Ichthyofaunal Assemblages of some Nigerian Rainforest Streams

Abstract

The fish faunal assemblages of two first-order (Udom and Nung Oku), two second-order (Esedeke and Iba Oku) and one third-order (Ikpa) streams in Akwa Ibom State (southeastern Nigeria) were investigated. The fishes comprised a total of 55 species from 43 genera and 24 families. Ikpa stream had the highest taxa richness (40 species, 35 genera, 24 families) while Udom stream had the lowest (17 species, 15 genera, 10 families). Of fish species identified, only 8 were common to the five streams (Chromidotilapia guntheri, Hemichromis fasciatus, Thysochromis ansorgii, Epiplatys sexfasciatus, Malapterurus electricus, Brienomyrus brachyistius, Papyrocranus afer and Erpetoichthys calabaricus). Species richness and diversity increased with stream order. Diversity indices were relatively high whereas equitability (evenness) indices were low in all streams. Similarity indices were low except for the Udom-Nung Oku pair (72.22%) and Iba Oku-Esedeke (60.46%) pairs. Thus streams of the same order harboured similar fish faunal assemblages. The streams were acidic (reflecting the nature of the predominantly laterite soils of adjoining lands) except for Ikpa stream which was minimally alkaline.


Journal of Aquatic Sciences Volume 15, April 2000, pp. 1-8





KEY WORDS:

Fishes, check-list, stream-orders, southeastern Nigeria.