Across inland waters in Spain and Portugal, inventories show a rise in alien and invasive species over recent years. In 2021 the count stood around 300, growing to 306 in 2022 and reaching 326 within the project context. The figures cover animals, plants, algae, and fungi that are not native to Iberian habitats and pose a threat to local biodiversity.
Alien species threaten native wildlife and plant life by competing for space and resources. Their spread often aligns with declines in indigenous populations, potentially pushing some species toward endangerment or extinction if not addressed.
The study behind these findings involved 65 experts from nearly thirty Spanish and Portuguese institutions and was published in NeoBiota, a leading journal in biological invasions.
The most notable invader in Spain is the zebra mussel, which has caused significant ecological disruption.
The explanation for the latest inventory comes from Francisco Oliva, coordinator of Life Invasaqua and a professor at the University of Murcia. He described the invasive alien species present in Iberian waters as a key reference for evaluating how state and European regulations are implemented in practice.
A total of 326 exotic species were identified across rivers, reservoirs, lagoons, and estuaries. Of these, 215 are established in the wild, 96 are in an uncertain state of establishment, and 15 are cryptogenic taxa whose biogeographic history makes a clear native or exotic classification difficult.
Crabs, molluscs and fish
Among the most abundant groups are arthropods such as the American red crab and blue crab, mollusks like zebra mussels and Asian clams, and vertebrates notably fish including catfish, carp, and gambusia. Oliva emphasized that most introductions have occurred recently, underscoring the urgency for swift prevention and response to these exotics.
American crabs and other invasive species have become more prevalent in European waters, highlighting the growing need for coordinated monitoring and management strategies across regions.
Only about a quarter of the listed species appear in national catalogs of invasive exotic species for Spain and Portugal. The authors stress that inventories help update national catalogs and advocate for transnational strategies to address invasions across neighboring EU countries effectively.
Life Invasaqua has been financed with European funds, working over five years to raise public awareness about invasive alien species in freshwater and estuary systems in Spain and Portugal. The project highlights the importance of coordinated actions across parties and sectors to curb invasions.
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