The Rugulopteryx okamurae invasive species is no longer confined to the Strait of Gibraltar. Seaweed strandings have spread along the Cádiz coastline as far as Rota, and signs of its presence are now being detected on the seabed off the Northwest Coast. Coastal municipalities, convened by the Cádiz Provincial Council, have once again highlighted the unstoppable spread of this invasive species and the challenges it poses to Spanish coastlines, which this year has seen record numbers in several locations.
The meeting of the Permanent Working Group on Invasive Algae served to review the season and to agree on a formal funding request to the Ministry for Ecological Transition and the Demographic Challenge and the Regional Ministry of Sustainability and Environment of the Andalusian Government. The idea is for the administrations with the necessary powers and greater resources to assume part of the expenses that currently fall on the municipalities.
Expansion and tons removed
The data provided by the local councils reveals a staggering increase . Rota leads the way in removals with 10.000 tons, far surpassing Tarifa with 3.000; Cádiz, 1.379; La LÃnea de la Concepción, 550; Algeciras, 300; Chiclana, 250; and Conil, 40. The geographical shift is also striking: in 2019, the problems were concentrated in Algeciras, La LÃnea, and Tarifa, while now the invasion of the Asian seaweed is jeopardizing the entire Spanish coastline, reaching the Rota waterfront and beginning to colonize the seabed off the Northwest Coast.
In La LÃnea, Poniente beach has collected over 550 tons of seaweed so far this year, a figure that surpasses the volume of each of the last three years and makes this the third highest year since records began, coinciding with the first appearances of the algae in 2014. The Councilor for Beaches, Rafael León, and the Vice President of the Provincial Council and head of Ecological Transition, Javier Vidal, participated in a meeting that addressed an expansion that has already reached Conil.
A bill that keeps growing
Current regulations assign the responsibility for removing seaweed deposited on their beaches to local councils. This necessitates increased services, additional hiring, and the rental of machinery, especially during peak tourist season. The Provincial Council reports that it has granted €1,8 million in subsidies to municipalities over the past five years, although it acknowledges that it lacks direct jurisdiction in this area.
Javier Vidal summarized the next step: listening to the municipalities to understand how they coped with the summer, but also formally requesting the mobilization of financial resources from higher levels of government. The request is addressed to the Ministry and the Regional Government of Andalusia, and follows up on a proposal approved by the Provincial Council in July. Furthermore, the Provincial Council of Cádiz will be asked to join the national working group on Rugulopteryx okamurae to convey the needs of the Cádiz coastline.
Impact on the ecosystem and on the corrals
The problem doesn't end when the algae reaches land. In sensitive areas like the Corrales de Rota fish weir, the algae blooms have clogged walls and grates, hindering water renewal and depriving wildlife of oxygen. The weir workers have described instances of mollusks, crustaceans, and small invertebrates suffocating under the biomass, as well as damage to walls and grates caused by the force of the water when the channels became clogged.
Andrés Barba, a local farmer and science communicator, explains that cleaning the area is more complicated than it seems: the sand beneath the seaweed cannot be removed , and once it's cleaned, the tide can refill the area within a few days. In the long term, he's confident that the ecosystem itself will find a balance, with predators like sea urchins beginning to feed on this species. Meanwhile, coexisting with the seaweed and its periodic removal remain essential for preserving the natural monument.
Possible uses and monitoring in Galicia
The provincial council and city councils have also agreed to study technically and economically viable alternatives to utilize the harvested seaweed within circular economy strategies. The dual objective is to find a use for thousands of tons of organic matter and manufacture feed de peces aquaculture to offset, at least in part, the increasing cost of keeping beaches free of seaweed wrack.
In Galicia, the Algadest project has confirmed that detecting Rugulopteryx okamurae using environmental DNA is effective. The University of Santiago and the Galician Ministry of the Sea have defined a molecular marker to differentiate it from closely related species and are already applying the technique at 90 locations along the Galician coast, 20 of them in the Arousa estuary. Direct observations indicate that the population in O Grove continues to grow, while no settlements have been found further inland.
Researcher Pilar DÃaz Tapia points out that the technique is particularly useful with water samples and that its effective range is around 200 to 300 meters . In San Amaro (A Coruña) and Monteferro (Nigrán), the established populations are a cause for concern because they cover the seabed, although in Galicia, for now, no whaling incidents comparable to those in the southern Iberian Peninsula have been observed. The aim is to have a rapid and preventative mapping system that allows for anticipating the spread of the species.
Claims and next steps
The Working Group is maintaining its pressure to ensure the problem doesn't remain confined to the local level. The municipalities believe the scale of the problem exceeds their budgetary capabilities and that the national and regional governments must become more involved with additional resources. The request also seeks to give Cádiz a voice in the national group created to address the fight against the invasive algae Rugulopteryx okamurae.
The situation in Tarifa clearly illustrates the effort: around 3.000 tons removed this year make it the second municipality in the province in terms of volume, second only to Rota. The length of its coastline and the recurring nature of the seaweed influxes make it a constant problem for municipal services, which must balance cleanup efforts with tourism and fishing activities.
The impact has also reached the Congress of Deputies, where the Vox party has asked the government for concrete measures. Los Corrales de Rota holds the Q for Tourism Quality and the S for Sustainable Tourism certifications, which are reviewed through periodic audits and depend, in part, on the environment being maintained in good condition.
The spread of Rugulopteryx okamurae continues to dominate the agenda along the Cádiz coastline, with Rota and Tarifa leading the way in removals and a cost that the municipalities cannot bear alone. Requests for funding, the search for uses for the biomass, and monitoring in other areas such as Galicia outline a medium-term strategy for a problem that, far from disappearing, has become entrenched on the Spanish coast.
