A horizon scan exercise for aquatic invasive alien species in Iberian inland waters

As the number of introduced species keeps increasing unabatedly, identifying and prioritising current and potential Invasive Alien Species (IAS) has become essential to manage them. Horizon Scanning (HS), defined as an exploration of potential threats, is considered a fundamental component of IAS management. By combining scientific knowledge on taxa with expert opinion, we identified the most relevant aquatic IAS in the Iberian Peninsula, i.e., those with the greatest geographic extent (or probability of introduction), severe ecological, economic and human health impacts, greatest difficulty and acceptability of management. We highlighted the 126 most relevant IAS already present in Iberian inland waters (i.e., Concern list) and 89 with a high probability of being introduced in the near future (i.e., Alert list), of which 24 and 10 IAS, respectively, were considered as a management priority after receiving the highest scores in the expert assessment (i.e., top-ranked IAS). In both lists, aquatic IAS belonging to the four thematic groups (plants, freshwater invertebrates, estuarine invertebrates, and vertebrates) were identified as having been introduced through various pathways from different regions of the world and classified according to their main functional feeding groups. Also, the latest update of the list of IAS of Union concern pursuant to Regulation (EU) No 1143/2014 includes only 12 top-ranked IAS identified for the Iberian Peninsula, while the national lists incorporate the vast majority of them. This fact underlines the great importance of taxa prioritisation exercises at biogeographical scales as a step prior to risk analyses and their inclusion in national lists. This HS provides a robust assessment and a cost-effective strategy for decision-makers and stakeholders to prioritise the use of limited resources for IAS prevention and management. Although applied at a transnational level in a European biodiversity hotspot, this approach is designed for potential application at any geographical or administrative scale, including the continental one.

Climatic Niche Shift during Azolla filiculoides Invasion and Its Potential Distribution under Future Scenarios

In order to prevent future biological invasions, it is crucial to know non-native species distributions. We evaluated the potential global distribution of Azolla filiculoides, a free-floating macrophyte native to the Americas by using species distribution models and niche equivalency tests to analyze the degree of niche overlap between the native and invaded ranges of the species. The models were projected under two future emission scenarios, three global circulation models and two time periods. Our results indicate a possible niche shift between the distribution ranges of the species, indicating that A. filiculoides can adapt to novel environmental conditions derived from climatic differences during the invasion process. Our models also show that the future potential distribution of A. filiculoides will decrease globally, although the species could colonize new vulnerable regions where it is currently absent. We highlight that species occurrence records in the invaded area are necessary to generate accurate models, which will, in turn, improve our ability to predict potential invasion risk areas.

Las plantas de la marisma del parque nacional de Doñana (España): elemento clave para la conservación de un humedal europeo paradigmático

El Parque Nacional de Doñana (SW de España), es el espacio natural protegido más emblemático del Estado Español. Incluye uno de los humedales más extensos de Europa Occidental, la marisma, que también resulta ser el mayor santuario para las aves migratorias del continente europeo. El soporte trófico y estructural de este humedal lo constituyen las comunidades vegetales que allí se desarrollan. Sin embargo, a pesar de su importancia, el nivel de conocimiento sobre los vegetales de la marisma y sus comunidades es muy escaso. Por ello, se realizó un análisis florístico de la marisma, donde se tomaron en cuenta aquellos trabajos que corresponden a citas de plantas recolectadas en la marisma y depositadas en herbarios, así como observaciones debidamente contrastadas, contemplando además de las plantas vasculares, los briófitos y las macroalgas. El resultado proporcionó 247 taxones diferentes, que corresponden a 61 familias, y cuyo patrón se aparta del que presentan los hábitats mediterráneos típicos. También, a partir de los datos del catálogo, se muestra como en dicho hábitat son escasos los endemismos y predominan las especies con grandes áreas de distribución. Se describen las principales comunidades vegetales de la marisma y cómo se organizan en función del tiempo de inundación de los suelos y de la concentración de sales que estos presentan. Asimismo, se identifican diversos problemas que afectan a la conservación de los ecosistemas del Parque Nacional de Doñana, como la disminución del volumen de agua de la marisma, el deterioro de la calidad de sus aguas y la aparición de especies exóticas invasoras