great Kwa River, located in Cross River state (Southern Nigeria) was studied based on bi-monthly samples collected for six months (May to October, 2012). The objective of the study was to determine the abundance and species composition of zooplankton from four sampling stations in the study area. A total of forty-four (44) taxa belonging to seven (7) taxonomic groups were recorded: 1 Heterodonta and Salpid (2.27 %), 2 Chaetognathans and Decapods (4.55 %), 7 Rotifera (15.91 %), 11 Cladocera (25.0 %) and 20 Copepods (45.45 %). Total number of species in relation to sampling stations was highest in Esuk Atu with 34 species (27.2 %), followed by 33 species in Anantigha station (26.45), followed by 32 species in Obufa Esuk station (25.6 %) and lowest in Abitu station with 26 species (20.8 %). Absolutely constant species (AS) were found only in Cladocera (Daphnia magna, Daphnia pulex and Daphnia rosea) and Copepoda (Calanus calanus, Calanus fimnarchicus, Diaptomus gracilus, Enterpira autifrons, Enterpira elongatus, Paracalanus parvus and Pseudocalanus elongatus). Based on these findings, it could be concluded that the relatively high zooplankton species diversity in the Great Kwa River is an indication of the healthy state of the river.