Ekperusi et al. 2026 - Assessment of Ocean Acidification Trends in Nigeria (2010–2024)

Abstract As a planetary process, ocean acidification has crossed its boundary due to rising atmospheric CO₂, yet data scarcity limits understanding of its impacts on marine ecosystems in the Global South. This study fills a critical gap in the Gulf of Guinea by analysing trends in certain oceanographic chemical properties in Nigeria's coastal waters from 2010 to 2024, using data on pH, carbon, salinity, alkalinity, dissolved oxygen, and temperature. Results show a mean pH of 7.01±0.31, far below the open-ocean average of 8.1, driven by local stressors that amplify global signals, with a significant pH-carbon correlation (r = -0.504, p < 0.05). Salinity (mean 12.84±18.31 ppt) and temperature (mean 28.00±0.93 °C) reflected the estuarine and tropical character of the study area. Alkalinity (mean 128.26±201.47 mg/L) showed high variability indicative of fluctuating buffering capacity, and dissolved oxygen (mean 5.32±1.01 mg L-1) exhibited moderate inter-annual variation. Time-series models project that pH will decline to 6.8 – 6.9 by 2039. This study enhances global models' underrepresentation of tropical estuaries and supports efforts towards the Global Ocean Observing System for SDG 14.3 in the Gulf of Guinea.