Studies on the water quality and biota of a tidal eutrophic creek Lagos, Nigeria

Abstract

Investigations into the water quality and plankton of the Festival of Black Arts and Culture (FESTAC) creek were carried out between August 1998 and July 1999 using 55μm plankton net towed at low speed for 10mins.There were no significant seasonal differences (P>0.05) between surface water temperature (26.40 – 32⁰C), surface water pH (6.35 – 8.50) and PO₄-P values (1.55 – 22.98 mgL^-1). Whereas transparency (0.60-9.30 m), salinity (0.00–19.10 ‰),NO₃ – N (1.00–35.00 mgL^-1) and SO₄ 2- values (4.32-1987.0 mgL^-1) were lower in the rainy seasons, dissolved oxygen values were higher (0.32–4.80 mgL^-1) while Lead (0.63 mgL^-1) and Iron (15.42 mgL^-1)values were higher in the rainy season, Zinc recorded highest value (0.91 mgL^-1)in the dry season. Of the 58 plankton species identified (46 phytoplankton, 12 zooplankton), the pennate diatoms (36 taxa) and crustaceans (6 taxa) were the prevalent forms including environmentally important forms such as Eunotia gracilis, E.monodon, Navicula gracilis, N. mutica, Ulnariaulna, Nitzschia palea, Pinnularia braunii, P. gibba, Microcystis aeruginosa and Spirulina platensis. Of the 15 mudflat algae Nitzschia palea, Pinnularia braunii, P. gibba and Spirulina platensis were environmentally important species. The population of the benthic fauna was low (11 individuals) while the mud skipper was the most widely distributed fish.

Keywords: Water quality, biota, eutrophic, tidal, creek