Beach debris on Aruba, Southern Caribbean: Attribution to local land-based and distal marine-based sources

• 42,585 macro-debris items and 884 meso-debris items were collected on Aruba's beaches.
• Novel metrics attribute debris to local-land based or distal marine-based sources.
• Local land-based sources were dominant on leeward coastlines.
• Distal marine-based sources were dominant on windward coastlines.
• The metrics considered provide a promising means to identify debris source origin.

Accumulation of marine (plastic) debris from local land-based and distal marine-based sources along coastlines is a pressing modern issue. Hitherto, assessing the relative contribution of pollution sources through beach surveys is methodologically challenging. We surveyed ten beaches along the leeward and windward coastlines of Aruba (southern Caribbean) to determine differences in macro- and meso-debris densities. Differences were quantified using three metrics: 1) the gradient in macro-debris density away from the waterfront; 2) the proportion of plastic within macro-debris; 3) the meso-:macro-debris ratio. Overall 42,585 macro-debris items and 884 meso-debris items were collected. The density of near-shore macro-debris, proportion of plastic debris herein, and meso-:macro-debris ratio were highest on the windward coastline. These results suggest that southern Caribbean windward coastlines are mainly exposed to debris originating from distal marine-based sources, and leeward coastlines to local land-based sources. Our metrics clearly reflect these differences, providing novel means to survey debris source origin.