Distribution of Phytoplankton Communities Along the Lagos Coastline

Phytoplankton serve as primary producers in marine ecosystems, and their distribution patterns provide reliable indicators of oceanographic conditions and anthropogenic stress. This study investigates the spatial and seasonal distribution of phytoplankton communities along the Lagos coastline, South West Nigeria, an area exposed to intense urbanisation, port operations, and industrial effluents. Water samples are collected from six designated stations spanning the Lagos Bar Beach, Apapa Wharf vicinity, and Badagry Creek during the rainy and dry seasons of 2024. Phytoplankton identification and enumeration are conducted using light microscopy, with diversity indices including the Shannon-Wiener Index and Margalef Richness Index applied to assess community structure. Chlorophyll-a concentration is determined spectrophotometrically as a proxy for phytoplankton biomass. Temperature, salinity, nutrient concentrations (nitrate, phosphate), and turbidity are measured concurrently to correlate environmental drivers with community composition. Preliminary findings are anticipated to show dominance of diatoms during the dry season and increased cyanobacterial populations near sewage outfalls. Seasonal shifts in community structure are expected to reflect freshwater influence during peak rainfall periods. The research advances understanding of eutrophication dynamics in Nigerian coastal waters and provides data relevant to fisheries productivity assessments. Findings will be communicated to the Lagos State Environmental Protection Agency and the Nigerian Institute for Oceanography and Marine Research. Keywords: phytoplankton, Lagos coastline, eutrophication, seasonal distribution, coastal ecology