Nurdle drifters around South Africa as indicators of ocean structures and dispersion

• DOI: 10.17159/sajs.2019/5372
• Publication Date: 2019-05-28T12:25:14Z
• Authors: Eckart H. Schumann; C. Fiona MacKay; Nadine A. Strydom
• Keywords: H1-99; Science (General); dispersion processes; Science; Q; Social Sciences; larval movement; 01 natural sciences; Social sciences (General); Q1-390; H; 13. Climate action; microplastic pollution; wind; 14. Life underwater; currents; 0105 earth and related environmental sciences

Dispersion processes in the ocean typically involve wind, currents and waves. All these factors were included an analysis to model nurdle dispersion from accidental spill Durban Harbour, South Africa, October 2017. Nurdle sightings on beaches by members of public are used as indicators which extended over 2000 km African coastline a period 8 weeks. Using known oceanographic current structures, satellite imagery, wave data surface wind drift values between 5% 8% speed, good agreement was found modelled sightings. In particular, it that nurdles remained specific sections coast for long periods, sporadic events required move them into new coastal areas. Such results may also contribute understanding dispersal behaviours strategies adopted larval stages marine organisms, particularly fishes, have pelagic durations extend weeks months. The event recognised major pollution incident rivalling other spillages reported worldwide, extensive efforts made collect nurdles, along northern KwaZulu-Natal coast. However, 9 months later, less than 20% had been recovered. emphasise connectivity different regions, particular is not localised activity. Matter discharged at one point will disperse wide area – this case, significantly further afield recovery operations. Significance: Wind upper metre or two has notoriously difficult quantify, spread can only be explained using percentages three times generally accepted value 3% less. Nonetheless, important realise there substantial differences rates few centimetres even deeper. rapid manner microplastics, dispersed terms form world’s oceans. confirm role play movement eggs, larvae invertebrates significance vertical migrations out layers.