Seasonal variation of the hydro-environmental factors and phytoplankton community around waters in Tincan Island, Lagos State, Nigeria

The phytoplankton diversity, pigment, abundance and distribution in relation to physico-chemical parameters were studied from four stations for a period of five months (May – September 2018) and were analysed using standard procedures. Rainfall was highest (329.5 mm) in September and lowest (142.7 mm) in July. The total suspended solid (TSS) had a mean value of 63.10±12.81 mg/L and the total dissolved solids (TDS) had the highest value of 15189 mg/L in May which was not significantly different around the sampling points {P > 0.05}. The pH and nitrate level recorded had a mean value of 7.25±0.33 and 3.11±1.33 mg/L respectively. Microscopic identification revealed a total of 129 species belonging to 62 genera, 22 families and five divisions in the following order of specie abundance: Bacillariophyceae (65 taxa) > Cyanophyceae (27 taxa) > Chlorophyta (20 taxa) > Dinophyceae (10 taxa) > Euglenophyceae (7 taxa). The high dominance of Microcystis aeruginosa observed was indicative of organic pollution. The range of community structure indices were as follows: Margalef Index (0.1406 – 5.295) and Shannon – Weiner Index (0.02644 - 0.4979). The relatively high nutrient status favours the high abundance of phytoplankton which is understood to be deleterious to the ecosystem. Municipal wastes must be treated or recycled before discharge and a continuous environmental surveillance is required to maintain the biological integrity of this area. Keywords: Phytoplankton, Physicochemical Parameters, Nutrient Status and Tincan Island