Plastic litter persists for many years, is readily dispersed by water and wind, and has been accumulating in the sea for decades. It entangles and is eaten by a wide diversity of aquatic fauna, killing them directly, or reducing their appetite. Concerns about microplastics introducing persistent organic pollutants (POPs) into aquatic food-webs, combined with the discovery of ‘garbage patches’ in all the main ocean gyres, has sparked renewed interest in the subject. This project aims to understand and monitor plastic pollution with a view to reducing the amount entering the environment.

Plastics are used in a plethora of applications because they are lightweight, durable, have excellent barrier properties, and are relatively cheap. These properties also make inappropriately handled waste plastics a serious environmental and economic threat. Although much remains to be learned about the impacts of plastics on aquatic ecosystems, we know enough to act to limit waste plastic entering the environment. 

Reducing plastic pollution depends on changing human behaviour through education, policy interventions, incentives, etc. Knowing where marine plastic comes from, and how it disperses through the environment, is crucial for targeting mitigation measures. Fitz researchers have developed indicators for the levels of environmental plastics that assess the efficacy of measures introduced to reduce plastic leakage. We monitor plastic in the environment through interactions with biota and sampling on beaches. Studies of ‘general’ marine litter, such as bottles and their lids, which could come from a variety of sources, have shown that most foreign drink bottles washing ashore are dumped illegally from ships, whereas most loose lids have drifted from distant land-based sources. 

However, most litter close to urban centres in South Africa comes from local sources. A more applied project has assessed the efficacy of devices designed to trap litter in rivers and storm drains and used spatially explicit models to identify key sites for the installation of litter traps. This project also has a social component, trying to better understand why people litter in different communities across the Cape Flats.
 

Activities in 2025

  • Chukwudi Nwaigwe was awarded his MSc for a study on the amount and composition of litter contributed to beach litter loads by beachgoers. He also assessed the factors influencing surf zone litter in False Bay to assess whether there is significant export of beach litter into the sea. His first chapter, which assesses the use of the ‘wet-dry sand daily accumulation method’ to infer beachgoer contributions to beach litter, will be submitted for publication in early 2026.
  • PhD student Kyle Maclean took a leave of absence to welcome the arrival of his second child, but he made progress with a draft chapter on the attitudes of people from different Cape Town communities to litter and littering.
  • Leo Chini completed his MSc on microfibres in Antarctica sea ice, water and snow using samples collected by Vonica Perold and Eleanor Weideman during the SCALE cruises in 2019. He found higher concentrations of microfibres in sea-ice and snow than in seawater. As is typical in seawater, synthetic microfibres were in the minority, comprising only 14–28% of fibres. Leo has prepared a draft paper that will be submitted in 2026.
  • Emer. Prof. Peter Ryan and Emer. Prof. Coleen Moloney spent a month working with Juan Ceballo-Blanco, a PhD student from Prof. Andres Cózar’s lab at the University of Cádiz, repeating beach litter surveys at 83 South African beaches. These surveys, which started at 50 Cape beaches in 1984, were expanded to include beaches from the west coast to northern KwaZulu-Natal in 1994, and they have been conducted every 10 years since then. The survey, funded jointly by Plastics SA and grants to the University of Cádiz, sampled 61 096 litter items at a median density of 265 items per 100 m of beach. There was a slight decrease in the average density of plastics and most other litter types compared to 2015, but levels remain higher than 1994 or 2005. There has been a steady decrease in the density of ropes and netting since 1994, and numbers of straws and earbuds have roughly halved since 2015, but there has been an ongoing increase in lollipop sticks and plastic fragments throughout the study period. Juan is developing an index to integrate beach litter data into simple, comparable metrics, using OSPAR data, and this survey provided an excellent opportunity to gain firsthand experience of beach litter sampling, as well as to collect data from outside the EU region (the OSPAR Commission is an EU intergovernmental mechanism for protecting the Northeast Atlantic marine environment; its name is based on the Oslo and Paris Conventions). Based on the OSPAR beach litter criteria, six beaches were rated as ‘good’ (< 50 litter items per 100 m of beach), 48 as ‘mediocre’ (50–500 items per 100 m of beach), 17 as ‘unsatisfactory’ (500–1 530 items per 100 m of beach) and 12 as ‘bad’ (> 1 530 items per 100 m of beach). Most of the beaches scored as ‘bad’ were around urban centres, with three around Cape Town, four around East London and three around Durban.
  • Peter also collected data on macro-litter at sea during a cruise from New Zealand to Japan. This repeated a transect conducted in 2023 and indicated that litter densities were six times higher in oceanic waters of the Northern Hemisphere (43 items per 100 km) than the Southern Hemisphere (7 items per 100 km). This will be published once similar data have been collected between New Zealand and Antarctica in early 2026.
  • Peter led on a paper analysing beach litter data collected by Department of Forestry, Fisheries and the Environment (DFFE) personnel on Marion Island over the last 30 years. The paper, which is currently being reviewed, found a decrease in fishing-related litter and foamed polystyrene but an alarming increase in the numbers of plastic bottles, mostly drink bottles, since the mid-2000s.
  • Dr Maëlle Connan (NMU) drafted a paper on the origins of bottles washing ashore on Marion Island, which have shown a marked shift from South America to Asia, mirroring the trend observed at Inaccessible Island in the central South Atlantic Ocean. 
     

Highlights

  • Dr Vonica Perold was awarded a PhD for her study of changes in plastic ingestion by seabirds around southern Africa since the 1980s. She also published the final chapter of her PhD in Environmental Pollution. This paper compared long-term changes in the characteristics of plastics ingested by South Atlantic seabirds with samples collected from selected remote South African beaches since the 1980s. Among plastic fragments, there has been an increase in the proportion of polypropylene relative to polyethylene in both seabirds and beached plastics; the reason for this trend is not known.
  • Abigail Campbell published her CB MSc project on long-term changes in plastic ingestion among White-chinned Petrels Procellaria aequinoctialis since the 1980s in Marine Pollution Bulletin. 
     

Key co-supporters
South African Department of Science and Innovation, through the Waste RDI Roadmap, managed by the Council for Scientific and Industrial Research (CSIR); Commonwealth Litter Programme (CLiP); Plastics SA; United Nations Environment Programme (UNEP).

Research team 2025
Team leaders and collaborators:
Emer. Prof. Peter Ryan (FIAO, UCT)
Emer. Prof. Coleen Moloney (UCT)
Dr Maëlle Connan (NMU) 
Dr Lorien Pichegru (NMU) 
Dr Patrick O’Farrell (UWC) 
Dr Giuseppe Suaria (CNR-ISMAR, Italy)

Students:
Kyle Maclean (PhD, UCT); Chukwudi Nwaigwe (MSc, UCT).