Proximity to coast and major rivers influence the density of floating microplastics and other litter in east African coastal waters

Floating anthropogenic litter occurs in all ocean basins, yet little is known about their distribution and abundance in the coastal waters off east Africa. Neuston net and bulk water sampling shows that meso- and microlitter (8567 +/- 19,684 items center dot km- 2, 44 +/- 195 g center dot km- 2) and microfibres (2.4 +/- 2.6 fibres center dot L- 1) are pervasive pollutants off the coasts of Tanzania and northern Mozambique, with higher litter loads off Tanzania. Densities of meso- and micro-litter at the start of the rainy season were greater close to the coast and to major river mouths, suggesting that much litter likely originates on land. However, the mass of litter increased with distance from the six major coastal cities. By number, 95% of meso- and micro-litter was plastic, but only 6% of microfibres. Our results highlight the need to reduce plastic use and improve solid waste management in the region.

Automated summary

Little is known about the distribution and abundance of floating anthropogenic litter in the coastal waters off east Africa. A study shows that meso- and microlitter, as well as microfibres, are pervasive pollutants in Tanzania and northern Mozambique. The majority of the litter originates on land, highlighting the need to improve solid waste management in the region.