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What Lies on Land May Not Lie Beneath

Difference between the debris found on beach and the debris found under water may surprise you

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© PADI/Project Aware

This blog was written by Jenna Schwerzmann. Originally from upstate New York, Jenna began her marine conservation career on Long Island after graduating from Stony Brook University with a B.S. in Marine Vertebrate Biology and M.A. in Marine Conservation and Policy. She has experience with both research and outreach for local estuarine conservation efforts, including horseshoe crab monitoring, shellfish restoration and water quality projects, all through Cornell Cooperative Extension’s Marine Program. Jenna has also volunteered aboard whale watches since 2015 and interned at NOAA Fisheries in Gloucester, Massachussets to assist with outreach for the Whale SENSE Program.

Plastic pollution has emerged in all kinds of unexpected places: it has turned up in the deepest parts of the ocean, throughout the Arctic seas and even in our salt shakers. But have you ever wondered whether the debris found underwater is the same as that found on the beach? Well, if you answered yes, then we’ve got the data for you. Together with our long-time partner, Project Aware, and Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, Ocean Conservancy recently published an analysis of historical data from our International Coastal Cleanup (ICC) and Project Aware’s Dive Against Debris (DAD).

The study compared debris from underwater cleanups with debris collected on beaches within the same region. Across the globe, 437 regions were analyzed comprising a total of 19,428 land-based or underwater cleanup surveys that took place between 2011 and 2018, distributed across 86 countries.  Through this research, the authors discovered an overall mismatch between what’s collected on land and what’s found on the seafloor.

The analysis showed that while beaches and the seafloor shared many of the same items of marine debris, they varied in proportions. In other words, the debris that showed up in high numbers on the beach were less prevalent in the sea, and vice versa. This difference suggests that once debris enters the marine system, items that sink tend to end up on the seafloor and stay there. Items that are lightweight—like cigarette butts and food wrappers—can, unfortunately, travel easily in the wind or down storm drains, and may be transported away from the coast.

While proportions differed, ten items were present in both terrestrial and aquatic environments across regions. Seven out of those ten items were single-use packaging products—four attributed to the beverage industry—while two others were tied to specific activities: smoking and fishing.

DSC07051_2019_ICC_SantaMonica_47_PC Emily Brauner
© Emily Brauner

I asked Hannah Pragnell-Raasch, the Policy Lead for Project Aware, if she was surprised by these results. While she expected a mismatch from what she has seen herself while cleaning up debris with “fins on” or “fins off,” she said, “it was cool to see that reflected in empirical data.” This data is also the first of its kind on a global scale, which would be impossible to attain without the help of volunteers. “Citizen science data can help increase our knowledge and understanding of the fate of marine debris in the environment,” said Hannah. “Having these peer-reviewed publications has been a real milestone.

Both plastic bags and lost or abandoned fishing gear, including fishing line, are among the top five deadliest forms of marine debris to marine wildlife. It is troubling that these items are similarly prevalent on shorelines as well as in coastal waters, where the majority of marine organisms make their home. Equipped with this new knowledge, we now know that efforts to reduce fishing line or plastic bag pollution will not just help keep our beaches clean, but also reduce debris on our reefs, sea floor and in surrounding waters. This valuable information is made possible through the collaboration of cleanup efforts from programs like International Coastal Cleanup, Global Ghost Gear Initiative, Project Aware, and our partners and volunteers.

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© Troy Mayne

No one is going to solve the problem of marine debris on their own,” Hannah said. “That collaboration is really important, so this is a nice example of how two NGO’s and a research organization can work together to move that conservation needle forward and hopefully impose change.

As we work to reduce plastic pollution at the source, the continued efforts by our passionate, dedicated cleanup volunteers and partners around the world keep our beaches, waterways and underwater habitats clean, and generate critical information to inform management and policy decisions.  Furthermore, every volunteer that participates in the International Coastal Cleanup and Dive Against Debris proves that every piece truly matters.

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