Replication Data for "High abundance of macroplastic on a sea turtle nesting beach at the Pacific coast of Central America"

Abstract of Manuscript: 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 (> 5mm) pollution on an Olive Ridley (Lepidochelys olivacea) nesting beach along the Pacific coast of Guatemala by applying both unmanned aerial vehicle (UAV) surveys and ground-based monitoring. We mapped macroplastic items using the OSPAR (Oslo and Paris Convention) beach litter protocol for both UAV imagery and systematic ground-truthing within representative grids. 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 2,102 items per 100m shoreline, exceeding the OSPAR beach litter threshold 100 times. Most 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 consistently detected substantially 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. 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.