RELATIONSHIPS BETWEEN WATER PHYSICO-CHEMICAL PARAMETERS AND BENTHIC MACRO INVERTEBRATES OF THE MIDDLE REACHES OF ORASHI RIVER, NIGER DELTA

Abstract

Orashi River is one of the major rivers that drain the River Niger through the Niger Delta into the Atlantic Ocean. The relationship between the physio-chemical properties of the river water and benthic macro invertebrates were studied between October 2017 and September 2018. Monthly samples of the river surface water and macro invertebrates were collected at five sampling stations using standard methods. Means and standard deviation of the water parameters were determined and correlated with the macro benthos to determine their relationship.Oligochaeta was represented by 9 species; Crustacea had 3 species while 2 species were identified under Insecta. Temperature (0C) ranged between 27 0C and 29.40C. Conductivity fluctuated between 18 – 48.4μS/cm and pH was from 6.10 – 7.96. Salinity and turbidity ranged between and 0 – 0.02 and 8.50 – 107.7 NTU respectively. Total dissolved Solids (TDS) was from10 – 25.18 mg/L, Biological oxygen demand (BOD) 6.01 – 7.88 mg/l, Chloride 1.05 – 6.42mg/l, total alkalinity 3 – 9 mg/l and total hardness 2.29 – 9.93 mg/l. Nitrate, sulphate, Chromium, Iron and Zinc were between 0.05 – 0.95 mg/l, 2.10 – 10.31 mg/l, 0.003 – 0.08 mg/l, 1.542-4.966mg/l and 0.003-0.338 respectively. Correlation between macro benthos was positive with sulphate and DO but negative with Zinc, turbidity and BOD.There is need for effective monitoring of the river system to be able to detect environmental changes that could be corrected for a sustainable ecosystem.