Seasonal Variability of Phytoplanktons in the Non-Point Source Polluted River Nggada, Maiduguri – Borno State, Nigeria

Abstract

Borno State is the epicenter of Boko Haram crisis which displaced millions of individuals. Maiduguri metropolis which became the principal refuge centre, has witnessed a rapid demographic change, land use and economic activities resulting into intense irrigational practice along the bank of river Nggada. This may result into changes in the physico – chemical parameters of the aquatic ecosystem and the dynamism may disrupt phytoplantonic community. The study was aimed at assessing the seasonal variability of phytoplanktons in non-point source polluted river Nggada of Maiduguri. Water samples for physico -chemical analysis were collected bi-weekly for a period of 11 months at three sampling stations. Physico-chemical parameters, including Dissolve Oxygen (DO), Dissolved Nitrate concentration, Dissolved Phosphorus Concentration, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Surface Water Temperature (SWT) and potential Hydrogen (pH) were determined using standard procedures. Results indicated that all physico – chemical parameters except temperature, DO and pH of the river during both irrigational and non-irrigational regimes were slightly above the National Environmental Standards and Regulations Enforcement Agency’s (NESREA) permissible limits. A total of 7 classes (Cyanophyceae Chlorophyceae, Cryptophyceace, Euglenophyceae, Bacillariophyceae, Crysophyceace and Rhodophyceae) and 16 genera of phytoplanktons were identified.  The results further revealed that the irrigation activities (dry season) have impacted on the physico – chemical parameters (pH, DO, TDS, nitrate and phosphate concentrations) of the study area. Remarkably, the changes in the physico – chemical parameters during the irrigational regime (dry season) have not impacted on the abundance and distribution of phytoplanktons. Hence, the non-point pollutants influenced the physico – chemical parameters of the river butalgal abundance and distribution were not influenced by the changes in the physico – chemical parameters of the river. The study thus, recommends the continuous monitoring and systematic effort to conserve the bio-resources and water quality of the river