Case Study 11 – Rugulopteryx okamurae

Case Study 11: Rugulopteryx okamurae

Description

Rugulopteryx okamurae is a brown alga native to the Northwest Pacific and is considered one of the most aggressive marine invaders currently known. It is an Invasive Alien Species (IAS) of Union Concern that has already established itself in Spain’s Alboran Sea and parts of France. The species is highly prolific; a single plant can produce up to 600 copies of itself through asexual reproduction, leading to an unstoppable and rapid advance.

Habitat

This alga thrives in marine environments, specifically growing on hard substrates such as rocks in the shallow sub-tidal zone. It has the potential to inhabit coastal areas across the Mediterranean, including Portugal, Italy, Greece, Croatia, Slovenia, Cyprus, and Malta. It is known for its ability to expand extremely fast and homogenise habitats, physically displacing vital native ecosystems like Posidonia oceanica meadows.

Impacts

Biodiversity: Rapid colonisation displaces native species and alters community structures. Because it contains chemical compounds that make it unpalatable to local herbivores, native fish cannot eat it, leaving them without food in invaded areas.
Fisheries: Floating biomass reduces capture rates for inshore fisheries by scaring away fish and clogging fishing nets, which significantly increases cleaning costs and lowers income for fishers.
Tourism and Public Health: Large, foul-smelling piles of algae frequently wash onto beaches, creating unattractive environments for tourists and impacting local economies.

Prevention and Control Actions

Because large, established populations are virtually impossible to eradicate, the GuardIAS project focuses heavily on early detection to prevent full-scale invasions.

Early Warning System: An early warning network is being implemented in Greece involving divers, NGOs, and researchers to monitor potential entry points like ports and marinas.
Innovative Sampling: The project uses “POMPOMs” (Polyamide Meshes for Ports Organismal Monitoring)—innovative zigzag mesh devices that collect biofouling communities over a one-month period for environmental DNA (eDNA) analysis.
Rapid Response: If the alga is detected, coordinated eradication efforts will be immediately initiated in collaboration with the Greek National IAS Committee and competent authorities.
Potential Resource Use: In cases where eradication is not possible, researchers are exploring ways to utilize the massive biomass for pharmaceutical and chemical purposes, such as extracting antioxidants and anti-inflammatory compounds.

Useful links

Meet the team

University of the Aegean: Panagiota Xanthopoulou, Chrysoula Gubili, and Stelios Katsanevakis

Case study contact: Panagiota Xanthopoulou, giota_xan@hotmail.com

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.