Composition and abundance of rotifera in Ikpoba river, Benin, Edo state, Nigeria

Abstract

The present study investigated some selected physico-chemical parameters and the composition and abundance of rotifers in Ikpoba River from June to November 2009 to ascertain its ecological status due to the increasing anthropogenic activities on the river using rotifers. Water and zooplankton samples were collected from three stations between the hours of 10 am – 12 pm. Among the parameters measured, phosphate and nitrate were significantly different (P<0.05). However, signs of water quality deterioration were evident as revealed by the high variability in alkalinity and the nutrient factors. A total of nineteen taxanomic species of rotifera in seven (7) families were identified. Rotifera abundance followed this order of dominance; Philodinae (28.92%) and Lecanidae (21.46%), Proalidae (19.18%), Brachionidae (14.61%), and Testudinallae (10.65%), Asplanchnidae (4.87%) and Euchlanidae (0.76%) represented by a species. Station 3 was most diverse followed by Station 2 and then Station I while species richness and evenness followed a reversed order; Station 1>2>3. Principal component analysis implicated nutrients, organic, season and flow velocity as the four major factors influencing the composition and abundance of the rotifers in Ikpoba River.

Key Words: Rotifers, species richness, diversity, physico-chemical parameters, factor analyses and Ikpoba River