Since 1992, a team from the Centre for Advanced Studies of Blanes (CEAB-CSIC) has continuously monitored invasive species in the marine environment along the entire Catalan coastline. This work is commissioned by the Catalan Water Agency (ACA), of the Government of Catalonia. In 2025, efforts are being intensified regarding one species in particular: the Asian alga Rugulopteryx okamurae.
Through various public tender contracts, the ACA has awarded CEAB-CSIC the task of monitoring and controlling exotic marine species with invasive potential, under its Monitoring Programme in place along the Catalan coast since 1992. The monitoring takes place in shallow marine ecosystems across the region. The CEAB team conducts weekly fieldwork (with dives to record the degree of establishment and development of problematic species), analyzes seabed samples sent by other bodies, and verifies information shared through platforms like citizen science networks.
Currently, the focus is especially on the Asian alga Rugulopteryx okamurae, first detected in Catalonia in 2024 at specific locations along the Girona and Barcelona coasts—particularly in and near port areas.
Mariona de Torres, head of the ACA’s Coastal Waters Unit, explains: “What is happening in other parts of Spain, with large proliferations causing serious environmental and socioeconomic impacts, makes it necessary to closely monitor this alga, even though it is only present in small amounts in Catalonia. Last summer, the ACA already decided to intensify controls where it had been found, to characterize colonized areas (measuring occupied area, density, and distribution limits), and to study its characteristics and behavior to gain scientific knowledge. We’ve also tasked CEAB with analyzing potential new sample occurrences (a taxonomic analysis, since it can be confused with native species). All this information is regularly reported to the Directorate-General for Environmental Policies and Natural Environment, and to the Ministry for Ecological Transition and Demographic Challenge (through the Working Group on Invasive Species of the Generalitat’s Biodiversity Subdirectorate), to help decision-making and implementation of control actions where necessary and feasible.”
One of the CEAB-CSIC researchers monitoring the alga, Maria Garcia, states: “Every week we dive at different coastal points where we know it is established. So far, we’ve observed a slight measured increase in abundance compared to last summer, but in the same locations, with no new areas colonized. Only a few exceptions exist, where new nearby zones have been observed.” She adds, “Having as much scientific knowledge as possible about the alga and its behavior is crucial, as is its ongoing monitoring. Experts agree that any actions to stop its spread should be taken while the invasion is still limited, and must be excellently designed and implemented to avoid worsening the problem.”
The also CEAB-CSIC’s researcher, Andrea Hierro, reminds us: “Rugulopteryx okamurae spreads easily and attempting to remove it can actually help it spread, as it releases fragments that remain alive in the water column. These fragments—like a kind of soup—can be carried by currents or boats to other areas where, if conditions are favorable, the alga can settle and proliferate.”
Rugulopteryx okamurae has shown tolerance to a wide range of temperatures, and can thrive with just hard substrates, sufficient light, and relatively stable salinity, allowing it to establish itself in diverse environments far from its native Asian coasts. The lack of predators, its asexual reproduction, and human impacts (like maritime traffic and ecosystem’s alteration, making them less resilient), support its proliferation. Among the potential vectors of introduction, maritime traffic stands out, as it can transport the alga via ballast water or attached to ship surfaces.
Citizen Engagement Against the “Rugulo”
Citizen collaboration is key in monitoring Rugulopteryx okamurae. Information provided by participants in citizen science platforms like Observadores del Mar (recently honored with a special mention in the 2025 EU Prize for Citizen Science) complements the data collected by scientists and authorities. Divers and other sea-goers upload photos—among other observations—of potential invasive algal sightings, which are then verified by researchers. This effort greatly increases eyes on marine ecosystems while raising public awareness about the need to preserve them.
Citizen involvement is also vital for preventing the alga’s spread. In addition to the monitoring and studies carried out by authorities and research centers, there are several individual actions that can help prevent its distribution—such as avoiding fishing gear with embedded algae remains (It is recommended to disinfect them with vinegar to remove any algae residue), take care of diving equipment before using it in other locations, and inspecting and cleaning recreational boats.