Physicochemical characteristics of Nigerian estuaries and their patterns, drivers, and implications for environmental management
Year: 2026
Type: article
Abstract: Estuaries are dynamic coastal ecosystems that provide essential ecological, biogeochemical, and socio-economic services. Despite their importance, Nigerian estuaries remain underrepresented in global scientific literature, with existing studies fragmented and spatially uneven. This study systematically reviewed the physicochemical characteristics of surface waters and sediments in selected Nigerian estuaries, including Lagos Lagoon, Awoye, Bonny River, Imo River, and Qua Iboe River. Following PRISMA guidelines, literature published between 1990 and 2025 was reviewed, resulting in the inclusion of 56 studies from 162 screened records. Multivariate statistical techniques and pooled regression analyses were used to evaluate water-quality patterns, physicochemical relationships, and research gaps. The review revealed significant seasonal and longitudinal variations in pH and salinity across the studied estuaries. Dissolved oxygen (DO), nitrate (NO₃⁻), and phosphate (PO₄3⁻) generally decreased from upstream to downstream, although DO and PO₄3⁻ increased seaward in the Awoye Estuary. Surface-water metal concentrations varied longitudinally, while sediment-associated metals exhibited stronger seasonal influences. Cadmium showed moderate spatial variability, whereas lead, copper, nickel, zinc, and iron differed significantly among estuaries. Principal component analysis identified five components explaining 72.16% of the total variance, reflecting major physicochemical and anthropogenic processes. Pooled regression further indicated that spatial variability generally exerted a greater influence on physicochemical conditions than seasonality. Strong metal–nutrient correlations (r ≥ 0.7) suggested substantial anthropogenic inputs from wastewater discharges, industrial effluents, and agricultural runoff. The review identified that only 8.9% of the reviewed studies assessed entire estuarine systems, highlighting a major evidence gap. These findings emphasize the need for integrated catchment-to-coast monitoring, localized water-quality thresholds, and strengthened pollution control measures to support Sustainable Development Goals 6 and 14 in Nigeria’s estuarine ecosystems and blue economy.
Source: Discover Oceans
Institution: Federal University of Technology
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7221453124