环境与分析毒理学

Application of Biotic Indices and Pollution Tolerance Index in Assessing Macro-Invertebrate Assemblage of Ediba River, Cross River State, Nigeria

Abstract

Andem AB, Esenowo IK and Bassey DO

The study of the macro-invertebrates community of Ediba River in Cross River State was carried out from October to December, 2014 using Pollution Tolerance Index (PTI). Macro-invertebrate fauna were sampled with sweeping net using kick sampling methods. Sixteen genera, belonging to nine orders and a total of 289 individuals were encountered. The dominant groups in the order were Oligochaeta (29.1%)>Diptera (24.62%)>Odonata (20.3%), showing insignificant difference between the three stations at p>0.05. Taxa richness was highest in Station 1 (2.985) and least in Station 3 (1.008) showing insignificant differences across station (p>0.05). Evenness ranges from 0.337 to 0.369 showing significant difference across stations (p<0.05). Station 1 had a PTI value of 39 indicating good quality water status, while Stations 2 and Station 3 had PTI values of 6 and 4 respectively indicating poor quality water status. The abundance of pollution tolerance species of the orders, Odonata Zygoptera, Oligochaeta, Diptera and the absence of pollution sensitive species of the orders, Ephemeroptera and Trichoptera in Stations 2 and 3 indicated the poor waters quality, coupled with the low PTI values in both stations, hence need for proper management of the river.