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A new report highlights the barriers and optimum conditions for kelp recovery and restoration in UK waters. The report concludes that reducing impacts such as eutrophication, pollution, disturbance, and sedimentation from dredging and trawling is the priority in the short term to optimise natural kelp recovery. The findings suggest this should be done before any extensive investment in assisted restoration.
Kelp forests are considered among the most biodiverse ecosystems on Earth – each individual kelp hosting as many as 80,000 individual organisms. Unfortunately, they are threatened by global and local scale pressures, including climate change. Rising sea temperatures and increases in the frequency, intensity, and duration of extreme weather events are having a significant impact. Human activities such as pollution, trawling, increased sediment, and invasive species also result in the degradation and loss of kelp forests around the world.
In the UK, kelp beds are estimated to occur along ~60% of the coastline. Recent assessments indicate that kelp forests are relatively stable domestically, with little evidence of widespread losses or local extinctions. The exception is off the coast of West Sussex, where once extensive kelp forests declined significantly since the late 1980s. Now, less than 5% of the historic area remains. The Great Storm of 1987, an increase in bottom towed fishing and reductions in coastal water quality contributed to this decline.
To support recovery of kelp and the wider marine ecosystem, the Sussex Inshore Fisheries and Conservation Authority (IFCA) established the Nearshore Trawling Byelaw in 2021. This landmark fisheries management byelaw banned bottom trawling across more than 300km² of Sussex seabed, allowing essential fish habitats, including kelp forests, the chance to recover.
Four years on there are encouraging signs of ecosystem recovery with increased abundance of fish species, such as black seabream and increased extent of blue mussel beds. Kelp bed resettlement will take several years, but there are early signs that the remnant kelp beds are starting to spread.
Blue Marine Foundation, scientists and partners in the Sussex Kelp Recovery Project are concerned that the trawling byelaw alone may not be enough. Reducing other pressures is also going to be vital to optimise conditions for natural recovery.
Sam Fanshawe, Senior UK Projects Manager from Blue Marine Foundation, said: “The landmark Sussex IFCA Nearshore Trawling Byelaw was the first vital action to remove the main cause of disturbance to the seabed and create the conditions needed for kelp to resettle and grow. Sadly, other impacts such as increased levels of sediment, nutrients and pollution could impede natural recovery of kelp habitats and the wider marine ecosystem. The report on UK Kelp Recovery: Barriers and Optimum Conditions aims to draw together our knowledge of the key factors needed to allow kelp growth and the return of the once abundant kelp beds in Sussex and avoid declines in other regions.”
In Sussex, sedimentation (from cliff erosion, terrestrial run-off, and nearshore dredging and disposal) poses one of the most significant threats to kelp recovery. High levels of sediment can prevent kelp settlement, bury kelp spores, and reduce light in the water column necessary for kelp growth. Extreme sea temperature change may also impede kelp recovery. Collectively these factors, along with other stressors such as nutrient and pollution inputs, could impact the return of kelp along the Sussex coast. Species that were historically present could also be replaced by those more tolerant to the changing environment.
The report authors* set out to share what we know about historical kelp presence in Sussex, the optimal environmental conditions for natural kelp recovery, limiting factors to natural recovery and active restoration, and the monitoring and research requirements to track the recovery of kelp habitats.
Professor Pippa Moore, of the University of Newcastle, one of the authors of the report, said:
“Having a sound understanding of the conditions that encourage or hinder kelp recovery when it is disturbed is vital before making informed management decisions on whether passive or active approaches to kelp recovery are required. This report provides the context for UK waters”.
The report, ‘UK Kelp Recovery: Barriers and Optimum Conditions’ is published today by Blue Marine Foundation ahead of a UK Kelp Summit on 2 April, organised by Sussex Kelp Recovery Project partners.
The Kelp Summit is the UK’s first national kelp ecology conference bringing together national researchers, conservationists and policy makers to share knowledge and explore the next steps in rewilding our seas.
Authors* – Dr Hannah Earp and Professor Pippa Moore (University of Newcastle), Sam Fanshawe (Blue Marine Foundation), Dr Chris Yesson (Zoological Society of London) and Dr George Balchin (Sussex Inshore Fisheries and Conservation Authority).
Read the full report here.
Read more on Blue Marine’s work to support kelp recovery here.
