Debris size and buoyancy influence the dispersal distance of stranded litter

Recent at sea surveys of floating macro-debris in the southeast Atlantic Ocean found that debris increases in size with distance from shore, suggesting that many smaller items, which dominate litter close to urban source areas, sink before dispersing far into the ocean. We test whether this pattern...

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Bibliographic Details
Published in:Marine pollution bulletin 2016-09, Vol.110 (1), p.371-377
Main Authors: Fazey, Francesca M.C., Ryan, Peter G.
Format: Article
Language:English
Subjects:
Atlantic Ocean
Bathing Beaches
Biofouling
Brackish
Dispersal
Environmental Monitoring - methods
Flotation
Marine
Marine debris
Microplastics
Plastics - analysis
Size
South Africa
South Atlantic
surveys
Waste Products - analysis
Water Pollutants, Chemical - analysis
water pollution
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Summary:Recent at sea surveys of floating macro-debris in the southeast Atlantic Ocean found that debris increases in size with distance from shore, suggesting that many smaller items, which dominate litter close to urban source areas, sink before dispersing far into the ocean. We test whether this pattern is evident in beach litter in the same region. Freshly stranded beach litter was collected at increasing distances (0km, 100km, 200km and 2800km) from Cape Town, a major urban litter source. Mean size and buoyancy of litter items increased significantly with distance from Cape Town. Size-specific sedimentation due to the ballasting effect of biofouling is a plausible explanation for the disappearance of smaller, less buoyant items. Our results provide further evidence that many low buoyancy items sink and support the hypothesis that size and buoyancy are strong predictors of dispersal distance for floating debris. •Beach litter size and buoyancy increases with increased distance from pollution sources.•This reflects trends found in floating litter in the same region (southeast Atlantic Ocean).•The effect was evident over a distance of 200km.•Our results suggest that many smaller plastic items fail to disperse long distances.•Size-specific sedimentation due to biofouling is a plausible explanation for these trends.
ISSN:0025-326X
1879-3363
DOI:10.1016/j.marpolbul.2016.06.039