Case Study 10 – Wakame

Case Study 10: Wakame

(Undaria pinnatifida)

Description

Wakame is a large species of brown seaweed native to Northeast Asia. It is recognised by the IUCN as one of the 100 world’s worst invasive species due to its significant ecological and economic impacts. While it has economic value as a nutrient-rich edible organism used in Asian cuisine, it is a highly aggressive invader. It features an annual life cycle with a growth rate that is significantly faster and more productive than many native species.

Habitat

This seaweed is currently established in most European seas and is present at the southern limits of the Danish North Sea. It requires a hard substrate to grow. A major concern is the stepping-stone effect, where offshore wind farm structures—such as turbine pillars and rock-layered scour protection—provide the necessary hard surfaces for Wakame to spread across otherwise sandy, soft-sediment areas into new regions.

Impacts

Biodiversity: Wakame rapidly outcompetes and displaces native foundation species, such as native large brown algae.
Infrastructure: It is a major fouling species that clogs marinas, blocks intake pipes for power stations, and coats the hulls of boats and harbour structures.
Economy: Infestations can foul commercial shellfish beds and cages, leading to slower growth of the shellfish and higher maintenance costs.

Prevention and control actions

The GuardIAS project is using advanced modeling and monitoring to prevent the seaweed from reaching protected Danish Natura 2000 areas.

Predictive Modeling: Researchers combine 3D hydrodynamic models of sea currents with agent-based modeling to predict how Wakame will spread under different offshore wind farm scenarios. Predictions of its spread are expected in spring 2026.
Early Detection: The project uses environmental DNA (eDNA) water samples to investigate the presence of Wakame in existing wind farms and applies the CIMPAL tool for impact assessments.
Feasibility Studies: Using a 10 Tenets approach, the team is evaluating management options such as cleaning pylons, using hydrophobic surfaces on structures, or altering scour protection to limit spread.
Citizen Science: A program has been initiated to gather local observations in coastal regions. Because the seaweed is large and easily visible if it detaches and washes up on beaches, public reporting is a vital tool for tracking its movement toward Danish waters.

Useful links

Meet the case study team

AARHUS Universitet: Peter A.U. Staehr, Helle Buur, Charlotte Clubley, Hans Jakobsen, Adam Koziol, and Christian Mohn

Case study contact: Peter A.U. Staehr, pst@ecos.au.dk

Anastasija Zaiko

“This project is not just about managing invasive species today—it’s about developing a proactive approach that anticipates future ecological challenges, ensuring robust ecosystems and sustainable marine environments for generations to come”

Sergej Olenin

“For over 35 years, since I first began studying non-indigenous species, I have dreamed of tools that could reveal the ‘Big Picture’ of the transfer, spread, and impacts of invasive aquatic species. Thanks to advances in new technologies, the GuardIAS project now offers an outstanding opportunity to make that vision a reality.”

There are 7 Work Packages (WP) focusing on different stages of invasive alien species ‘invasion’ in the GuardIAS project. Each Work Package is a distinct project area, but all are interlinked through GuardIAS as a whole.