‘Sea urchins are bizarre animals – and they really are a bit of a mystery,’ says Johan Johansen, one of the lead researchers at Ocean Green partner NIBIO, who is working on quite literally unravelling the secrets of these spiky creatures.

Talking about his first interactions with urchins as a child, he recalls finding them picked clean by seagulls in the summers. ‘If you were very lucky, you could find one with a small hole, and then you could actually keep it. That was a thing of beauty.’

Fast forward to today and Johansen and the NIBIO team have been working on finding ways to use the urchins that will be harvested though the Ocean Green project, which has the ultimate goal of reducing urchin density to levels compatible with the return of kelp to northern Norwegian waters.

Native and needed – but too many

While the urchins are a native – and needed – species, the over fishing of urchin predators in recent decades has resulted in an overpopulation of the creates, with the result that estimates put kelp forest loss in the region as high as 80% over 50 years.

So, as Ocean Green develops its system to remove large quantities of urchins from so-called urchin barrens, NIBIO is working out what to do with them – including exploring their use as a biostimulant in food production.
Johansen says the urchins have proved surprising from the get go.

‘They have some really cool stuff going on, that we still don’t fully understand,’ he says. ‘At the same time, much of what we thought would work well based on previous experiences proved to be less effective than expected,’ he continues. ‘That meant retracing some steps and, in some areas, starting from fresh.’
The sheer strength, responsiveness and adaptability of Norway’s green sea urchins were all surprising to Johansen.

‘Urchins use hydrostatic pressure to sort of push out an arm and attach to something,’ he explains. ‘I thought that mechanism would be ruined if the shell broke, but that is not the case. They seem to be programmed to go around and nibble at whatever they come across – which might well include a neighbour. It doesn’t matter, they just nibble away. So you get urchins with a hole in the shell. These damaged urchins can climb the walls of the aquarium just as well as any other. That was a surprise to me.’

Then there is their strength – and the fact they make choices around how well they need to be attached. ‘We learned that they can adapt their attachment. If you are poking around at them, they’ll assume you’re a predator and do everything they can to grip on – it’s as if they have glued themselves to the substrate.’

In their study environment, where urchins have access to the glass aquariums that Johansen describes as ‘a perfect surface for sucking onto,’ he says their power ‘would be equivalent of lifting several kilos of weight’.

Hens and fish

As well as studying how urchins work from the outside – in order to be better removed from the substrate – the NIBIO team is looking at what can be made from a harvested urchin with the goal of establishing a zero-waste system.

‘As well as exploring biostimulants derived from urchins, our immediate thoughts went to egg-laying hens, because acquiring enough calcium to lay all the eggs that they’re producing is a challenge,’ says Johansen. ‘We know that egg-laying hens have a problem with fragile bones that become further depleted the more they lay. We think that feed using calcium-rich urchin shells could make a difference here.’

He also points to potential in aquaculture – already a huge industry in Norway and another area where new approaches to feed are urgently needed. Research has pointed to feed production accounting for as much as 57% of total greenhouse gas emissions in aquaculture. Using urchins that already need to be harvested to make way for the return of kelp could also help bring in more nutrients into the value chain.

‘I’ve done experiments demonstrating that the micronutrients – the minerals that are supplied in fish feed – are often more efficient when they come from an organic component. I would expect that to also be the case for minerals from sea urchins.’

And still, Johansen talks of yet more mystery and magic in the urchin world.
‘We reached out to another group – not part of this project – to tap into their knowledge. They have a camera to record fluorescence from marine organisms and saw that one sea urchin started emitting this light. After it dimmed, the next one started.

‘We don’t know what that is but it is another example of the mystery of these creatures. You uncover something and it leads you to the next question – they are so interesting and it is very easy to be tempted to just keep on that path of discovery.’

Protect what returns

However interesting – and beautiful – Johansen finds northern Norway’s sea urchins, this is still all about kelp restoration. To make that goal sustainable, he stresses how important it is protect the areas where restoration is happening.

‘When you reach a tipping point, the ocean is less forgiving than if you went out and cut down a forest. These kelp forests are not as resilient, so we need to make sure that we close off these areas. We cannot allow these areas to be fished,’ he says. ‘We need to make sure that we have the top predators there to keep that balance.’