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Shorelines and adjoining land remain an important site for the intensive interplay of socioeconomic development and natural processes. Unfortunately, the Lagos, Nigeria shoreline is always subjected to varied morphological changes in response to small (short term) and large-scale (long term) events as triggered by natural processes and human development. Thus, there is the need to accommodate these changes through a combination of the relative permanence of urban infrastructure and shoreline defense efforts. The study assesses the evolution of the Lagos coast over 20 years, with reliance on archived Google Earth imageries dated between 2001 and 2020 to estimate and visualize the magnitude of erosion and accretion along the Lagos coastline with a focus on sections extending from the east mole to Victoria Island end, which form part of the Eti-Osa Local Government Area (LGA). This was achieved using the Analyzing Moving Boundaries Using R (AMBUR) software package, an R programming language add-in. Over the 20-year period, the Lagos shoreline cumulatively records a mean rate of change of + 0.93 m/year, mean erosion rate of − 1.94 m/year, and mean accretion rate of + 4.84 m/year. Focusing on Victoria Island where shoreline change is observed to be the highest, a mean shoreline change rate of + 6.24 m/year, depicting accretion activities is observed. Victoria Island also recorded a mean erosion rate of − 5.2 m/year and a mean accretion rate of 81.99 m/year. The high accretion rate and positive mean rate of change for Victoria Island and the entire Lagos coast results from land reclamation activities undertaken within the period of study. Further analysis of temporally segmented data into pre-reclamation, reclamation, and post-reclamation periods at Victoria Island reveals that eastward of Victoria Island is an active and unabated erosional activity resulting in disappearing beaches and urban developmental structures during the post-reclamation period. A post-reclamation period overall mean rate of − 4.73 m/year, with maximum erosion rate of 51.25 m/year are recorded for Victoria Island over a pre-reclamation period overall mean rate of − 1.41 and a maximum erosion rate of − 11.8 m/year. Therefore, an appropriate land use and land cover management plan needs to be adopted along the Lagos shoreline region, especially for Victoria Island.

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The advent of satellite-derived sea surface salinity (SSS) measurements has boosted scientific study in less-sampled ocean regions such as the northwestern Gulf of Guinea (NWGoG). In this study, we examine the seasonal variability of SSS in the NWGoG from the Soil Moisture Active Passive (SMAP) satellite and show that it is well-suited for such regional studies as it is able to reproduce the observed SSS features in the study region. SMAP SSS bias, relative to in-situ data comparisons, reflects the differences between skin layer measurements and bulk-surface measurements that have been reported by previous studies. The study results reveal three broad anomalous SSS features: a basin-wide salinification during boreal summer, a basin-wide freshening during winter, and a meridionally-oriented frontal system during other seasons. A salt budget estimation suggests that the seasonal SSS variability is dominated by changes in freshwater flux, zonal circulation and upwelling. Freshwater flux, primarily driven by the seasonally varying Intertropical Convergence Zone, is a dominant contributor to salt budget in all seasons except during fall. Regionally, SSS is most variable off southwestern Nigeria and controlled primarily by westward extensions of the Niger River. Anomalous salty SSS off the coasts of Cote d'Ivoire and Ghana especially during summer are driven mainly by coastal upwelling and horizontal advection.