Driftwood as a passive retention structure for marine litter.

Driftwood is a ubiquitous component of coastal environments, yet its functional role in trapping marine litter remains poorly understood, particularly in tropical systems. This study investigates the relationship between driftwood abundance and litter accumulation across seven remote beaches of the central Caribbean coast of Colombia. A standardized quadrant-based field protocol was applied to quantify and classify 12,129 items, including 3990 driftwood pieces and 8139 litter items. Plastics represented 92 % of total litter, with foam sponge, caps, and fragmented packaging as dominant types. Driftwood indices showed strong spatial variation and were positively correlated with total litter and plastic densities. Sites with greater driftwood presence consistently exhibited higher litter accumulation, suggesting a passive retention mechanism. Multivariate ordination and cluster analyses revealed that driftwood-rich beaches formed distinct assemblages dominated by lightweight, floatable plastic items. Although Indicator Species Analysis did not yield statistically significant item-driftwood associations, qualitative patterns supported selective entrapment. These findings position driftwood as a key modulator of litter retention in remote beach systems. Beyond its ecological role, driftwood also holds predictive potential: linear relationships and derived ratios (LDR, PDR) offer scalable metrics for identifying pollution hotspots.