Spatiotemporal dynamics of microplastics, mesoplastics and macrolitter in Cypriot shores: An integrated size assessment to discern transport pathways

Microplastics and mesoplastics have become integral components of marine debris and the broader global plastic pollution crisis. Their increasing prevalence and environmental hazards have driven worldwide monitoring efforts, often alongside beach macrolitter surveys, to establish source linkages critical for informed policy and management. Employing standardized sampling protocols, this study establishes baseline spatiotemporal dynamics of microplastics (1-5 mm) and mesoplastics (5-25 mm) in the Republic of Cyprus, characterises their typologies and identifies key contamination drivers. It further introduces a newly improved attribution scheme to evaluate shoreline vulnerability to debris loads arising from distinct transport pathways. Mean abundances recorded were 336 particles m⁻² (0.819 g m⁻²) for microplastics, 107.5 particles m⁻² (1.086 g m⁻²) for mesoplastics, and 0.459 items m⁻² for beach macrolitter. Particle loads exhibited heterogeneous physical profiles and fine-scale spatial variability, influenced by hydrodynamic exposure and temporal factors, with particle retention likely governed by coastal morphology. Approximately 69% of shorelines were susceptible to sea-based debris, 6% to land-based inputs, and 25% being heavily impacted by marine-derived plastic pollutants. These findings underscore the magnitude of marine debris contamination in the eastern Mediterranean and emphasise the necessity of an integrated, multi-faceted monitoring approach that enables local authorities to allocate resources strategically, tailored to dominant transport pathways, for effective plastic pollution management and mitigation. • Baseline microplastic (1-5 mm) & mesoplastic (5-25 mm) loads for Republic of Cyprus coastlines. • Mean abundances: 336 particles m⁻² (microplastics), 107.5 particles m⁻² (mesoplastics). • Spatial variability driven by hydrodynamic exposure, temporal factors, coastal morphology. • New shoreline vulnerability scheme identifies dominant sea- vs land-based debris pathways. • Findings support pathway-specific strategies for marine plastic pollution management.