Impact of Human Activities on the Distribution, Abundance and Diversity of Phytoplankton in the Calabar River System, Cross River State, Nigeria

The impact of human activities on the distribution, abundance and diversity of phytoplankton in the Calabar River System,Cross River State, Nigeria, was investigated for six months (March - August, 2015). Results were pooled for each of theseven stations: Tinapa, Export Free Trade Zone (EFTZ), Nigerian Ports Authority (NPA), Army Base and Nigerian NationalPetroleum Corporation (NNPC) Jetties, including Creek Town Entrance (CTE), where facilities such as recreational,oil, water transport, security, warehouse are located and vessel movements common, unlike Adiabo Bridge Head (ABH)area, which was used as control station, where such facilities are absent. Twenty-nine phytoplankton species belongingto five families (Bacillariophyceae, Cyanophyceae, Pyrophyceae, Chrysophyceae and Chlorophyceae) were recorded.Total of 588 Bacillariophyceae were encountered with 308 Cyanophyceae, 427 Pyrophyceae 286 Chrysophyceae and362 Chlorophyceae. In general, the control station had more phytoplankton with 377 individuals, with 229 individuals atstation 1, 203 at station 2, 243 at station 3, 225 at station 4, 222 at station 5 and 229 at station 6. Phytoplankton speciessuch as Synura among the Chrysophyceae, and Microsterias among the Chlorophyceae were observed to occur at allthe stations, while others were station-specific. Species abundance was observed to vary at each station and ranged from20-25 with 20 at station 5, 21 at stations 3, 4 and 6 and 22 at stations 1 and 2, while the control station had the highestnumber of species with 25 individuals. Margalef’s, Shannon-Wiener and Evenness indices were also observed to varyat each of the stations. These variations are discussed in relation to the impact of human activities on the phytoplanktoncommunity in the river system.