Epilithic Soft Algae of Dilimi River in Jos, Nigeria

Abstract

River Dilimi flows through urban areas in Jos, Nigeria. As a result of this, a lot of human-generated pollutants find their way into the river. The locals attach a lot of socio-economic importance to the river. But the scientific community has shown minimal interest in the ecology of the river. Hence, there is a dearth of information in the literature about the biotas (especially soft algae) that inhabit the river. Epilithic soft algae were sampled from the river at two sites (an upstream site close to British-America bridge, and a downstream site at the pedestrian bridge, Unijos permanent site). Nutrients (N and P), biochemical oxygen demand (BOD), conductivity, and total dissolved solids (TDS) levels were relatively higher at the downstream site, which suffers more from anthropogenic pollution. Seven Divisions of soft algae were registered during this study. Cyanobacteria, Charophyta, Chlorophyta and Dinophyta were recorded at the upstream site. The fore-mentioned Divisions (excluding Dinophyta) plus Euglenophyta, Ochrophyta and Cryptophyta were observed in samples collected at the downstream site. Cyanobacteria was the most common group of soft algae at the upstream site with 82 % occurrence. At the downstream site, Chlorophyta was the most common group with 35 % occurrence, followed by Cyanobacteria (29 % occurrence) and Euglenophyta with 16 % occurrence. A total of 78 species of soft algae were recorded in this study. The downstream site was richer in species (57 species vs. 30 species at the upstream site), and had a higher diversity index value (3.89 vs. 2.67 Shannon index at the upstream site). The community similarity index between the two sites was low (11.5 %). This study is the first to describe the community of soft algae in River Dilimi, a grossly polluted river. Hence, the documented soft algae could be described as pollution tolerant organisms.