Type to search

Marine Science



Citizen scientists contribute to environmental research. Ahead of the Global Citizens Assembly at COP26 in Glasgow, a team of international researchers is calling attention to a ground-breaking report on the sources of marine pollution as an example of the powerful role citizen scientists can play in finding solutions to complex environmental problems.

In the first study of its kind, a team of researchers drew on a sweeping data set obtained from the Ocean Conservancy’s International Coastal Clean-up and the PADI AWARE Foundation™’s Dive Against Debris® programmes to identify socioeconomic and geographic factors related to coastal and seafloor pollution.

“This research could not have been done without the information collected by hundreds of thousands of citizen scientists conducting tens of thousands of clean-ups world-wide,” said Dr. Denise Hardesty, a Senior Research Scientist at CSIRO, Australia’s National Science agency and a leader on the study.

The findings provide some of the most detailed information available on sources and patterns of pollution in scores of countries around the world, and could inform strategies to protect marine life and habitats from pollution — a critical tool at a time when the ocean faces unprecedented pressures from climate change, overfishing, and other threats.

“Hotspots of plastic pollution also reflect the patterns of local deposition, waste management and accumulation,” Hardesty continued. “By identifying these locations using real data, local decision makers can assess opportunities on where and how to implement effective policies to reduce plastic in the environment.”

The research also upends some of the conventional wisdom on pollution. Contrary to a prevailing view that plastic pollution is largely a problem for the Global South, it found plastic pollution hotspots exist globally and in a wide variety of socioeconomic contexts.

The analysis used comprehensive data obtained from 22,508 land-based clean-ups as part of Ocean Conservancy’s International Coastal Clean-up across 118 countries (2011-2017) and 7,290 seafloor clean-ups conducted through the PADI AWARE Foundation’s Dive Against Debris programme in 116 countries (2011-2018).


  • The 10 most abundant items on land (in order ranked 1-10) included cigarette butts, food wrappers, plastic beverage bottles, plastic bottle caps, plastic bags, plastic straws, plastic take-away containers, plastic lids, and foam take-away containers and plastic pieces (fragments).
  • The ten most common items found on the seafloor included (in order from 1-10) fishing line, plastic pieces, glass bottles, plastic beverage bottles, food wrappers, metal cans, plastic bags, fishing gear, plastic cutlery, and rope.
  • Hotspots of individual litter items, such as cigarette butts or food wrappers, were differentially driven by socioeconomic factors. For example, a positive correlation between cigarette butts and national wealth was found.
  • The study found that where local population increases, single use-packaging such as takeaway food and beverage containers also increases.
  • Hotspots for fishing line occurred in Australia, UK and USA, where recreational fishing is a common pastime.
  • Mass transit hubs, like train stations, are often hubs for single-use food and beverage packaging, but not items with recycling value.

Dr. George Leonard, Chief Scientist at Ocean Conservancy

“Given the sheer volume of single-use packaging items recorded, changing the way we use and dispose of these items will likely substantially reduce the amount of litter found on land, in our waterways, and on the bottom of the ocean. Our research highlights the need for local policies and actions targeted to reduce plastic pollution, before it gets into the environment. Our study makes a strong case that beach and underwater clean-ups provide critical, complementary data about the extent of plastic pollution in the environment.”

Ian Campbell, Associate Director, Policy and Campaign for PADI AWARE FOUNDATION

“Litter that is found on land is not a reliable indicator for seafloor debris and vice versa, as different factors influence where and what types of debris are found on land and on the seafloor, although some items are common to both. We found that some seafloor debris hotspots were associated with partially landlocked seas.”