Accumulation and characteristics of plastic debris along five beaches in Cape Town.

Beach accumulation surveys can be used as a proxy to estimate litter flows into the marine environment. However, litter loads can be influenced by various factors including catchment area characteristics, weather conditions and ocean water movements. This complexity is evidenced by the results of five beach surveys conducted in Cape Town in 2017. Observed average litter accumulation rates across the beaches ranged from 36 to 2961 items·day·100 m. Item mass ranged from 0.01-367 g, with items weighing <1 g contributing 61-85% of count. Plastic items accounted for 94.5-98.9% of total count and this prevalence appears to have increased relative to older data (1989-1994). The top ten identifiable items accounted for 40-57% of plastic debris. Nine of these were associated with foods commonly consumed on-the-go, including polystyrene packaging, snack packets and straws. A mitigation approach focused on these items may address one third to one half of marine litter sources in Cape Town.