Citizen science derived spatiotemporal (2020-2025) microplastic accumulation data for Tortuga Bay, Galápagos Islands

This dataset documents the spatiotemporal accumulation of beach microplastics (>1 mm) on Tortuga Bay, Santa Cruz, Galápagos Islands. Suspected particles (3,377) were collected using a simple citizen science methodology which employed a standard unit (50 x 50 cm quadrat), sampled to a standardised depth (5 cm) at a known location (strandline or turtle nesting zone) and time (2020 to 2025). Attenuated Total Reflectance Fourier-transform Infrared (ATR-FTIR) spectroscopy, evaluated against a hand-held near-infrared (NIR) spectrometer (PlasTell), verified that 92.77% of particles had been correctly identified by citizen scientists (local teenagers from the Molas Ecology Club of ECOS - Educación para Comunidades Sostenibles) as plastic, with a mean concentration of 145.29 ± 23.57 particles m^-2, primarily low density polyethylene (72.51%) and polypropylene (22.44%) fragments. Microplastic accumulation increased temporally in 2024 (290.88 ± 73.76 particles m^-2) coinciding with the El Niño-Southern Oscillation in the Pacific Ocean, as well as spatially at the turtle nesting zone at the back of the beach, with elevated composition of preproduction pellets 'nurdles' (234.59 ± 42.25 particles m^-2; 22.54% respectively). This data demonstrates how technology-aided citizen science approaches can support regional monitoring capabilities across environmentally dynamic and remote island systems. This work forms part of the Pacific Plastic: Science to Solutions network, funded by Global Challenges Research Fund (GCRF) grant 'Reducing the impacts of plastic waste in the Eastern Pacific Ocean' (NERC grant reference NE/V005448/1).