Hartvig Christie has been in the urchin-management business for a long time, getting to work on his first kelp-restoration project back in 1988. He has since been involved in projects that support predation or that use quicklime to kill the creatures that are decimating northern Norway’s kelp forests.

Now, Christie, a marine biologist, is part of the NIVA team that makes up part of the Ocean Green project, bringing with him decades of urchin-kelp experience. And after all these years, the goal – and the challenges – remain the same. "The major task is to remove the sea urchins and help the kelp forest coming back," says Christie. "For our ocean, it's important to develop a tool or a method for removing the urchins – so that's the first challenge right now."

The loss of Amazon rainforests under water

Research that Christie worked on, published in 2021, put the realities of kelp-forest loss – and the potential held in their restoration – into a stark light, likening the loss of some 8,400 km2 of Norwegian kelp forests to Amazon deforestation, even though the two issues are worlds apart in terms of global attention.

"Norwegian kelp forests are important carbon sinks and nutrient filters, as well as focal points for high biodiversity and abundances of commercial fish species, generating an estimated €16.7 million per km2 per year," the researchers wrote. "In comparison, boreal forests are valued at about €0.24 million per km2, which makes kelp forests 70 times more valuable than their terrestrial counterparts."

They estimate that restoring the 5,000 km2 area ‘still dominated’ by urchin barrens would provide an extra €83.6 billion per year – a value they put at three times as high as all of Norway’s terrestrial forests combined.

"There is no doubt that if Norway lost all its trees today, there would be a public outcry over their disappearance and calls for immediate restoration actions; a perception that must be adopted for kelp forest ecosystems to firmly establish their conservation and restoration as an integral part on political agendas," wrote the researchers.

Finding the perfect spot

As part of the Ocean Green project, Christie and his colleagues at NIVA are responsible for work package three: the environmental impact assessment. This involves assessing not just the effectiveness of the tools developed by Ava Ocean in removing urchins but also their potential impact on non-target species and the surrounding habitat.

NIVA is currently working to identify grounds for urchin removal and will also be involved in monitoring progress as the project moves through urchin collection and into kelp restoration – something Christie explains often happens faster than you might expect.

"We have been very surprised about the recovery of the kelp because it's so efficient – even across really long distances." Christie points to examples in both open and more sheltered water where, if you’ve removed urchins sufficiently, researchers have found not only kelp spreading from further afield on the currents but also more kelp plants growing than would be usual. "Normally, in the kelp forest, you have about 10 adult kelp plants per square meter. But [we found one restored area] that had these very tiny juveniles and there were more than 400 per square meter."

Finding solutions for a worldwide problem

The urchin-kelp dilemma is one seen across the world as overfishing and climate change lead to decreases in natural urchin predators, allowing the invertebrates to proliferate, eating their way through essential underwater forests. The result is urchin barrens where there should be kelp.

In Norway, Christie points out that the "Norwegian coastline is two and a half times the equator: lots of islands, a lot of fjords and cold water." These characteristics create their own challenges when it comes to NIVA’s job identifying areas for Ocean Green to work on. Climate change and warming seas further complicate the picture, making it harder to predict what things will look like in the future. Christie uses the brown crab as an example. "The increase in sea temperature has created a northwards extension of brown crab," he notes, with the result that, "in some parts of the southernmost areas where we had these sea-urchin barrens, urchins have been partly removed through crab prevention. Sea urchins are a cold-water species and there has also been some impact on their reproduction," he adds. These ‘no action’ areas have resulted in the return of kelp, explains Christie, though the scale of the problem in Norwegian waters means projects like Ocean Green remain essential to kelp restoration.

More questions than answers for now

These various issues – climate change, species creep, urchin management across smooth bedrock versus ‘stony bottoms’ that offer a multitude of urchin hiding places – offer up more questions than answers at the moment.

Christie talks about the scale of the issue too, noting the popularity of discussing these things in terms of football pitches. "Our calculation is more than 700,000 football fields of grazed areas," he says. Which is why a new, large-scale approach to restorative harvesting is so essential. The challenge, is to be ‘efficient’ enough for these large areas.

"This project has what you call good intentions," says Christie. "You start on the easy parts, then you can move to the more challenging tasks."

Ava Ocean, which is leading the project, is responsible for developing technology to gently but efficiently harvest urchins; NIBIO and Akvaplan-niva are fronting the research and development of urchin-derived products; Hofseth Biocare will be responsible for the marketing- efforts of those products. Wandering Owl contribute expertise to meet the social impacts elements of Ocean Green.