Impact of Locally Refined Diesel on Macroinvertebrate Community of Ekehuan and Gelegele River, Edo State

Abstract:

This study was carried out between April 2013 and January 2014 to investigate the impact of locally refined diesel on the abundance and diversity of macroinvertebrate fauna in Ekehuan and Gelegele Rivers in Edo State. Water and macroinvertebrate samples were collected from three sampling points in the study area. The water samples collected were analysed for total hydrocarbon concentration (THC) among other environmental parameters like air and surface water temperature, pH, conductivity, dissolved oxygen (DO), biological oxygen demand (BOD), and chemical oxygen demand (COD). While, Dissolved Oxygen (DO), Water and Air Temperatures were significantly lower at sampling station 1, THC was considerably higher at the same sampling station 1. A total of 16 species comprising 510 individuals were encountered in this study. The class of macroinvertebrates encountered in this study were Class Insecta, Malacostraca, Phasmidea, Oligochaeta and Gastropoda. The diversity and abundance of macroinvertebrates were significantly (P<0.01) lower at sampling station 1 than at the other sampling stations 2 and 3, which were themselves very similar with respect to species diversity and composition. There was a high correlation between the abundance of macroinvertebrates and the level of hydrocarbon in the water. Therefore, it is evident that the presence of locally refined diesel has significantly reduced the diversity and abundance of macroinvertebrate.