Assessment of the structure of the macroinvertebrate community in the lower Section of the River Adofi, Nigeria.

Abstract

This study assessed the macroinvertebrate community structure of the Adofi River at three (3) ecologically distinct stations by collecting water samples in plastic containers and macroinvertebrate samples using a D-shaped net for 12 months, from December 2020 – November 2021 and analysed in the laboratory using standard methods. The results of physico-chemical
parameters ranged between: air temperature (27-32) °C, water temperature (26-30) °C, pH (2.1-7.4), dissolved oxygen (5.4-9.8) mg/L, water depth ( 59-154.2)cm, alkalinity (180-280), conductivity (102-132.5) µs/cm, acidity (48-76) mg/L, TDS (80-130) mg/L, phosphate (1-3) mg/L, sulphate (204-52)mg/L, and nitrate(14.5-26.4) mg/L. ANOVA analysis showed that waterdepth, alkalinity, and sulphate values were statistically significant between the three sampled stations at P≤0.05. 777 macroinvertebrate organisms
ranging from Coleoptera, Hemiptera, Odonata, Gastropoda, and Arachnida, were collected in this study. Hemiptera dominated with 452 individuals and accounted for 58% of the macroinvertebrate group, and Odonata was the least with 39 individuals. Gerris lacustris dominated, while Ilyocoris cimicoides was least abundant and found only in station 1. The CCA triplot showed that D.O, water depth, TDS, and BOD supported the abundance of Dolomedes sp., Pseudomacronucleus sp., and macromiidae sp. in station 1