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As the seaweed farming industry in Europe expands, scientists have warned that seaweeds currently thriving in the cooler coastal waters of the north Atlantic could begin to vanish over the next 50 years.

Climate change is expected to bring higher ocean temperatures, increased storms and unpredictable salinity fluctuations because of increased rainfall. Temperature has a major influence on seaweed growth and seaweed farms can be susceptible to storm damage.

However, scientists say that sufficient investment in seaweed farming research and development could help safeguard the industry for decades to come.

published in Frontiers in Marine Science, researchers from the Scottish Association for Marine Science (SAMS), a partner of UHI, looked at five species of seaweed that are typically used in seaweed cultivation and modelled their success against projected climate change impacts.

Using temperature models, they found that the North Atlantic is expected to see losses of some cold-affiliated species such as Alaria esculenta and Laminaria digitata by 2070. 

Lead author of the report, �鶹ӰԺmarine ecologist Dr Reina Veenhof, explained that seaweed, which absorbs carbon as it grows, is often seen as a small part of the solution to mitigating climate change, but is already beginning to feel the heat.

She added: “Species such as Alaria esculenta and Laminaria digitata thrive in the relatively cool waters around the UK, northern France and the northern parts of North America but as ocean temperatures begin to rise, these seaweeds are growing outside of their ideal temperature range, resulting in poorer yield and even a loss of stock altogether.

“In the period we modelled, there seemed to be little temperature effect on seaweed grown in Scotland and similar northern latitudes, but these places will also experience more regular storms and see increased rainfall, which will challenge the conditions in which seaweed is grown.”

The paper also explored measures to better prepare the seaweed for a change in conditions and looked at the use of priming at the early gametophyte stage of seaweed cultivation. An often-used technique in agriculture, priming delivers a small dose of sub-lethal stress in early life stages (gametophytes), which can increase stress resilience later in life. This applies for all types of stress, but in the context of ocean change, thermal and salinity tolerance are particularly beneficial traits.

Dr Veenhof added: “A positive reason to grow seaweed is it is a form of aquaculture that needs no additives; it grows naturally using the nutrients in the water and sunlight. However, there is more work to be done in seaweed farming research and development to help prepare seaweed stocks for the changing environment.

“In Europe, we are well behind Asia in terms of developing these methods and the seaweed industry as a whole is a long way behind the research and development in the agriculture industry, for example.

“It will take a big effort, but I think with sufficient resources, we can safeguard a European seaweed industry for the longer term.” 

The publication Sustainable seaweed aquaculture and climate change in the North Atlantic: challenges and opportunities can be viewed here: https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2024.1483330/full