This story is a part of the GenOcean campaign — an official Ocean Decade campaign showcasing Decade Actions, collaborating organizations and ocean leaders that focus on youth and citizen science opportunities to help anyone, anywhere be the change the ocean needs.
Ocean Green, a Norway-led initiative endorsed by the Ocean Decade combining cutting-edge technology, scientific research and community engagement, has officially introduced its newest citizen-science tool: the Urchin Density Challenge, a gamified approach to analyzing transect data from underwater field photos of kelp forests and urchin beds.
Developed by Rissa Citizen Science as part of Ocean Green’s outreach and data-collection strategy, the app transforms real seabed monitoring into a simple, game-like activity. With every count of sea urchins in a small photographic frame, volunteers help scientists track the recovery of kelp forests in northern Norway – an ecosystem that has experienced one of the most extreme kelp collapses on Earth.
“We made citizen science a core part of this work because people matter,” says Dagny Elise Anastassiou, Ocean Green project manager and Chief Impact Officer at Ava Ocean. “Many ocean issues stay invisible and are easy to ignore. When people are part of the process, projects are more likely to become long term solutions. The app is easy to use and fun. Some photos show lots of urchins, others none, and suddenly colourful starfish appear. It is quite addictive.”
A Global Issue Seen Through a Local Lens
Kelp forests are disappearing on nearly every continent. In northern Norway alone, more than 80% of kelp forests have vanished, replaced by urchin barrens as grazing urchin populations surged and predators declined. Similar patterns are observed in other regions, from California, USA, and the Mediterranean to Japan and Tasmania.
When urchins overgraze, they leave behind a stark seabed with little biodiversity. These “barrens” can persist for decades. Recovery requires drastically reducing urchin numbers. Traditional approaches, often relying on divers and hand tools, cannot keep pace with the scale of loss.
“Despite the challenges in removing urchins en masse, kelp makes an excellent target for restoration,” explains Anastassiou. “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 Citizen Science – just how fast kelp can reestablish itself given the chance. And how quickly fish and other species return too. 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.”
The app is just one initiative of Ocean Green that contributes to solutions across three Ocean Decade Challenges:
2 – Protect and restore ecosystems and biodiversity
3 – Sustainably nourish the global population
4 – Develop a sustainable, resilient and equitable ocean economy
Ocean Green: A Transformational Approach to Kelp Restoration
Ocean Green is among the first initiatives to integrate large-scale urchin removal technology, scientific innovation and community involvement within a unified framework. Led by Ava Ocean and partly funded by Norway’s Green Platform, the project adapts gentle seabed harvesting technology – originally developed for shellfish – into a tool capable of efficiently collecting urchins without damaging the seafloor.
Alongside partners NIBIO, NIVA, Hofseth Biocare and Akvaplan-niva, the project explores how overabundant urchins can become the basis of new, sustainable value chains – from food products and fertilizers to enzymes, biomaterials and potential carbon credits. The goal: a zero-waste, regenerative economy built around ecosystem restoration.
“We are not just looking to clear urchins from the seabed,” says Anastassiou. “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.”
The Urchin Density Challenge: Citizen Science Made Simple
The Rissa Citizen Science app allows anyone, including students, divers, families and ocean lovers near and far from the coast, to contribute directly to kelp restoration science.
Here’s how it works:
- Download the app
- Select the Urchin Density Challenge
- Count the urchins inside a small quadrat shown in a seabed photograph
- Submit your tally
“I love seeing the different pictures and counting the urchins,” says Matilda Phillips, a 10-year-old student and ocean conservation enthusiast. “Sometimes we see other creatures in the photos too and I compete with my friends to see who can find the most urchins. It is fun but also nice, because I know I am helping to make the oceans healthier.”
The activity takes less than a minute and requires no prior training. Yet every datapoint feeds into ongoing ecological assessments and long-term recovery models.
“The Urchin Density Challenge takes citizen science to the next level, inviting people around the world to document biodiversity changes in areas where volunteers are restoring kelp forests,” says Delphin Ruché, founder and director of Rissa Citizen Science.
Upcoming Events from Ocean Green
While the app invites global participation, Ocean Green also maintains a lively local citizen-science community in Tromsø, where volunteers join monthly events to record biodiversity, take seabed photos and in some cases even dive into icy waters to manually reduce urchin numbers in restoration zones.
In January 2026, a new public exhibition on the Tromsø jetty will bring the story of kelp loss – and recovery – directly to residents and visitors. Schools across northern Norway have already participated through screenings of Stone Biter, a visually striking documentary by Ismaele Tortella, followed by discussions about marine ecology, predators and ecosystem tipping points.
“The exhibition we are creating will be an outdoor, permanent photo exhibition along the jetty in Tromsø where Ocean Green partner Rissa Citizen Science have been doing their restoration work,” says Anette Grøttland Zimowski, Chief Marketing and Communications Officer at Ava Ocean. “The photos on one side of the jetty will showcase the visual story of how volunteers have brought back a vibrant kelp forest with an abundance of marine life, whilst on the other side photos will showcase the urchin desert.”
The exhibition will open on 9 January and will be free and open to the public.
To learn more about Ocean Green and their initiatives, check out their website.
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