Variation in benthic macroinvertebrate assemblages in Ologe Lagoon, Nigeria

Abstract

The community structure, diversity and seasonal variation of the benthic macroinvertebrates in Ologe Lagoon were studied at four sites during the dry and wet seasons of 2003 to provide environmental baseline data for the lagoon. The community comprised 29 taxa from the phyla Insecta, Annelida, Mollusca, and Crustacea, with more taxa recorded during the dry, than in the wet season. An average of 254 individuals m^–2 were found in the samples, of which 57.5% (146 individuals m^–2 were recorded during the dry season and 42.5% (108 individuals m^–2) during the wet season. No significant differences (p > 0.05) in abundance were found among seasons. The most abundant benthic fauna were insect larvae, which were dominated by Ephemeroptera and Diptera, accounting for 44.1% of the population sampled. Crustaceans, annelids and molluscs were the next most abundant and represented 33.1%, 13.4% and 9.4% of the total population, respectively. Taxon diversity was highest at Elete Creek. However, no significant difference (p > 0.05) in the number of taxa was found across the four stations with season.

Keywords: freshwater lagoons, seasonal community variation, population abundance, dominant taxa

African Journal of Aquatic Science 2008, 33(1): 45–50