Macroinvertebrates as bioindicators of Water Quality of Effluent-receiving Ossah River, Umuahia, Southeast Nigeria.

Abstract

Bioindicators are biological organisms that can be used to monitor the quality of the environment. Macroinvertebrates are known to be extremely sensitive to organic pollutants coupled with their wide distribution, ease and minimal cost of sampling which makes them perfect bioindicators. Macroinvertebrate fauna of an effluent-receiving River Southeast Nigeria was studied in 3 stations between January and June 2018; to assess their community structure in relation to effluent discharge and other anthropogenic activities. The modified kick sampling technique and sweeping of aquatic macrophytes with hand net were used in the sampling of the macroinvertebrates. Five taxonomic groups and twenty (20) taxa were recorded; contributing 119 macroinvertebrate individuals. The composition of the taxa showed that non-biting midge, Chironomus sphad the highest number (39.5%). In terms of spatial distribution, the highest number of individuals (57) was recorded in station 2 while stations 3 and 2 had 37 and 25 individuals respectively. The macroinvertebrates fauna was dominated by tolerant species (75%). The diversity indices as reflected in Shannon-Wiener index (H) (1.717 - 1.923), Magalef Species Richness (2.769 - 2.968) and Evenness index (0.4285 - 0.6843) were low indicating lower number of species and environmental degradation due to anthropogenic impacts. The physicochemical parameters and macroinvertebrate assemblages showed that the river was adversely impacted by effluent discharge and other anthropogenic activities. The physicochemical parameters showed that station 1 was polluted by cumulative impacts while macroinvertebrate assemblages showed that station 2 was polluted by effluent discharge.