Spain's coasts are facing an environmental challenge of alarming proportions that is jeopardizing both marine ecosystems and the local economy. The invasive algae Rugulopteryx okamurae, native to the North Pacific, has found the perfect breeding ground in our waters to spread uncontrollably , leaving behind tons of organic waste that are hindering swimming and fishing in much of the country.
The situation in places like Marbella is especially alarming, where the number of removals of this organism has skyrocketed, far exceeding previous years' figures in just a few months. What began as a localized problem in the Strait of Gibraltar area has become a real headache for almost all the autonomous communities with a coastline, forcing administrations to coordinate containment measures in the face of its rapid spread.
A journey from Asia to the waters of the Cantabrian Sea
Since its initial detection in the Strait of Gibraltar in 2015, this species has steadily spread. Experts have proposed several theories regarding its arrival, primarily pointing to ballast water from large merchant ships or organisms attached to the hulls of vessels transiting this international waterway. Today, its presence is a reality along virtually the entire Spanish coastline, with the Balearic Islands being the sole official exception, although evidence of it has already been observed mixed with Posidonia oceanica seagrass.
The spread of the algae northward has been confirmed by environmental authorities. It is known that the algae reached the Cantabrian Sea at least by 2023, initially appearing in strategic port areas such as Bilbao and Santander . This advance demonstrates the species' remarkable adaptability, enabling it to colonize environments with varying temperatures and conditions, displacing native flora in the process.
The dead end of total eradication
The institutions have been clear on this point: with the tools and scientific knowledge we currently have, a complete eradication of the algae in the open sea is not feasible. Therefore, the national strategy focuses on minimizing the socioeconomic and environmental impacts , attempting to curb its spread through cooperation between different government bodies and the creation of specialized technical working groups.
One of the most critical periods of the year occurs between May and June, when the algae's life cycle generates an explosion of fragments that end up clogging beaches and ports. This massive proliferation unfortunately coincides with the start of the tourist season and peak fishing periods, exacerbating economic losses in the affected municipalities, which must invest large sums of money in cleaning their beaches.
Waste management and regional plans
For a municipality or company to use seaweed remains for commercial or industrial purposes, the corresponding autonomous community must have an approved Biomass Management Plan. Regions such as Andalusia, Galicia, and the city of Melilla have already met this legal requirement, allowing them to process valorization projects to convert this waste into a resource, always under strict technical and environmental supervision.
However, not all regions are progressing at the same pace with this bureaucratic process. In the case of Cantabria, despite having the necessary guidelines since mid-2024, the plan's approval has not yet been finalized, significantly limiting the area's capacity to operate. Without this document, economic development initiatives cannot be authorized, restricting actions exclusively to scientific research until the regional regulations are completed.
The current situation forces coastal communities to make a constant effort to remove thousands of tons of biomass and prevent the accumulation of algae from degrading water quality and the visitor experience. The lack of natural predators in the Mediterranean and the Atlantic, coupled with the progressive warming of the oceans, allows this Asian species to continue winning the battle for control of the seabed, leaving only long-term control and containment measures as an option.
