Hotspots of microplastic pollution found in the North Sea

Marine microplastic pollution is often illustrated by images of wildlife trapped in plastic debris on beaches, highlighting the urgent need for action. However, this widespread pollution goes far beyond what we can see.

Hidden microplastic sinks

Each year, up to 12.7 million tons of plastic enter the ocean through rivers, fishing, aquaculture, and shipping, posing serious threats to marine ecosystems and human health.

While the amount of floating plastic is much lower than expected, it indicates the presence of unseen sinks where microplastics accumulate.

Recent research has identified one such sink in the North Sea. In 2022, Dr. Danja Hoehn and colleagues at the Center for Environment, Fisheries and Aquaculture Science collected microplastic data using a specialized Neuston Microplastic Catamaran.

This floating catamaran, equipped with a mechanical flowmeter and mesh, captured plastics at the ocean’s surface, where microplastics first enter from terrestrial runoff or ship-based sources before sinking to the seabed.

Microplastic crisis in coastal waters

The research is shedding new light on the severity of the plastic pollution in coastal waters.

The data revealed alarming levels of microplastic pollution in coastal areas of the North Sea, particularly in the Southern Bight, where concentrations exceeded 25,000 microplastic items per square kilometer. This region recorded some of the highest levels compared to other nearby areas.

On average, the waters of the Southern Bight contained around 8,700 microplastic items per square kilometer, which is significantly higher than nearby offshore areas.

Off the Scottish coast, microplastic concentrations averaged 4,500 items per square kilometer, while the northeast Atlantic had an average of 3,200 items per square kilometer.

Identifying the microplastic particles

Most of these microplastics were fragments of everyday materials like polyethylene, polypropylene, and polystyrene.

Polyethylene, accounting for 67% of the microplastics found, is commonly used in items such as shopping bags and water bottles.

Polypropylene, at 16%, is used in packaging and textiles, while polystyrene, making up 8%, is found in packaging and disposable medical devices.

Presence of large plastic debris

While the researchers were focused on microplastics, they also uncovered the presence of larger plastic debris. Mesoplastics, measuring 5 to 25 millimeters, and macroplastics, over 25 millimeters, were present but in lower concentrations. 

These larger plastics are often fragments of broken-down materials, including microbeads and plastic film.

Despite a UK ban on microbeads in cosmetics since 2018, their presence in the North Sea suggests they are still being transported by ocean currents from other regions.

Hotspots of microplastic pollution

Hotspots of microplastic pollution were identified near the coast of East Anglia, where concentrations were at their highest.

Despite variations in plastic levels across the study area, the widespread presence of microplastics highlights the ongoing threat they pose to marine ecosystems. The particles can harm marine life through ingestion and entanglement, disrupting entire food webs. 

Currents play a major role in carrying plastic debris into these accumulation zones, with plastics from various countries adding to the problem. 

Interestingly, while the concentrations in the UK’s waters are concerning, they are still lower than those recorded in other parts of the world.

For example, areas off the coast of northwest Spain have been found to contain around 254,000 plastic items per square kilometer, while west Portugal has seen levels around 40,000 items per square kilometer. The Canary Islands recorded a staggering one million items per square kilometer in 2024.

Global action on plastic pollution

Efforts to address this growing issue are underway at both national and international levels. The UK’s Marine Strategy includes plans to develop a microplastics indicator to monitor levels in marine sediments. 

The North-East Atlantic Environmental Strategy also focuses on reducing marine litter in the region. On a broader scale, the United Nations Environmental Agency is working toward a legally binding agreement to end plastic pollution by 2040.

With the global demand for plastic products now exceeding 400 million tons per year, understanding where plastic ends up in our oceans is crucial. 

This research brings us one step closer to uncovering the hidden plastic sinks in our oceans, highlighting the urgent need for action to protect marine life and preserve ocean ecosystems for future generations.

Microplastic threat to marine life

The presence of microplastics in the North Sea not only poses a direct threat to marine life but also disrupts the delicate balance of marine ecosystems. 

As these tiny particles accumulate, they can interfere with the reproductive and feeding behaviors of various marine species. 

For example, filter feeders may ingest microplastics along with their food, leading to harmful health effects and potentially affecting population dynamics. 

Additionally, the presence of microplastics can alter habitat conditions, making it difficult for some species to thrive. 

Understanding these impacts is essential for effective conservation efforts and for safeguarding the health of the ocean environment.

The study is published in the journal Frontiers in Marine Science.

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