Bivalves: More Than Meets the Shell

By Konstancja Woźniacka

Since the start of the year, I’ve had the pleasure of attending two major marine-focused conferences: OCF 2025, centred on marine environment conservation, and NASF 2025, highlighting aquaculture’s role in sustainable food production. Both were incredible opportunities to step out of my little comfort zone of the shellfish world, like a brave little hermit crab, and broaden my horizons, explore how we govern our seas, use their resources, and connect with oceans on a global scale. Still, I couldn’t help but look out for all the bivalve-friendly content that really gets me excited. For those less familiar, bivalves—think mussels, oysters, clams, and scallops—are filter-feeding mollusc with two hinged shells. I know I’m not alone in championing them.

The UK’s shellfish community is growing, and more effort goes into encouraging consumers to give these little creatures a chance to come out of their shells and wow them. Conferences like ASSG in Oban and SAGB in London are fantastic spaces to celebrate the sector, but I’d love to see shellfish in the spotlight beyond these designated events — discussed at coastal management forums, aquaculture meetings, and anywhere we’re planning the future of our oceans. Because bivalve aquaculture nestles beautifully in both of these worlds.

This focus on bivalves isn’t just a passing interest for me—it’s what I do every day. I’m an Ecosystem Services researcher at Seafish, focusing on the ecosystem services of commercially important bivalves. My work focuses on quantifying their ability to reduce excess nutrients—particularly nitrogen and phosphorus—and assigning a monetary value to these benefits within the UK. This ties into Seafish’s broader mission of supporting the UK seafood industry, including the shellfish sector. We collaborate closely with the Agri-Food and Biosciences Institute (AFBI) in Belfast, with valuable input from organisations like NOAA in the US and Longline Environment in the UK.

And why do we look at this? Nutrients like nitrogen and phosphorus are fundamental building blocks of life on this planet. They’re great—until there’s too much of them. Excess nutrients in water bodies lead to eutrophication, where algae get a little too enthusiastic about their all-you-can-eat buffet. This results in rapid algal growth, leading to blooms that can suffocate marine ecosystems.

Enter bivalves. Mussels, oysters, and clams filter water, drawing in tiny food particles like phytoplankton and algae. In doing so, they help keep the water clearer and healthier, reducing the risk of algal blooms. But their contributions don’t stop at filtration. Bivalves also create habitats. Over time, their shells accumulate on the seafloor, forming reefs that provide shelter for all sorts of marine life—fish, crabs, sea snails, you name it. Bivalve areas act as breeding grounds and nurseries, supporting biodiversity in coastal waters and even helping stabilise shorelines by reducing wave energy and trapping sediments. The structures used in bivalve farming provide surfaces for other species to attach and thrive, enhancing the overall health of marine ecosystems. This is a prime example of how sustainable seafood production and conservation efforts can go hand in hand.

Beyond their ecological role, bivalves are also a crucial part of the UK’s aquaculture sector, supporting both marine health and local economies. In 2019, the UK produced approximately 16,000 tonnes of bivalves, valued at nearly £22 million. The cultivation methods vary depending on the species and location, with techniques including suspended cultivation in sheltered bays and estuaries, as well as intertidal farming at the bottom or using trestles. In some areas like Lyme Bay, innovative approaches such as offshore mussel farms are being explored, taking advantage of deeper waters and stronger currents to produce high-quality shellfish. Meanwhile, hatchery advancements are improving seed supply, helping farmers grow more resilient and productive stocks. The diversity in cultivation methods reflects the adaptability of the sector, ensuring that bivalve aquaculture can thrive in different coastal environments while supporting marine biodiversity and local economies.

Despite recent declines in production, the UK shellfish industry continues to provide enormous environmental benefits. Our work estimated that the UK shellfish industry removed between 126 to 286 tonnes of nitrogen in 2019 alone. Mussels and oysters are particularly effective in this regard due to their higher nitrogen content and substantial production. This natural filtration process supports marine ecosystems and could be worth between £7 to £16 million annually compared to traditional wastewater treatment methods. This is what excites me most—not only do bivalves provide a valuable, nutritious food source, but they also actively improve our marine environments in ways we’re only beginning to quantify. Integrating ecosystem services into seafood production is crucial for supporting both environmental health and economic sustainability and increasing future bivalve production will only lead to even better nitrogen removal.

Bivalve aquaculture isn’t just a green solution for the planet—it’s an opportunity for an evolving, future-facing industry that can drive positive environmental and economic change. While we can’t ignore the financial side—after all, a £22 million industry is hard to overlook— it is about working with nature, not against it, and embracing sustainable solutions and enhancing natural processes in our seas. Globally, there is growing support for including bivalves in nutrient management plans, with ongoing research highlighting their environmental and economic benefits. With larger shellfish industries in Europe, like those in Spain and France, struggling against the warming effects of climate change, the UK’s geography offers an extensive coastline and a uniquely resilient environment for sustainable shellfish aquaculture to expand. Increasing future bivalve production will only lead to even better nitrogen removal and more resilient coastal ecosystems. And every little effort counts. No single solution will fix everything, but optimising nature-based solutions like this can make a real difference in improving our future.

With growing research funding, like the new grants from Fishmongers Company, and advances in aquaculture practices, we’re not just looking at the future of shellfish—we’re looking at a model for sustainable resource use that could shape the future of global marine management. The world is quite literally our oyster when it comes to exploring the potential of these humble heroes of our seas. And while this progress is exciting, there’s still more to do. Expanding bivalve aquaculture will only deepen these benefits, improving coastal resilience and bolstering local economies. This also means there are plenty of opportunities for young professionals to anchor themselves in the shellfish sector and explore its potential.

When I first entered the shellfish industry, I was pretty clueless. I didn’t know much about the world of mussels, oysters, and clams. There was so much to learn—from the regulations and the different players in the sector to figuring out how all the rules and bodies fit together. I didn’t know where to start or how it all connected. But what made it possible was the community. What struck me was how quickly I felt welcomed. It was like stepping into a new world, where people were genuinely eager to help me find my footing. And that’s what’s kept me hooked—there’s always something more to learn, and it’s always in great company.

You've read all of that, and hopefully, by now, you’re convinced that bivalves are great—morale-boosting food, with the potential to be the ‘it girl’ of the seafood sector. They come with fantastic ecosystem benefits, a solid financial case, and an incredible community of growers, researchers, and supporters in the regulatory bodies. So, what’s holding them back? A detailed analysis would be a bit much for this blog (and I know I’ve rambled on enough already), but one major challenge the industry faces is attracting young people. It’s certainly a wider issue in aquaculture, but shellfish aquaculture feels even more niche. Yet niche doesn’t mean small — it means untapped, underestimated, and absolutely worth the dive. So, if you're curious, why not start exploring? A quick online dive could be your first step into something new and exciting.

Caption: ECRs at the ASSG conference in Oban, 2025. All researching into different aspects of the bivalve sector.

If this piece has sparked your interest, feel free to reach out to me or other shellfish fans in YAS. You can connect with us on YAS Aqua Hub or message YAS to help facilitate a conversation. It’s a fascinating sector to consider, whether you’re deciding on a career after your degree or just curious about where aquaculture might take you. And if you want to learn more about the water quality ecosystem services of bivalves, check out this blog summarising the work: https://www.seafish.org/about-us/news-blogs/the-environmental-and-economic-benefits-of-bivalve-aquaculture-in-the-uk/