Beached plastic and other anthropogenic debris in the inner Seychelles islands: Results of a citizen science approach

Masses of plastic and other anthropogenic debris on beaches of inner Seychelles and derived from 53 organised clean-ups have been analysed. Debris and plastic densities ranged from 0.0011 to 0.1622 kg m⁻² and 0.0004 to 0.1179 kg m⁻², respectively, and data from successive cleans of the same beach resulted in respective median accumulation rates of 0.0293 and 0.0137 g m⁻² d⁻¹. There was no dependence of density or accumulation on beach location/aspect or season, but there were significant inverse relationships with beach area. This effect was attributed to most debris and plastic being trapped on the backshore by rocks and vegetation, and the areal proportion of backshore increasing with decreasing beach size. Plastic is derived from local littering and more distal sources, with polyethylene terephthalate bottles, flip-flops and Styrofoam fragments making important contributions. Without intervention and an increased risk of coastal flooding with climate change, beached debris on Seychelles is predicted to increase.