Water quality and macroinvertebrate compositions of Obot Idim and Ikot Udo Ekpo/Akpasima Streams, Akwa Ibom State, Nigeria

Abstract

The study determined water quality and macroinvertebrate compositions, abundance and diversity of Obot Idim and Ikot Udo Ekpo/Akpasima Streams, Akwa Ibom State, Nigeria. Water samples were collected using sterile amber bottles from the two sampling sites to measure physico-chemical parameters, nutrient loads and heavy metal contents. Aquatic macroinvertebrates were collected with the aid of a standard kick-net of D-shape with 0.5m aperture, 1 x 1 square metre with mesh size of 500 µm and was coupled to a 2m long metal handle. Samples collected from the two streams were preserved in 70% alcohol and transported to the Laboratory for sorting and identification. Results of water temperature (28.00 – 30.00oC), pH (6.60-6.80), dissolved oxygen (3.20 – 4.20mgL-1), conductivity (110.00 – 180.00 µScm-1), nitrate (0.31 – 0.43mgL-1), and cadmium (0.01 – 0.02mgL-1) from the two streams were within recommended limits for freshwater bodies, and they were significantly different (p<0.05) among sampling sites. A total of 943 individuals of aquatic macroinvertebrates were collected from the two streams. The species, Lumbricus sp., Hirudo sp., Libellula sp. Coengrion sp., Celithemis sp., Gybister sp. and Chironomus sp were among the aquatic macroinvertebrate species collected from the sampling sites. Aquatic macroinvertebrates are an important component of freshwater ecosystems and are the most widely used in monitoring aquatic ecological status. It could be inferred from the present study that Ikot Udo Ekpo/Akpasima stream was more polluted than the Obot Idim stream.