Why restore kelp forests?

Found along almost a third of the world’s coastlines, kelp forests play a vital role in marine ecosystems by providing habitat and food for a diverse range of marine species.

The UK and Ireland represent an important area for kelps, with 7 different species, covering an area up to 20,000 km2 along the UK’s coastline. Kelp habitats support essential ecosystem services, including fisheries habitats, biogenic coastal protection, nutrient cycling, and carbon uptake and storage. 

However, kelp beds are declining across the world, with losses stemming from a variety of physical and biological factors such as climate change, decreases in water quality, coastal development, overgrazing, overharvesting, and pollution. 

Local declines of kelp forests have been reported in certain areas in the UK. Early warning signs of climate change and human activities include species range shifts, with cold-adapted kelp species declining in southern England.

Losses or shifts in the structure of kelp forests in the UK could have significant consequences for marine ecosystems and the services they provide to coastal communities. The UK lags behind international marine restoration, having only recently made limited progress towards restoring seagrass meadows, saltmarshes, oyster reefs and kelp beds.  

 

Pioneering kelp restoration trials in England

Scientists at Plymouth’s Marine Biological Association (MBA) and Newcastle University have begun trials to progress an active kelp restoration technique for four species of native kelp (Order Laminariales), using test sites in Devon and Durham. The technique works by seeding kelp spores onto small rocks and scallop shells – a seafood waste product – in efforts to regenerate the UK’s coastal kelp forests.  

The fundamental goal of the project is to develop a system for restoring degraded kelp forests using a low-cost, scalable, and practical solution, whilst bridging the gap between marine conservation and the fishing and seafood industry. 

From tanks to seabed trials

The restoration method adopted for this project is known as ‘green gravel’ and was first pioneered in Norway in 2020. To start the trials, a dedicated controlled temperature room was set up with tanks, pipework, racking, filtered seawater, UV sterilization, and specialist lighting.

This project, which is the first of its kind in the UK, uses these controlled laboratory conditions to grow native kelp species using fertile ‘sorus’ material (seed) obtained from local donor plants. To do this, sections of frond filled with spores are cut out and bought back to the lab, then disinfected with a quick dip in iodine solution. The fertile kelp material is dried and rehydrated to initiate the release of hundreds of millions of microscopic kelp spores. 

The shells and gravel needs to be cleaned and put into tanks of seawater, prior to the spores being added. Once the spores are added, the kelp seedlings grow rapidly and are visible as a brown fuzz within three to four weeks. To optimise seeding methods, tests are  comparing the success of seeding with both spores and microscopic gametophyte life stages. 

Scientists at the MBA have also recently started to assess kelp settlement density, growth rate and attachment strength on both sides of scallop shells, using flat, concave and crushed shells. Evey year, more than 30,000 tonnes of shells go to landfill in the UK, at a cost to the industry. There’s huge potential to use shells as a restoration material at scale, either whole or crushed into smaller pieces.  

Once juvenile kelp plants have grown large enough (~1cm long), normally after a period of three months or more, the substrates and kelp will be out-planted at sea by simply dropping the shells and gravel over the side of a boat where they sink, allowing the kelp to attach to the seabed where it grows to maturity. This method means there is no need for expensive, labour-intensive dive teams to install kelp onto the seabed. 

The team at the MBA and Newcastle University, in partnership with the local fishing fleet, will monitor the kelp habitats every few months for several years. Early laboratory trials results have produced promising results, however the ultimate success will likely vary due to local conditions at each site.   

The project has been working closely with the fishing communities from the North East Fishing Collective, Whitby Fishing Association and Plymouth Fishing and Seafood Association. The ambition is that the fishing fleet will support the out-planting activities on an ongoing, paid basis. 

Their progress over the next three years will inform kelp restoration methods through the Green Gravel Action Group which recently identified international challenges and solutions to marine forest restoration. The scientists and industry partners involved in this project are working together to find out how to best to adapt green gravel methods to specific locations and wave conditions in the UK. 

If scalable and effective in different scenarios, this technique could provide a sustainable use for waste shells, reducing the volume sent to landfill each year nationally, while restoring crucial ocean habitats. 

The project has been collaboratively funded by the Marine Management Organisation, Fishmongers’ Company’s Fisheries Charitable Trust, Newcastle University, Seafarers Charity, Marshall Wace, Devon Environment Foundation, and the Dixon Foundation. 

Devon Environment Foundation’s funding was generously provided by Graphite Capital and dryrobe®.

Discover more on the MBA website here.

Image credits: Main image copyright 2024 Marine Biological Association. 

Smaller images courtesy of The Kelp Conservation Initiative CIC.