Ecological Impact Assessment and Limnological Characterization in the Intertidal Region of Calabar River Using Benthic Macroinvertebrates as Bioindicator Organisms

Abstract

A study on ecological impact assessment and limnological characterization of Calabar River using benthic macroinvertebrates as bioindicators organisms was conducted from August, 2012 to January, 2013. Surface water and benthic samples were collected from two different stations along the intertidal region of the river. The mean value of surface water temperature was 28.0±0.71 ° C; pH, 8.20±0.35; dissolved oxygen, 4.30±0.4 mg/L; biochemical oxygen demand, 2.30±0.26 mg/L; conductivity, 281.8±89.5 mg/L; There were significant differences (p <0.05) in the mean values of conductivity in the sampling stations. Three phyla of benthic macroinvertebrates were encountered in the River. The first Phylum, Arthropoda was represented by five genera and four species. The second Phylum, Annelida was represented by only one genus, Capitella (Polychaeta). The third Phylum, Mollusca was represented by seven species of gastropods. Pachymelania fusca dominated the benthic macroinvertebrate with a total relative abundance of 50.0% by number while Hemigrapsus species and Capitella species were the least abundant, 0.13% by number. All the benthic macroinvertebrate fauna recorded were pollution-tolerant and clean water species. This could influence the distribution and abundance of benthic macroinvertebrates in the intertidal region of Calabar River and that the river could also be under pollutional stress because the benthic macroinvertebrate observed were pollution-tolerant and clean water species