SEASONAL VARIATIONS IN PHYSICOCHEMICAL PARAMETERS AND NUTRIENTS IN FIVE COWRIES CREEK NIGERIA: IMPLICATIONS FOR AQUACULTURE

Abstract

Aquaculture development in estuarine systems depends on maintaining good water quality, and transparency is a
key indicator of trophic status. This study evaluated the suitability of Five Cowries Creek, Lagos for aquaculture
by characterizing seasonal and spatial variability in transparency and key water quality variables. Twenty
sampling stations across three zones were monitored over a 24-month period (November 2023–November 2025),
with emphasis on dry (March) and wet (July and November) seasons. Physicochemical parameters were
measured in situ, while nutrients and chlorophyll-a were analyzed in the laboratory. Seasonal means showed
consistently adequate oxygenation for finfish culture (DO 6.02 ± 0.54 mg L⁻¹ in the dry season; 6.41 ± 0.47 mg L⁻¹
in the wet season), while wet-season runoff markedly increased turbidity (23.41 ± 0.82 vs. 13.93 ± 15.33 NTU) and
nutrient enrichment (PO₄³⁻ 4.82 ± 6.22 vs. 3.37 ± 4.68 mg L⁻¹), coinciding with reduced transparency (58.71 ±
1.31 vs. 113.56 ± 46.57 cm) and episodic extremes (turbidity >60 NTU; Secchi depth ~30–36 cm; PO₄³⁻ >14 mg
L⁻¹; NH₃ up to 0.71 mg L⁻¹; NO₃⁻ up to 11.81 mg L⁻¹; NO₂⁻ up to 0.591 mg L⁻¹). PCA explained 84.71% of the total
variance (PC1 50.43%, PC2 19.74%, PC3 14.54%) and resolved dominant gradients driven by the clarity
oxygenation versus turbidity phosphate axis, nitrogen speciation (ammonia nitrate opposition), and redox-linked
internal nutrient processing. Overall, Five Cowries Creek can support aquaculture, but wet-season turbidity and
nutrient pulses elevate eutrophication and localized oxygen-stress risk; the dry season represents the optimal
production window.