Physicochemical parameters and plankton diversity from Lower River Benue, Makurdi

This study was conducted to investigate the abundance and diversity of plankton as well as the physicochemical properties of the Lower Benue River. The survey was carried out at different sites along the river both at Wadata and BSU Water Board. Samples were collected using plankton net into bottles preserved in 5% formalin and then transported to the laboratory for identification, counting and further analysis. A total of 39 plankton were observed out of which 28 (71.79%) were obtained at Wadata and 11 (28.21%) at BSU Water Board. The most abundant of all the species was Arthrospira plantensis which was observed 16 times. The least occurring plankton was the Paramecium species which was observed only once. The species richness at the Wadata location was 7 with a Shannon-Weinner Diversity Index of 1.383 and Evenness of 0.711. The species richness at the BSU Water Board on the other hand was 3 species with the Shannon-Weinner Diversity Index (H) of 0.935 and an Evenness of 0.851. A significant relationship between plankton abundance and sampling location was overserved (χ2 = 19.360; df = 1; p = 0.000). The Physicochemical properties of the Lower Benue River at the respective sampling locations revealed that air, water temperature and dissolved oxygen, had no significant difference observed between them (p>0.05). While pH of the water, electrical conductivity, turbidity and total dissolved solid had significant differences observed between them (p>0.05). A fairly strong non-significant positive relationship was observed between plankton abundance and the pH (r = 0.502; p = 0.389). Electrical conductivity (r = 0.629; p = 0.069) and total dissolved solid (r = 0.461; p = 0.298). On the other hand, a very strong non-significant negative relationship between plankton abundance and air temperature was observed (r = 0.819; p = 0.090). The relationship with turbidity was also negative and strong but they were significantly associated (r = 0.720; p = 0.029). Pearson’s correlation coefficient (r) further revealed a very weak non-significant relationship between plankton abundance and dissolved oxygen (r = 0.137; p = 0.747), while it showed no significant relationship with temperature (r = 0.047; p = 0.904).