BENTHIC MACROINVERTEBRATE COMMUNITY OF A TROPICAL RAIN FOREST RIVER IN SOUTH-WESTERN NIGERIA

Abstract

The composition and distribution of the benthic macroinvertebrate fauna across a section of Osse River in Ondo State, Nigeria was investigated between February and July 2009. Among the physical and chemical parameters studied, flow rate was significantly higher (P < 0.001) in station 2 than other stations which were not significantly different (P > 0.05) from each other. The twenty-six taxa recorded were encountered in the four stations. Diptera accounted for 66.81%, Ephemeroptera (17.85%), Oligochaeta (5.95%), Odonata (5.03%), Decapoda (1.59%), Hemiptera (1.26%), Mollusca (0.17%), Trichoptera (0.64%), and Plecoptera (0.09%) were the major groups collected from the study stations. The familes Chironomidae (Diptera), Baetidae (Ephemeroptera), Lumbriculidae (Oligochaeta) and Libellulidae (Odonata) were the most dominant and widespread. The abundance and community structure showed significant variations (p < 0.05) between the study stations. A posteriori Duncan Multiple range (DMR) test showed that the abundance was significantly higher (P < 0.05) in stations 2 and 4 than the other stations (1 and 3). The Diversity indices revealed that taxa richness (d), Shannon-Wiener (H„) and Evenness (E) were highest in station 2 and 3. Taxa richness (d), and Shannon-Wiener (H„) were lowest in station 1. The impact of cultural eutrophication on the abundance and diversity of macrobenthic invertebrate fauna is reported