Are tropical mangroves a sink for litter leaking from land-and sea-based sources? Evidence from selected Kenyan mangroves

Marine litter surveys were carried out to determine the role of mangroves as a sink for litter. General litter density in the mangroves was 0.088 ± 0.076 items m^-2, composed mainly of plastic (85.9 %). Higher litter densities occurred in the middle (0.162 ± 0.150 items m^-2) compared to the landward (0.066 ± 0.049 items m^-2) and the seaward zones (0.036 ± 0.028 items m^-2), indicating the important role played by the middle zone in providing a sink for litter from both land and sea-based sources. Landward zones were a sink for heavier litter from land that could easily be trapped by mangrove roots (plastic and clothing). The middle zones retained mainly the litter that are not easily trapped by the mangroves' roots in seaward and landward zones, particularly soft plastics. The seaward zones acted as a sink for litter from sea-based sources mainly marine and fishing gears, and materials used for fishing and boat repairs.