Species diversity and abundance of Oligochaeta fauna in a tropical rain forest lake in South-Southern, Nigeria

Abstract

The composition, distribution and abundance of Oligochaeta in Obazuwa lake of Benin City in Edo State, South-Southern Nigeria was investigated between July 2014 and June 2015. The findings, revealed a total of 18 Oligochaeta taxa and 482 individuals comprising, 11 species of Naididae family, 1 species of Aeolosomatidae family, and 6 species of Tubificidae family. The percentage abundance of Oligochaeta in the study stations showed that Naididae had the highest abundance of 66% followed by Tubificidae and Aeolosomatidae recording 28% and 6% respectively. Naididae was predominant and widespread in the study stations. The abundance and community structure of Oligochaeta in this study showed significant variations (P<0.05). The diversity indices indicated that taxa richness (d), Shannon –Wiener (H) and Evenness (E) are highest at station 1 and lowest at station 2. Jaccard’s coefficient of similarity of species revealed significant similarity between the two stations studied (P>0.05). The impact of seasonal variations, human activities and environmental factors influencing the distribution and abundance of Oligochaeta are observed. There is a need for freshwater biologists to investigate the developments in Oligochaeta ecology in lakes and other freshwater ecosystems.

Key Words: Oligochaeta, Naididae, Aeolosomatidae and Tubificidae, Obazuwa Lake