The Ocean Green project is all about the restoration of northern Norway’s kelp forests, which have been lost at a massive scale over the past half century. It is estimated that some 80% of the region’s kelp forests are gone – largely replaced by urchin barrens. The Ocean Green goal is to remove enough of these native urchins to reset the natural balance and allow kelp to return.

Around the coast of Norway, different species of kelp grow up to four meters in length, in waters where they can still get the sun in order to photosynthesise. This means that kelp take in CO2 – and release oxygen. They also play a vital role in local biodiversity as well as delivering a surprising number of other benefits.

Because of ecosystem services role that kelp plays, we have to look at its loss as a big picture issue.

Why kelp is important: multiple ecosystem services

When a kelp forest is lost, it is not just a local, physical loss. Because kelp provides such a range of ecosystem services – from nursery grounds to coastal protection, support for fisheries and more – when kelp forests disappear there is a knock-on affect across each of these ecosystem benefits.

A biodiversity haven

A healthy kelp forest is a vibrant, diverse ecosystem. NIVA – one of Ocean Green’s research partners – describes kelp forests as ‘among the most ecologically and socioeconomically important habitats on the planet.’

In Norway, the contribution of kelp can be shown in the astounding numbers of species supported by kelp forests – including commercially important fish and species on the red list. An established kelp forest supports other forms of microalgae and seaweeds, while at the invertebrate level, these marine forests boast densities of more than 100,000 individuals of snails, crustaceans, molluscs, brightly coloured marine worms and other invertebrates per square meter.

Moving up the food chain, kelp forests provide habitat, nursery grounds and food for larger species: red-list species like the Atlantic coastal cod as well as commercial species such as cod and pollock, which play an important role in Norway’s economy. These fish in turn support other, larger predators such as seals and seabirds.

Green and brown for blue carbon

Being the wonderplant that it is, kelp does so much more than provide a safe habitat for fish and other species. Kelp also serves as a carbon sink, sequestering CO2 and depositing it at the bottom of fjords and in the deep sea.

Research shows that Norwegian kelp forests bind an estimated 18 million tonnes of CO2, with around 1.8 million tonnes of CO2 exported and stored in coastal and deep-sea sediments each year. ‘If the remaining overgrazed kelp forests recovered in response to improving environmental conditions and restoration actions, a one-off binding of 12 million tonnes of CO2 within living biomass would be achieved,’ wrote NIVA in a 2021 report. ‘This would also increase the annual deposition in coastal and deep-sea sediments to around 3 million tonnes of CO2.’

Coastal defence, nutrient recycling and more

In addition to its contribution to biodiversity and carbon sequestration, kelp plays a stabilising role in its waters. This includes creating acting as a coastal defence system by creating a drag that serves to reduce wave size – which in turn protects coastal lands by reducing erosion.

Kelp also improves water quality by absorbing excess nutrients and pollutants and, though its process of photosynthesis, it increases pH levels, reducing the acidity of surrounding waters – something that further benefits marine life.

What happened to Norway’s kelp forests?

A number of factors have contributed to northern Norway’s kelp forest loss but key is overfishing, which has reduced the numbers of urchin predators like wolffish and crab. This in turn allowed native green sea urchins to spread unchecked as they overgrazed kelp. Even if the urchins are removed and kelp returned, without reestablishing their natural predators as well, the risk of overgrazing remains. NIVA says that marine protected areas or no-fishing zones across areas of restored kelp forest, coupled with quota reductions for known urchin predators, would ‘facilitate predator recovery and maintain low urchin abundances to sustain restoration efforts’. In southern Norway, climate change and warming waters appear to be bigger factors in kelp loss, according to the Norwegian Blue Forests Network.

What’s being done to bring kelp back?

Kelp loss is not a Norwegian problem but a global issue. Where the problem is caused by too many urchins – an issue itself driven by multiple factors including overfishing and climate change – urchin barrens replace kelp forests. These urchins have traditionally been removed by hand – a time and labour-intensive process that is used by volunteers who go into the water with Rissa Citizen Science, Ocean Green’s citizen science partner.

The Ocean Green plan is to develop a harvester that can remove urchins from much larger areas, much faster. Basing the technology on Ava Ocean’s gentle scallop harvester, the new urchin-removal system will speed up kelp restoration: for kelp to return, urchin density must come down from more than 30-plus per square meter to around just two urchins per square meter. Once that is achieved – and maintained – kelp can reestablish itself with remarkable efficiency.

Kelp as a restoration target

‘Despite the challenges in removing urchins en masse, kelp makes an excellent target for restoration,’ explains Dagny-Elise Anastassiou, chief impact officer at Ava Ocean and management lead for the Ocean Green project.

‘We know the cascade effect that a healthy kelp forest delivers – from serving as a nursery to multiple species to providing shelter to larger predators. We know how kelp protects the coastline and captures carbon. At the same time, we have seen firsthand – through the work of Rissa CS – just how fast kelp can reestablish itself given the chance. And how quickly fish and other species return too. And that is the ultimate goal of Ocean Green: to tip the balance back in favour of kelp – which would in turn deliver widespread benefits to the local ecosystem.’

She also points to the dual economic focus of the project as a marker of success. ‘We are not just looking to clear urchins from the seabed. We are looking to harvest them and turn them into an economically viable fishery, with our science partners working hard to uncover new, urchin-derived products. This circular-economy approach is designed to ensure the long-term sustainability of our regenerative restoration project.’