The Urchin Density Challenge has begun!

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.

How many sea urchins will you count inside the frame?

Rissa Citizen Science is restoring kelp forests in Northern Norway with volunteers on three sites: two in Tromsø (Sørsjetéen and Telegrafbukta) and one in Øksfjord.

Until now, it was possible for anyone to participate in this effort by joining the monthly events. Volunteers could contribute from land or in the sea. But this is changing!

Volunteers joining some of the monthly kelp events in Telegrafbukta in summer 2025.

From photos to citizen science

At each event, one of our snorkelers takes around thirty photos of a 50×50 cm frame placed randomly on the seabed, both inside and outside the restoration area. These images help us track changes in sea urchin density and biodiversity over time. And this is where you come in! All you need to do is count the sea urchins you can spot inside the frame.

One of Rissa's volunteers with the frame in Telegrafbukta (photo: Ann Cools)

The first step is to download the Rissa's mobile app from Google Play or the Apple Store. Open the app, select the Urchin Density Challenge, and start counting urchins! You can also look at the photos on Rissa Citizen Science's website if you want to see larger images.

Screenshots of the Rissa Citizen Science mobile app.

The Urchin Density Challenge app was developed by Philip Redecker, who is also the brilliant architect of the Kittiwalkers' app, used by volunteers to monitor the endangered kittiwake in Tromsø. The Urchin Density Challenge is also forming the foundation of an exciting collaboration with the University of Tromsø. In the coming months, a Master’s student will use the data collected by citizen scientists to evaluate the data's reliability and study how biodiversity and biomass are changing at the Telegrafbukta kelp forest restoration site.

Install the app & start counting urchins!

And feel free to reach out if you have questions :)

That's what an urchin barren looks like! (photo: Clément Brun)

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The Urchin Density Challenge is part of the Ocean Green project, part-funded through Norway’s Green Platform, endorsed by the UN Ocean Decade and led by Ava Ocean. The project partners are NIBIO, NIVA, Hofseth Biocare and Akvaplan niva. The Ocean Green project helped fund the development of the app.