Abstract
<title>Abstract</title> <p>8mical processes, and ecosystem structure remain poorly quantified. This study integrates field-based ecological analyses with a systematic review to investigate the drivers and consequences of coastal ecosystem change. A PRISMA-based review was conducted to synthesize regional knowledge on coastal biogeochemical dynamics, while ecological data were analyzed to assess spatial and temporal patterns of coral reef degradation, biodiversity change, and environmental forcing. Results reveal a significant decline in coral cover along the disturbance gradient, accompanied by a shift toward macroalgal dominance, indicating a regime shift in benthic composition. Structural complexity emerged as a key determinant of ecosystem resilience, strongly enhancing fish biodiversity and biomass. Fish assemblages showed pronounced reorganization under increasing disturbance, with marked losses in biomass and functional diversity. Multivariate analyses identified nutrient enrichment and sea surface temperature anomalies as primary drivers of reef degradation, with strong evidence of synergistic effects between local and global stressors. Importantly, structurally complex reefs exhibited greater resistance to these combined pressures. The systematic review further confirms that coastal biogeochemical processes in the Gulf of Guinea are tightly controlled by interactions between physical forcing and nutrient dynamics, while highlighting critical gaps in long-term observations. Overall, this study demonstrates that coastal ecosystems in the Gulf of Guinea are highly sensitive to coupled climate–anthropogenic stressors. Strengthening integrated monitoring systems and adopting ecosystem-based management strategies are essential to enhance resilience and sustain ecosystem services in this vulnerable region.</p>