Effect of Selected Water Quality Properties on the Occurrence and Distribution of Aquatic Macrophytes in the Floodplains of River Benue at Makurdi

A study was carried out in River Benue and 10 sites constituting the floodplains of River Benue to determine the effects of selected water quality parameters on the incidence and infestations of aquatic macrophytes. All water quality properties were analyzed using Standard Procedures. Water pH was observed to be variable, ranging from 5.7 at River Benue at the point at which effluents from BBL are discharged to 7.8 at River Benue. Odour, turbidity, dissolved oxygen, (DO), total dissolved solids (TOD), biochemical oxygen demand (BOD) and chemical oxygen demand (COD), respectively also followed the same trend. No significant relationships existed between the occurrence and density of Azolla pinnata, Cyperus difformis, Kyllinga pumila, Pycreus lanceolatus (Poir.), Ludwigia decurrens, Leptochloa caerulescens Steud., Cardiospermum heliocacabum, Myriophyllum aquaticum, Pistia stratoites, Mariscus longibracteatus, Heliotropium indicum Linn., Sphenoclea zeylonica Gaertn.and Melochia corchorifolia and the water quality parameters at the study locations. However, positively significant relationships existed between the occurrence and density of Cyperus erecta and the pH of the water at River Benue and the amount of dissolved oxygen (DO) in water at the time of collection. There was a positive and highly significant relationship between Polygonium lanigerum R.Br., Heliotropium indicum, Persicaria decipens and Biochemical DO, BOD, COD and COD. Also, a positive and highly significant relationship existed between Ludwigia hyssopifolia and Sacciolepis africana with turbidity of water. The relationship to dissolved oxygen at time of water collection indicated the favorable disposition of these weeds to thrive and do well under conditions of relatively higher dissolved oxygen.