Hydrobiological studies on Warri River, Nigeria: Part 1. The composition, distribution and diversity of macrobenthic fauna

Abstract

Hydrobiological investigation of macrobenthic fauna of WarriRiverwas carried out for a period of eighteen month from December 1991 to May, 1993 at monthly intervals.  Two stations designated along the main river course were sample for macrobenthos.  A total of 138 macro-invertebrate taxa comprising 5 was recorded.  The most dominant benthic groups were Copepoda, Decapoda, Ephemeroptera, Diptera and Mollusca.  Among the species encountered, naidium bilongata, Naidium breviseta, naidium osborni, nais obtuse, Placobdella monifera, Baetis bicaudatus and Vbaetis tricaudatus, are being recorded for the first time inNigeria.  Of all the assemblage of benthic organisms recorded in this study, species of Hirudinea, odonata and trichoptera were confined to station 1 and Mollusca to station 2, with species richness (d) being higher in the latter station.  Positive significant correlations were established between Diptera and crustacean/Odonata/Ephemeroptera and between Trichoptera and Arachnida and Ephemeroptera with odonata; Nematoda with Oligochaeta/Gastropoda.

    Application of Sorensen’s Quotient (Q/S) indicates great dissimilarity in species composition between the two stations.  Seasonal variations in most groups were the same in the two stations with distinct appearances in the dry season and at the end of rainy season months