The Physico-chemistry and benthic macro-invertebrate diversity and abundance of Nwaniba River, Akwa Ibom State, Nigeria

Abstract EN

The physico-chemical parameters and benthic macro-invertebrates’ diversity and abundance of Nwaniba River in Akwa Ibom State were studied between October, 2014 and January, 2015.

Surface water samples and benthic macro-invertebrate samples were collected from six (6) sampling stations according to standard methods.

The mean values of the measured water parameters were: Temperature (28.31±0.41) oC, Dissolved Oxygen (3.74±0.17) mg/l, Conductivity (16.41±1.80) µs/cm, Salinity (0.028±0.001) ppt, Total Dissolved Solids (15.75±4.53) mg/l and pH (6.9±0.12).

A total of 7 macro-invertebrate species belonging to 3 classes were encountered in the following order of abundance: Insecta (55.0%),Mollusca (40.0%) and Annelida (5.0%).

The most abundant species were Chironomus spp and Neritina cristata accounting for 8 (40.0%) and 5 (25%) respectively.

Whereas Segmentorbis augustus, Neritina rubricata, Pachymelania byronensis and Tubifex tubifex were the least abundant with 1 (5%) organism each.

The low abundance of benthic macro-invertebrates species and the total absence of the EPT indexed taxa, relative to a higher abundance of a pollution indexed taxa (Chironomus spp) may directly indicate the pollution stress level of this Nwaniba River system.

Hence, there is need for pollution management of this river.