A comparison of the water quality and plankton diversity of the Okamini Stream to the freshwater systems within the New Calabar River catchment, Port Harcourt, Nigeria

Abstract

The water quality and phytoplankton diversity of the Okamini Stream, Port Harcourt, Nigeria was studied between April and June 2018 at three stations. The data was used to assess the health of the system for supporting local communities. Compared to national and international standards, the stream was found to be acidic, but pH levels (5.87 ± 0.40) were similar to other systems in the New Calabar River catchment. Analysis of variance showed that there was no significant variation (p < 0.05) in water quality between the stations, with the exception of PO₄ (0.82 ± 0.40 mg l^-1), which was significantly higher than other local systems. A total of 26 species of plankton were recorded during the study. These species belonged to the Bacillariophyceae (n = 10), Chlorophyceae (n = 6), Cyanophyceae (n = 5), Euglenoidea (n = 3), and Chrysophyceae (n = 2), but phytoplankton density was low. The most frequently occurring phytoplankton species were indicators of organic pollution, such as Cyclotella comta, while Melosira varians was recorded at all sampling occasions. Relatively high diversity indices indicated a stable environment. We conclude that the Okamini Stream is not yet degraded, but that the water quality should be monitored, and anthropogenic activities managed to avoid potential future deterioration.

Keywords:

• acidification
• eutrophication
• Niger Delta
• physico-chemical characteristics
• river health