What is growing in the North Sea?

AWI presents the first app for identifying seaweeds on the German North Sea
[03. May 2023] 

A new app is capable of identifying, visualising and describing macroalgae present in the western and eastern Wadden Sea, and around the island Helgoland. The app, called SeaKey, currently provides details for the identification of 68 brown algae species; green and red algae will follow. Developed by researchers of the Alfred Wegener Institute and external cooperation partners, it offers scientific experts and government authorities, students and interested non-experts a straightforward way to measure algae, thanks to its innovative matrix concept.

Wherever they grow, macroalgae form the basis of coastal food webs and offer a habitat for various types of marine fauna. Under the water, this plant-like group of algae can form three-dimensional “forests” that rival tropical rainforests in their complexity. Populating the rocky coasts of all oceans, from the Tropics to the polar regions, more than 10,000 species of macroalgae have been identified. Thanks to their high productivity, they fix carbon dioxide (CO2), removing the greenhouse gas from the atmosphere. Further, their functional diversity makes marine macroalgae important “indicator species”. On the basis of their stocks and drawing on European guidelines (WRRL, MSRL, FFH), the responsible state authorities assess the ecological status of coastal waters at regular intervals.

Until recently, there was no uniform, comprehensive and up-to-date guide that combined and condensed the various international identification keys for algae with a regional focus. SeaKey bridges that gap: The app is an algae key that brings the taxonomic identification of macroalgae in Germany up to speed, while gathering and harmonising information that was previously only available from a scattered mix of sources.

The browser-based app makes a valuable contribution, facilitating interested parties’ access to the world of algae and helping maintain the required level of expertise concerning the preservation of marine biodiversity. Currently, there are few experts in Germany who are capable of identifying any algae species beyond the 20 largest and most common types. But more than 300 species of brown, red and green macroalgae can be found in the biodiversity hotspot of the German North Sea – the island Helgoland – alone. This lack of expertise is partly because identifying marine macroalgae is often difficult, and because knowing and teaching about their biodiversity has largely ceased to be a priority for universities and research institutes.

The concept

“We guide users through tell-tale morphological characteristics, all the way to identifying species,” explains Dr Inka Bartsch from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Together with her colleagues, the biologist and algae expert developed SeaKey. “We focus less on biological classification, with its orders, families and genera, since even related species can look very different,” says Bartsch. Classical, dichotomous keys only offer two alternatives for each characteristic, before progressing to the next characteristic. According to Bartsch: “When you find a mistake, trying to go back a step in the classification process is difficult and often discouraging. Moreover, dichotomous keys don’t offer a comparative overview of the characteristics of similar species. That’s why we developed a matrix concept with an innovative approach that offers variable access options. Accordingly, users can start the classification at one of several levels, depending on which characteristics they want to focus on. This allows not only experts from the scientific community and government authorities, but also students and interested non-experts to successfully identify unfamiliar algae.” To promote the app’s use outside Germany and among international students, all information is presented in English.


The key is available as three product variants:

  • Digital key at the website seaweeds.awi.de/
  • SeaKey app: at the app store
  • Printable PDF offering a comprehensive overview for offline use, downloadable at seaweeds.awi.de/

In addition to the identification key itself, there is further information on the methods used, references, a glossary of terminology, and an overview of the brown algae species covered by the app, together with equivalent terms frequently found in German literature on the topic.

Technical development:

The contents of the matrix key were converted into a web-based key. The web key was implemented with the help of Local Cosmos, a browser-based software package for creating scientific apps and websites that can contain identification keys, species profiles, glossaries and other components; and was made available by and further developed with the company SiSol Systems (https://www.sisol-systems.com/).


Inka Bartsch (project lead, text and identification key developer), Tosia Schmithüsen (project coordinator, implementation, text co-developer), Ralph Kuhlenkamp (text and identification key co-developer).
Web app and design: Thomas Uher, Judith Boelke (SiSol Systems)

Financial backing:

The project received financial support from the Helmholtz Association’s Earth System Knowledge Platform (ESKP) and the Federal State of Schleswig-Holstein’s Ministry of the Environment (LfU) in Flintbek.



Dr. Inka Bartsch
+49(471)4831 1404


Dr. Folke Mehrtens
+49(471)4831 2007 


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The Institute

The Alfred Wegener Institute pursues research in the polar regions and the oceans of mid and high latitudes. As one of the 18 centres of the Helmholtz Association it coordinates polar research in Germany and provides ships like the research icebreaker Polarstern and stations for the international scientific community.

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