Land-based anthropogenic pollutants and their ecological impacts on marine ecosystems: A scoping review with implications for Small Island Developing States and Mauritius.

Globally, land-based pollution accounts for approximately 80% of marine degradation. However, evidence connecting terrestrial sources to ecological outcomes remains fragmented across scientific disciplines, geographic regions, and pollutant categories. This Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guided scoping review mapped 98 studies to identify dominant pollutants, land-sea connectivity pathways, and ecological impacts, with particular focus on Small Island Developing States (SIDS), including Mauritius. Heavy metals (n = 31), nutrients (n = 27), and pesticides (n = 14) were the most studied pollutant categories, transported primarily via river discharge, surface runoff, and submarine groundwater discharge. Observed ecological impacts included bioaccumulation, eutrophication-driven phase shifts, and coral reef degradation, even when pollutant concentrations were below regulatory thresholds. The Mauritian evidence base (n = 18) aligned with global trends regarding heavy metals and microplastics; however, significant gaps were identified in pesticide research, integrated land-sea pathway assessment, and long-term ecological monitoring. These findings underscore the need for a precautionary, catchment-to-coast management approach for SIDS, where short catchments and high dependence on the marine environment increase pollution risks.