The Seasonal Variations in Hydrological Factors in the Activity Zones: An Essential Examination of the Ecosystem in Badagry Creek, Lagos, Nigeria

The season is a pivotal representative in ascertaining the health status of a coastal ecosystem in a changing climate condition. The physico-chemical parameters of Badagry Creek were spatially and temporally investigated for twelve months (July 2017 to May 2018 for dry and wet seasons). Water samples were collected bi-monthly from nine stations, grouped into five activity zones during the water flow, covering upper, middle and lower courses. Seasonal variations in the physicochemical characteristics of Badgry Creek were found to be significantly different (<0.05) in salinity, phosphate, total suspended solids (TSS), total dissolved solids (TDS), depth, and dissolved oxygen (DO). Data were analysed using descriptive statistics, ANOVA and Spearman correlation at α₀.₀₅. The wet season had greater values of conductivity (551.27±79.09µS/cm; 412.77±42.7µS/cm) , pH (7.43±0.39: 7.41±0.41), salinity (5.04±1.11ppt: 1.22±0.40ppt), DO (6.72±0.26: 5.39±0.58mg/l), and chloride (Cl̉ˉ, 684.51±82.50 µmol/L: 674.22±73.44 µmol/L) than the dry season respectively. An increase in salinity during the wet season indicates the seawater intrusion and the waste discharge effluents from domestic and aquaculture processes into the stream from the higher course. Significant differences were observed between the Aquaculture (AQ) and Aquaculture combined Dredging (AQ_DG) zone for Sulphate and Chloride (Clˉ). The Biological Oxygen Demand (BOD) varied significantly between zones; they were 3.12±0.74mg/l in the Aquaculture zone (AQ) to 4.00±0.42 mg/l in the Domestic Waste (DW) zone and 2.10± 0.5 mg/l in the Aquaculture and Dredging (AQ_DG) zone to 19.2±9.44 mg/l in the Domestic Waste (DW) zone, respectively. The Highest value of TOM in DW station indicates anthropogenic effluents from domestic waste in this zone. The seasons were used to describe variations in Badagry Creek's physicochemical parameter values because the wet season noted higher parameter values, which may be related to an influx of water from the upper to the lower course.