Enormous quantities of marine debris are beaching on the shores of remote islands in the western Indian Ocean, despite negligible local sources of pollution. For instance, over 500 tonnes of debris has accumulated on the shores of Aldabra Atoll, Seychelles, a World Heritage Site with no permanent population. Identifying the sources of debris beaching on these remote islands is challenging as observations are sparse and limited to the subset of beaching debris with provenance indicators such as intact labels. By carrying out a set of large-scale dispersal experiments with plastic sources from coasts, rivers, and fisheries, we have predicted the key sources of marine debris accumulating at remote western Indian Ocean islands. Comparison of our results with observations across Seychelles suggests that debris discarded from shipping traffic passing through the western Indian Ocean may be a major source of debris for remote islands in Seychelles such as Aldabra. Our simulations also suggest that debris accumulation is likely to be strongly seasonal at most islands in the western Indian Ocean, with debris accumulation peaking during the northeast monsoon.
This study (along with associated data and scripts) was published in Marine Pollution Bulletin.