Stanford
Center for Ocean Solutions

Sand dredging encroaches on marine protected areas, scientists find

Nearly half of all dredge operators extract sand from protected areas of the ocean, highlighting the need to mitigate demand for the world’s most mined material.
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Katie Jewett
Specialized dredgers transport ocean sand through "rainbowing," a method that pumps sand from the sea floor and sprays it through the air to a new, desired location. Image credit: iStock/Wouth

Every day, several thousand dredge operators scrape the seafloor for sand in what scientists say is an overlooked threat to marine biodiversity. Increased demand for sand has incentivized dredge operators to expand into new areas of the ocean, including regions set aside for conservation known as marine protected areas. 

According to one of two commentaries published in One Earth in Feb. 2025, nearly half of all dredge operators mine sand and other sediments from marine protected areas at some point during the year, highlighting the need to increase regulatory oversight and reduce demand for sand.

“Sand is a critical component of the coastal and marine environment, supporting a wide variety of habitats and species while delivering key ecosystem services like water filtration, nutrient cycling, and pollutant degradation,” said Jean-Baptiste Jouffray, a Wallenberg Postdoctoral Fellow at the Center for Ocean Solutions and the Natural Capital Project in the Stanford Woods Institute for the Environment who co-authored both studies. “Left unchecked, sand extraction poses a significant threat to conservation.”

Sand is the second most used natural resource on Earth, and an essential component of many modern conveniences like concrete, glass, cell phones, and cosmetics. However, unlike ocean sand, most desert sand on land isn’t suitable for commercial use or construction.

 Related: Ask a scientist: Ocean sand

Putting sand on the ocean sustainability agenda

Dredging alters the seafloor by emitting huge plumes of sediment that disrupt nutrient cycles and smother marine life like sea grasses and corals. It can also reshape natural features like beaches and dunes that protect coastal communities from severe storms and sea level rise. A 2023 report led by Jouffray highlights the social and environmental costs of ocean sand mining and opportunities to strengthen regulatory oversight through global policy mechanisms. (Image credit: #SaveMaldives Campaign @ savemaldives.net)

Read the report

One of the studies, led by Aurora Torres at the University of Alicante in Spain, used data from the Marine Sand Watch, a global monitoring platform launched in 2023 by the UN Environment Program’s GRID-Geneva partnership, to see whether dredgers operated inside the boundaries of a marine protected area. Not all marine protected areas ban or restrict sand mining, so the presence of dredging did not necessarily indicate illegal activity, but rather areas where sand extraction and rich biodiversity overlap.

The study found concentrated dredging activity along the U.S. East Coast, the African West Coast, in the Persian Gulf, the North and Baltic Seas, and across East Asia. The study’s authors could only obtain data from 60% of the world’s dredging fleet, suggesting that the geographic reach of ocean sand extraction exceeds current estimates. 

“Making sand extraction visible—through stronger data, improved governance, and clear links to environmental and economic concerns—is crucial. The more tangible its impacts become, the harder it will be to ignore the need for responsible management,” said Torres.

From sand crisis to sand sufficiency

Balancing sand extraction with natural replenishment will require a significant reduction in global demand. But this is a tall order. Sand is ubiquitous in human-made materials, which according to a 2020 Nature study, exceeds all living biomass on Earth.

On the left, a sand pile branches out into categories such as concrete, bricks, asphalt, metals, and others. Each category describes how sand contributes to the material’s properties. On the right, two bar-like structures compare anthropogenic mass (1,154 Gt) and living biomass (1,120 Gt). The anthropogenic mass is broken down into stacked segments corresponding to the material categories. The living biomass column shows mostly plants, a tiny fraction of animals, and a smaller fraction of humans.
In this figure, Pereira and team illustrate the ubiquity of sand in materials used to manufacture human-made structures, which now exceed all living biomass on Earth. Each block represents one gigaton. (Figure credit: Pereira et al. 2025, estimates derived from Elhacham et al. 2020)

In a second commentary led by Kiran Pereira at the Stockholm Resilience Centre, the authors suggest moving beyond the “take-make-dispose” approach to construction materials, like concrete and glass, that include sand. The construction sector accounts for as much as 65% of landfill waste, and up to 30% of materials are damaged before arrival at building sites.

Resources like the book Re-Use Atlas explore how the construction industry can move from a linear to a circular economy through many inspirational case studies. “While extending the life of materials manufactured with sand is important, it’s also imperative to rethink how much sand we use in the first place,” said Pereira. 

It’s more than just modern conveniences at stake. “Millions of people around the world rely on ocean sand for stable coastlines, livelihoods, and cultural heritage,” said Colette Wabnitz, a co-author of the second commentary and lead scientist at the Center for Ocean Solutions. “Regulatory processes must include the communities most affected by sand extraction in order to work towards greater sand sufficiency and a more sustainable and just future.”

Jouffray is also affiliated with the Stanford King Center on Global Development and the Stockholm Resilience Centre in Sweden. Wabnitz is also affiliated with the Institute for the Oceans and Fisheries at the University of British Columbia in Canada.

Other co-authors are affiliated with Ghent University and the Institute of Natural Sciences in Belgium, Michigan State University, the Royal Swedish Academy of Sciences, the University of California Santa Barbara, the University of Geneva in Switzerland, and the University of Leeds in the UK.

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