Epilithic Diatoms of Urban River Dilimi, Jos, Nigeria

Abstract

For a long time now, diatoms have been used to determine the ecological integrity of freshwater bodies. Despite the ecological significance of diatoms in freshwater bodies, the taxonomic composition and autecology of diatoms in many freshwater bodies of Nigeria are yet to be investigated. The present work was carried out to ascertain the taxonomic composition of epilithic diatoms of River Dilimi in Jos, Nigeria. The physical and chemical properties of the river at two urban stations (were diatoms were sampled) were also determined. Mean NO₃ (mg l⁻¹) was 0.9 (± 0.14) at the upstream station and 1.06 (± 0.08) at the downstream station. Mean PO₄ (mg l⁻¹) was 0.03 (± 0.14) at the upstream station and 1.3 (± 0.7) at the downstream station. A total of 28 diatom genera and 83 species were documented from the study sites. Out of the 83 species, 59 occurred at the upstream site and 45 at the downstream site. The percent community similarity between the two sites was 24.71 %. At the upstream site the most common species were Meridion circulare (3.5 %), Navicula mutica (3.6 %), Nitzschia amphibia (3.0 %) and Synedra ulna (3.4 %). At the downstream site the most common species were Cyclothella meneghiniana (4.4 %), Nitzschia amphibia (8.8 %), Nitzschia palea (5.0 %), Synedra ulna (12.8 %), Tabellaria fenestrate (3.8 %) and Tabellaria flocculosa (3.1 %). Since both NO3 and PO4 concentrations in the river indicate that the river is polluted, the diatoms recorded in this study may be grouped as pollution tolerant diatoms, bearing in mind, too, that the river water is discoloured throughout the year.