Some aspects of limnology on a stretch of the lower Benue river, Makurdi, Benue state, Nigeria

Abstract

The study investigated the physicochemical parameters, abundance and diversity of plankton community index of the lower Benue River. The physicochemical parameters encountered in this study include DO, BOD, pH, Alkalinity, Hardness, Phosphorous, Air temperature, Water temperature, Co2, Chloride, Nitrate, TDS and Transparency. This study shows significant differences in physic-chemical properties of all parameters determined in the three sample sites. It was also observed that physico-chemical parameters affect distribution, occurrence and diversity of the plankton. Eighteen species of five families of phytoplankton were identified ranging from six species of Bacilliarophyceae, five species of Chlorophyceae, three species of Cyanophyceae, two species of Chrysophyceae and two species of Euglenophyceae. Also 14 species of four families of zooplankton were identified during the study period ranging from three species of Copepoda, four species of Monogononta, three species of Branchiopoda and four species of Insecta. It was observed that some sensitive species of plankton were low in abundance at some sampling sites due to gradual disappearance as the water becomes polluted while other tolerant ones survived the pollution stress and relocated to downstream off the point of discharge. Therefore, the lower Benue River is a rich ecological ecosystem with high plankton diversity that can sustain fishery development.