The composition, abundance and distribution of zooplankton of River Niger at Onitsha stretch, Nigeria

The zooplankton assemblage of River Niger at Onitsha stretch was investigated at five sampling stations from January 2008 to December 2009. Some physical and chemical parameters were studied. Among these are: transparency, total alkalinity, conductivity, total dissolved solid (TDS), total suspended solid (TSS), total solid (TS), water level, nitrate, lead, iron and calcium varied significantly (p<0.01). Air and water temperature were significantly different (p<0.05) across the five stations. A total of 26 species of cladocera, 8 species of copepoda and 23 species of rotifera were encountered. The general diversity using Shannon Wiener and Margalef’s indices for zooplankton showed higher diversity in decreasing order of stations 2 > 4 > 3 > 5 >1. Similarity indices using Jaccard’s Bray Curtis and Euclidean distance indices showed that stations 1 and 5 and stations 2 and 4 respectively are more similar to each other, while station 3 is closer to 1 and 5 than it is to 2 and 4. The effect of adverse human activities and perturbations affect the composition and distribution of zooplankton at this study stretch.Keywords: Composition, Abundance, Distribution, Zooplankton, Onitsha, River Nige