Ocean cleaners can also capture marine organisms

Every year, more than 14 million tons of plastic pollute the ocean and threaten the lives of various marine species. About 80 percent of all marine litter is plastic, showing the scale of global plastic pollution.

Boat builders, sailors and engineers have developed technological innovations such as the Seabin or Mr. Trash Wheel to minimize all types of waste floating in the ocean. These mechanical cleaning inventions are fixed point devices designed to separate and remove marine debris from various bodies of water. They work by suctioning water from the surface and catching floating debris or lifting trash out of the water onto a conveyor belt that collects everything in a dumpster.

However, they may be of limited benefit in reducing plastic pollution. Research has shown that the devices can even capture unknown marine organisms, which is a problem as they threaten marine life.

The rate of waste generation exceeds the rate of waste clearance

Recently Marine Pollution Bulletin study examined a Seabin in the south-west of the UK and found that it captured an average of 58 litters per day, consisting mainly of polystyrene balls, plastic pellets and plastic fragments. The authors also found that the device caught one marine organism—such as sand eels, brown shrimp, and crabs—for every 3.6 items of debris caught (or roughly 13 marine organisms per day), half of which were dead during retrieval.

Marine organisms may be attracted to the device to search for food or seek shelter. Their mortality also seems to increase with time spent in the machine. Some died because they were caught, possibly under the weight of the surrounding material, said Florence Parker-Jird, a study author and research associate at the International Marine Debris Research Unit at the University of Plymouth in the United Kingdom.

“At this stage of development, the study found that in the environment studied, the amount or mass of waste removed by the device is minimal when considered together with the risk of bycatch,” says Parker-Jird. She adds that manual cleanup efforts with pontoon nets are generally more efficient and require fewer resources than Seabin in environments such as marinas, harbors and ports, even though it is designed to work in those locations.

“Technological innovations have a role to play in reducing marine litter, particularly in coastal environments where they can complement existing clean-up efforts,” says Parker-Jird. “This study highlighted the need for robust, formal assessments of such devices, particularly given the increasing use and geographic spread of Seabin and similar devices.”

[Related: A close look at the Great Pacific Garbage Patch reveals a common culprit.]

Although the study formally evaluated only one device, similar issues may apply to other marine cleaning devices. Things like the lack of an escape route, long periods of work and time out of the water to separate marine life from organic matter and debris before returning to the water can contribute to the entrapment of marine organisms, Parker-Jird says.

Furthermore, the current capacity of technological efforts to reduce plastic collection is limited relative to the scale of the plastic pollution problem. “Although there are no estimates of the total removal of plastic and other waste from these devices, there is a near consensus among experts that the amount of trash collected pales in comparison to the amount of waste that enters our environment,” says Megan Dunphy-Daly, director of Duke University Marine Laboratory Scholars Program. She did not participate in the research.

There isn’t much scientific research on the effectiveness of different technologies in removing plastic pollution from the environment — or their bycatch rates in the sea — but self-reported effectiveness is often higher than peer-reviewed efficacy reports, Dunphy-Daley says. Time, current, and location of device deployment must be considered when it comes to the effectiveness of cleaning technologies beyond their pilot phases.

The Dutch non-profit organization The Ocean Cleanup has come under fire recently for a pile of plastic waste they cleaned up the Great Pacific Garbage Patch, which some experts say is too clean for plastics that are supposed to have been in the water for years. The organization claims there is no visible build-up of algae and crustaceans because the water in the trash contains no nutrients. Most of the plastic floated above the water, but conservation experts also refuted that.

“Further studies should evaluate the types of marine life that are captured in these devices to determine population-level effects and weigh the risks and benefits of using these cleanup technologies,” says Dunphy-Daley.

Technology must go hand in hand with reducing the production and use of plastic

Developing and implementing waste reduction technologies is only part of the solution. When there’s an oil spill, you don’t just focus on removing the oil from the surface of the water—you stop the leak and clean it up, says Dunphy-Daly.

Leakage has undoubtedly continued in the case of global plastic pollution. She adds that combating it requires a holistic approach that addresses all stages of the plastic life cycle, from reducing overall production to cleaning up what has entered the environment.

However, the invention of cleaning devices effectively drew attention to the problem of marine litter. Last year, Coldplay partnered with The Ocean Cleanup and sponsored the Interceptor, a vessel or vessel designed to remove plastic from rivers before it reaches the ocean.

[Related: Horrific blobs of ‘plastitar’ are gunking up Atlantic beaches.]

“We hope that by generating public interest in these technologies, we can also gain support for targeting other plastic life stages and reduce overall plastic pollution,” says Dunphy-Daly.

A 2021 report by the National Academies of Sciences, Engineering, and Medicine argues that recycling processes and infrastructures are insufficient to manage the gross amount of plastic waste produced. The authors recommend several interventions to reduce waste generation, such as establishing a national limit on clean plastic production and banning specific single-use plastic products.

Mechanical marine cleaning devices can shape perceptions around the marine litter problem and potentially create dependence on technological solutions to environmental problems. Therefore, these types of interventions should continue to be evaluated, Parker-Jurd says. According to 2022 Societies paper, there is excessive optimism surrounding technology and scientific progress. Yet, the planet’s man-made problems cannot be solved by modern and efficient technologies alone.

Although the invention of cleaning devices is unlikely to completely alleviate the responsibility for waste and litter, evidence of their psychological impact is currently lacking and should still form a crucial part of future research, Parker-Jird says. She adds, “our main focus must remain on implementing systemic change in the way we produce, use and dispose of plastics.”

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