The Rotifera Fauna Of Gongola River Basin, Northeast Nigeria

Abstract

This study was undertaken to characterize the taxa composition, distribution pattern and the abundance of rotifers in surface waterbodies in the Gongola basin of Nigeria, West Africa. It was based on the analysis of net zooplankton samples collected from the River Gongola, its flow-through reservoirs, borrow-pit ponds and pools, over the two seasons of one annual cycle. The Rotifera fauna comprised thirty Monogononta species dominated by members of families Brachionidae (43 %) and Lecanidae (23 %). The fauna showed high similarity with those of most other Nigerian inland waterbodies and all the species are either cosmopolitan or cosmotropical in zoogeographical distribution. About one half of the recorded species occurred common to both the lotic and lentic waterbodies while about 40% and 10% were restricted to lotic water and lenthic waters respectively. The most widely distributed and abundant species were Keratella tropica and Brachionus calyciflorus while the two species restricted to lentic waterbodies were Asplanchna priodonta and Mytilina ventralis. A number of species showed a definitive pattern of distribution along the horizontal course of the River Gongola. These included Keratella tropica, K. lenzi, Filinia opoliensis and Lecane curvicornis which increased downstream as opposed to Lecane bulla and Platyias quadricornis which decreased downstream. Species richness and diversity indices generally increased downstream while species evenness index decreased downstream. Some species varied with the size of lentic waterbodies while others showed potential to serve as indicators of water habitat type. The fauna was qualitatively richer but quantitatively poorer during the rainy season than in the dry season due to the associated effects of rainfall, stream discharge and physico-chemical water quality.

Keywords: Rotifera zooplankton, community structure, distributional pattern, Gongola basin, West Africa

IFE Journal of Science Vol. 9 (1) 2007 pp. 1-16