Some observations on the zooplankton and macrobenthos of the Okhuo River, Nigeria

Abstract

Some abiotic and biotic habitat characteristics of the shallow Okhuo River (average depth 0.85 m) were determined and are described. Water temperature (25.80C) is slightly lower than 25.90C of air. The mean conductivity was 291.4 m Scm-1. The pH is low (5.63) as the alkalinity (8.95mg CaCO3 l-1). The low biochemical oxygen demand (2.94 mg l-1) and high dissolved oxygen (11.1mg l-1) indicate low level of organic matter in the water. Ephemeroptera and Oligochaeta are widely distributed and not inclined to habitat restrictions. Oligochaetes (8.8%), rotifers (72.60%), cladocerans (8.64%), copepods (15.52%), ostracods (3.65%), shrimps (15.9%), insects (75.3%) were sorted out and identified from the collections. Numerically rotifers (72.60% of plankton) and insects (75.3% of benthos) were dominant. The proportions of biota (Ephemeroptera, 67.2%; Chironomidae, 8.1%) interplaying with the physico-chemical characteristics are conducive to cleanliness of the Okhuo River.


Key words: Zooplankton, Macroinvertebrates, Nigeria.


Journal of Aquatic Sciences Vol.17(2) 2002:145-149