The ‘shellfless’ work of bivalves for UK water quality. What if improving water quality and producing sustainable seafood could go hand in hand?

That’s the idea behind new research from our ecosystem services researcher, Konstancja Woźniacka, in her latest report ‘Nutrient Removal by UK Bivalve Aquaculture: Case Studies and Considerations’.

Building on Konstancja’s earlier work from 2022, this new study explores how shellfish farming could play a practical role in tackling one of the UK’s biggest environmental challenges: excess nutrients in our waters.

In this blog, Konstancja describes the important and often undervalued role bivalves play in the underwater filtering process, helping to keep our waters healthy and clear and supporting local communities.

Why this matters now

Nutrient pollution, particularly nitrogen and phosphorus, remains a costly and complex issue across the UK.

While nutrients are essential components of life, in excess they can trigger eutrophication, affect ecosystems and water quality, and create knock-on impacts for industries and coastal communities.

Significant investment is already being made to address this. Water companies are spending hundreds of millions on infrastructure and treatment upgrades. But increasingly, there’s recognition that traditional approaches alone won’t solve the problem.

Nature-based solutions are gaining attention – and that’s where bivalves come in.

The role of bivalves

Bivalve shellfish like mussels, oysters and clams are natural filter feeders. By consuming algae, they remove nutrients from the water and mitigate eutrophication as part of their normal feeding process.

When farmed at scale, this natural function can contribute to reducing nutrient levels while also producing low-impact, nutritious food.

Beyond water quality, bivalve aquaculture can also:

• Support biodiversity
• Help recovery of seabed habitats
• Increase the abundance of marine life

Bivalve aquaculture is not a ‘fix-it-all’ solution to the problem of excess nutrients, but they can support traditional approaches, especially in areas experiencing eutrophication.

What this report looks at

This latest research focuses on real-world UK case studies, examining different types of shellfish farms across a range of environments.

It looks at:

• How different farming approaches and species, including blue mussels, native oysters and Pacific oysters influence nutrient removal.
• The potential monetary value of these environmental benefits.
• How shellfish aquaculture could fit into wider nutrient management strategies, drawing on international expertise from the UK, Europe, North America and Australia.

Key takeaways

A few standout insights from the research:

• Shellfish farming can support existing solutions: It won’t replace traditional nutrient reduction approaches, but it can complement them, especially in areas affected by eutrophication.
• There is real economic value: Nitrogen (127 – 286 tonnes) removal by the UK shellfish sector in 2019 was estimated to be worth between £7 million and £16 million, compared to traditional water treatment methods.
• Scale matters: Larger farms, particularly mussel farms, tend to remove more nutrients. The overall impact is closely linked to production levels.
• Different species, different impact: Not all shellfish remove nutrients equally, meaning species choice and farming approach both matter.
• It doesn’t affect food safety: Shellfish remain safe, nutritious, and marketable while delivering these environmental benefits.
• The estimates of removal and value are variable and will depend on harvest level, species, cultivation methods, and the alternative cost used for comparison. 

Who should read this?

This report is relevant for:

• Shellfish growers and aquaculture businesses
• Environmental regulators and policymakers
• Researchers and environmental organisations
• Anyone interested in nutrient markets or nature-based solutions

Whether you’re shaping policy, managing coastal environments, or working in seafood production, the findings highlight new opportunities and important considerations.

So what happens next?

There’s growing global interest in using shellfish as part of nutrient management strategies, embracing sustainable solutions and expanding natural processes in the sea. The UK is well placed to explore this further.

But making it work in practice will require:

• Clear and standardised methods for measuring nutrient removal
• Practical and fair systems for valuing and trading these benefits
• Strong communication to build public understanding and confidence

Most importantly, this approach needs to sit alongside, not replace, efforts to reduce pollution at source.

Find out more

This blog is just an introduction. The full report explores the case studies, methods and an overview of practicalities for including bivalve aquaculture in nutrient management.

Seafish conducted this work with support from researchers at Agri-Food and Biosciences Institute (AFBI), Longline Environment Ltd and Suzanne Bricker (NOAA, retired).

Image: Seafish

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