Some environmental battles are won through eradication. Others demand a different kind of wisdom—the recognition that a species has become so firmly established that the challenge is no longer elimination, but adaptation. Such is the reality confronting the Azores in its struggle against Rugulopteryx okamurae, the invasive brown seaweed that has spread rapidly through the archipelago’s coastal waters over the past six years.
According to a comprehensive multidisciplinary study commissioned by the Regional Government of the Azores and conducted by the University of the Azores, complete eradication of the invasive algae is no longer considered feasible under current conditions. Instead, researchers argue that the Region must adopt a long-term management strategy centered on continuous monitoring, early detection of new outbreaks, mitigation of ecological impacts, and the sustainable use of the growing biomass.
Presented in Horta and coordinated through the University’s Okeanos Institute of Marine Sciences, the study represents the most detailed scientific assessment yet undertaken of a species that has rapidly become one of the greatest ecological challenges facing Azorean coastal ecosystems.
Bringing together specialists from Okeanos, the Centre for Research in Biodiversity and Genetic Resources (CIBIO), the Institute for Research in Agricultural and Environmental Technologies (IITAA), and the Centre for Ecology, Evolution and Environmental Changes (cE3c), the project provides both an assessment of the algae’s ecological impact and a roadmap for future management.
The researchers’ conclusion is both sobering and pragmatic.
Rather than pursuing an increasingly unrealistic objective of complete eradication, they recommend focusing resources on surveillance systems capable of identifying new infestations before they become widespread, reducing ecological damage where possible, and exploring ways to transform the invasive species from an environmental liability into an economic resource.
Since its first detection on São Miguel in 2019, Rugulopteryx okamurae has expanded with remarkable speed throughout the islands of the Eastern and Central Groups. Evidence now suggests that it has also begun reaching the Western Group, underscoring the extraordinary capacity of the species to colonize new environments.
In many coastal areas, the algae now form dense underwater carpets extending to depths of nearly 40 meters, completely covering the seabed and displacing native macroalgae that have long supported the archipelago’s marine ecosystems.
The consequences extend far beyond the algae itself.
As native seaweed communities disappear, the biodiversity of benthic habitats declines significantly, altering ecological relationships that have evolved over centuries. The study further demonstrates that Rugulopteryx okamurae possesses an exceptional ability to adapt to Azorean environmental conditions, with particularly rapid growth during the spring months.
By summer, those extensive underwater colonies begin to fragment naturally. Detached algae accumulate along coastlines in large quantities, creating massive deposits on beaches and shorelines that present both ecological and practical challenges.
The impacts are increasingly visible not only beneath the sea but also above it.
Researchers note that the invasive algae affect recreational activities, water sports, and maritime tourism, particularly scuba diving and coastal leisure. Large accumulations of decomposing biomass reduce the aesthetic appeal of beaches and generate significant socioeconomic costs for coastal communities required to manage the growing volumes of stranded seaweed.
Yet amid these challenges, the study also identifies unexpected opportunities.
Rather than treating the algae solely as waste, researchers explored several potential applications capable of creating value from the invasive biomass. Among the most promising are the production of biochar for improving acidic soils, its potential use as a biofertilizer, and its possible inclusion in livestock feed to help reduce methane emissions from ruminants—an area of growing international interest as agriculture seeks to reduce greenhouse gas emissions.
Scientists also investigated the extraction of bioactive compounds possessing antioxidant, antibacterial, and anti-inflammatory properties, opening potential avenues for applications within the pharmaceutical, cosmetics, and biotechnology industries.
Such possibilities illustrate an increasingly important principle in environmental management: even invasive species, when responsibly managed, may contribute to scientific innovation and the circular economy.
The researchers caution, however, that such opportunities are not without complications.
In several coastal areas, particularly at Porto Pim and Porto do Alcaide on Faial Island, large deposits of algae have become contaminated with plastic debris washed ashore alongside the biomass. This contamination complicates collection efforts and may limit future industrial uses unless integrated waste-management strategies accompany any harvesting program.
The study therefore emphasizes that future utilization of the algae must incorporate careful environmental management alongside technological development.
Monitoring, meanwhile, remains the cornerstone of the proposed strategy.
Scientists have already strengthened surveillance through an innovative combination of field observations, satellite imagery, and citizen science, creating a monitoring network capable of tracking the algae’s expansion more efficiently than traditional methods alone.
This integrated approach offers considerable promise for developing early-warning systems that predict future accumulations on Azorean beaches, enabling authorities and coastal communities to respond more effectively before significant impacts occur.
Ultimately, the story of Rugulopteryx okamurae reflects one of the defining environmental realities of the twenty-first century. Global shipping, changing ocean conditions, and increasingly interconnected marine ecosystems mean that biological invasions are becoming more frequent and more difficult to reverse. For island regions such as the Azores, whose extraordinary marine biodiversity represents both a natural treasure and an economic resource, responding successfully requires not only scientific knowledge but also sustained cooperation between researchers, government agencies, maritime industries, and the public.
The University of the Azores’ study makes clear that the question is no longer whether the invasive algae can be removed entirely—it cannot. The challenge now is whether the Region can learn to contain its impacts, anticipate its spread, and perhaps even transform an ecological threat into an opportunity for innovation. In that effort, science will remain the archipelago’s most valuable ally.
Based on a story in Diário Insular-José Lourenço-director. Photos from DI.