Macroplastic survey on a sea turtle nesting beach at the Pacific coast of Guatemala

Sammendrag

Plastic pollution poses a growing threat to coastal ecosystems, including sea turtle nesting habitats, yet data from Central America remains scarce. We quantified and mapped macroplastic (> 5 mm) pollution on a sea turtle nesting beach along the Pacific coast of Guatemala by applying both unmanned aerial vehicle (UAV) surveys and ground-based monitoring. We analyzed plastic abundance with negative binomial mixed-effects models, accounting for sampling method, beach level, and vegetation presence. Ground-truthing revealed a total of 12,297 macroplastic items, corresponding to an average of 2102 items per 100 m shoreline, exceeding the OSPAR beach litter threshold 100 times. Polystyrene, minor pieces, industrial packaging, lids, sweet packets and lolly sticks, cutlery and straws, and bottles were the most abundant. Most classified and identified plastic originated from land-based sources, with accumulation near the high-tide line and within vegetated beach zones- areas that overlap with preferred sea turtle nesting habitat. Ground-based surveys detected ca. 15 times higher plastic abundances than UAV imagery, particularly in vegetated areas, where aerial detection was limited. However, the integration of UAVs with ground-truth interpolation facilitated large-scale beach coverage. To our knowledge, this study provides the first systematic assessment of macroplastic pollution on Guatemala’s Pacific coast. It highlights both the severity of plastic contamination on a sea turtle nesting beach and the need for pollution monitoring, and it emphasizes the trade-offs between detection accuracy and survey efficiency. Integrating ground surveys with aerial methods offers a scalable approach for identifying pollution hotspots and informing coastal management and conservation strategies in data-poor regions.