Phytoplankton diversity in the Cross River Estuary of Nigeria

Ao Ekwu,Fd Sikoki

doi:10.4314/jasem.v10i1.17296

Abstract

Studies on the species composition, relative abundance, spatial distribution and diversity of phytoplankton assemblages in the Cross River Estuary were carried out for twenty-four months, across six (6) sampling stations. A total of 105 species of 57 genera, belonging to 5 families were observed. Bacillariophyceae (Diatom) was the most abundant phytoplankton family, constituting 71.58% of total Algal density, followed by Chlorophyceae (Green algae) with 13.84%, Cyanobacteria (Blue-green algae) with 12.69%, while Euglenophyceae (Green flagellates) and Dinophyceae (Dinoflagellates) recorded 0.88% and 1.01% respectively, of total phytoplankton abundance. Bacillariophyceae showed progressive importance from stations 1 to 6 while chlorophyceae and Euglenophyceae were more abundant in stations 1, 2, and 3. Cyanobacteria however, showed no spatial bias, whereas Dinophyceae were observed only in stations 4, 5 and 6. Bacillarlophyceae was the most dominant family, while chlorophyceae and cyanobacteria were observed to be subdominant groups. Similarity of species occurrence was generally observed in stations 1 and 2, station 3 and 4 and stations 5 and 6. Analysis of variance (ANOVA) showed significant variation (P0.05) in composition of phytoplankton assemblages. High abundance of certain cyanobacteria taxa indicated environmental degradation. Journal of Applied Sciences and Environmental Management Vol. 10(1) 2006: 89-95

Highlights

Study area: The Cross River estuary lies between longitudes 8o001E and 8o401E and between latitudes 4o301N and 5o151N of the equator (Fig. 1)
The taxonomic listing of the phytoplankton species observed in the Cross River estuary during the study period is given in table 1, while the relative abundance of these organisms is shown in figure 2
Genera and cyanobacteria with 13 species belonging 9 genera. This sequence deviated from the report of Ekeh and Sikoki (2004) which stated a higher abundance of cyanobacteria than chlorophyceae in New Calabar River

Summary

Introduction

Study area: The Cross River estuary lies between longitudes 8o001E and 8o401E and between latitudes 4o301N and 5o151N of the equator (Fig. 1). This study was carried out to provide a concise set of structural based criteria (i.e. phytoplankton community composition, species diversity and distribution) for assessment of the environmental status of the estuary. The taxonomic listing of the phytoplankton species observed in the Cross River estuary during the study period is given, while the relative abundance of these organisms is shown in figure 2.

Results

Conclusion