They find in Spain an invasive algae from the Caribbean


The Catalan Water Agency (ACA) has detected for the first time in Catalonia and on the Spanish coasts a new invasive algae that is difficult to eradicate in Punta Falconera, in the Cap de Creus nature reserve, in Roses (Girona) and also in Es Gat, in Cap Norfeu, which belongs to the marine reserve of Cap de Creus. It is Chrysonephos lewisii, a pelagophyceae, which is a very rare class of algae native to the western Atlantic and northern Caribbean. In Europe, it had only been detected in Italy and on the island of Corsica.

Monitoring work on the arrival of invasive species on the seabed off the Catalan coast, carried out by experts from the Catalan Water Agency in collaboration with the Center for Advanced Studies in Blanes (CEAB – CSIC), have made it possible to find this invasive species. More specifically, it was detected during an underwater survey carried out in the first week of September.

It was found between 3 and 30 meters deep, while it was abundant at 20 meters and covered 50% of the seabed surveyed in the Marine Reserve. The CEAB-CSIC researcher in charge of the invasive species control team on the Catalan coast within the ACA-CEAB-CSIC collaborative project, Enric Ballesteros, says that “it is an opportunistic, fast-growing species that will predictably reduce its cover in the coming weeks as autumn sets in”.


invasive algae

Experts believe that this year’s bloom may have been favored by the unusual high temperatures this summer, such as in 2017, when the Biology Immersion Club detected other algae from this family in Palamós (Girona). According to Ballesteros, however, “We cannot guarantee that this species is here to stay, even if it is an extremely difficult algae to eradicate”. Thus, he warns that “any action in this direction would only increase its dispersion because the filaments are extraordinarily fragile”.

This algae, which can only be identified under a microscope, forms very fine filaments – like a cottony golden spider’s web – which live attached to other algae. These break up and are carried away by currents, accumulating in structurally very important organisms such as the red gorgonian (Paramuricea clavata). The Gorgonian is a cnidarian typical of coralligenous underwater landscapes, very important for ecosystems, the equivalent of trees in terrestrial ecosystems.

A serious problem, according to experts, is the bleaching process (whitening in English), which occurs when these filamentous algae massively cover benthic life (that which lives on the seabed), such as hard and soft corals (especially gorgonians, sponges, tunicates).

“By covering them, both the coral polyps and the gorgonians, it prevents them from having access to food, nutrients and oxygenation, so if the situation persists, they can starve to death”, says Conchita Rodríguez, researcher at the Department of Environmental Sciences at the University of Girona. The coral first loses its reddish color, whitens and may eventually die.


The ACA has been carrying out actions for years following the entry of invasive species on the seabed of Catalonia and in continental waters, particularly favored by maritime transport. Measures have been taken such as monitoring and control programs with the support of specialists to identify introduced benthic species and periodically assess the rate of biopollution by invasive species in coastal water bodies.

This year it has awarded a new contract to CEAB-CSIC for three years with which, among other things, invasive species will be located and identified in at least 74 areas of the Catalan coast. Monitoring programs monitor the colonization and evolution of invasive species at specific points along the coast. Some of the most recent are the Caulerpa cylindracea That is Womensleyella setacea.


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