From Indonesia to the Southern Ocean: Marion Island’s growing plastic problem

One of the most remote islands on Earth is not escaping the tide of global plastic pollution.

A 30-year study of beach litter on the sub-Antarctic Marion Island shows that while waste generated by the island’s research station has fallen sharply, thanks to improved management, plastic debris drifting in from the ocean is steadily increasing.

This includes drink bottles and bottle caps that might have travelled thousands of kilometres across the Indian Ocean.

The long-term research, led by scientists from the FitzPatrick Institute of African Ornithology at the University of Cape Town, tracked litter washing up on beaches around the windswept island, which lies about 2 000km south-east of South Africa in the Southern Ocean. 

Marion Island is afforded the highest level of conservation protection under South African law, yet the findings show that no location, however remote, is immune to plastic pollution.

The study, published in Marine Pollution Bulletin, was led by UCT Emeritus Professor Peter Ryan, in collaboration with researchers from Nelson Mandela University and the department of forestry, fisheries and the environment.

“A study on the origins of these bottles is still under review but we know from studies in other parts of the Southern Hemisphere that most plastic bottles washing up on remote islands have been dumped from ships in contravention of international legislation,” Ryan said.

“The study highlights the recent increase in floating plastic litter, especially plastic bottles, in even the remote and hitherto largely litter-free Southern Ocean.” 

The findings, he added, placed yet more pressure on the International Maritime Organisation to strengthen measures to ensure that ship crews stopped dumping plastics and other persistent wastes at sea.

Over the three decades, scientists found that most of the debris did not originate on Marion Island. Only about 5% of litter came from local, land-based sources, with the rest arriving from offshore. Plastic dominated offshore debris because it is lightweight, durable and capable of floating across large distances.

Between May 1993 and April 2024, the researchers recorded 7 298 litter items on Marion Island beaches, at an average accumulation rate of 243 items a year. Of all litter, 91% was plastic, including 17% foamed plastics, while smaller amounts were wood, metal, glass, rubber and other materials. 

Local litter, by contrast, was mostly heavier materials: plastic made up only 32%, with wood (32%) and metal (22%) more common. All paper, cardboard and paint flakes were traced to on-island activity. 

Offshore litter was 94% plastic, showing the dominance of long-lasting materials transported across the ocean. More than half of all items were bottles or containers (58%), almost all of them plastic.

The highest concentrations of debris were found on the island’s west-facing beaches, exposed to prevailing westerly winds that push floating litter ashore. The authors noted that similar patterns had been documented on other sub-Antarctic islands and parts of the Antarctic Peninsula.

One of the study’s most intriguing findings was a consistent spike in litter arrivals during late winter, which was observed in all three decades. 

The authors suggested that winter storms might push floating debris onto beaches and transport litter south from more northern parts of the Indian Ocean. Seasonal fishing activity might also contribute, although the study could not link individual litter events to specific vessels or storms.

While offshore debris has increased, locally generated waste has declined dramatically. Marion Island hosts a South African research station, with 15 to 25 people present year-round and up to 100 during annual supply voyages. 

In earlier decades, supplies were transported in wooden crates and packaging materials, some of which escaped into the environment. The island experiences gales on more than 100 days a year, easily blowing loose debris into the sea.

Significant improvements to waste management began in the mid-1990s. The Prince Edward Islands management plan required managers to minimise waste, avoid plastic packaging and return all non-biodegradable materials to South Africa. Polystyrene packing was banned and burnable waste incinerated in enclosed facilities. When a new research station opened in 2011, incineration was stopped and all non-biodegradable waste had to be removed.

“These measures, together with increased awareness of the need to avoid littering, account for the decrease in beach litter from local sources,” the study said. “Currently, the few local litter items found each year typically come from equipment lost in the field or storm damage.”

Offshore debris tells a different story. Plastic bottles and lids have increased markedly over the past 15 to 20 years, even as fishing gear has declined since the collapse of the Patagonian toothfish fishery in the late 1990s. 

The study noted that while the abundance of foamed polystyrene had declined since the 1990s, the findings “indicate a worrying increase in general plastic waste at sea in the Indian Ocean sector of the Southern Ocean over the last 20 years”. 

“This increase is consistent with the increase in plastic items in the regurgitations of grey-headed albatrosses and giant petrels breeding on Marion Island over this period. Most drink bottles probably are dumped illegally from ships at sea, given findings from other remote islands in the Southern Hemisphere and from the South African coast and this conclusion is supported by data on the origins and ages of bottles.”

The study noted that there had been an increase in the numbers of bottle lids washing ashore on Marion Island beaches, mirroring an increase in lids in albatross regurgitations. 

“Most lids that could be identified in seabird regurgitations came from Indonesia, as was the case for foreign lids on South African beaches, indicating long-distance drift across the Indian Ocean.”

The researchers emphasised that reducing offshore litter on Marion Island would require stricter enforcement of international dumping bans and coordinated efforts to curb land-based plastic pollution, particularly in Southeast Asia.