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The margaritona(Margaritifera auricularia) is included in the Red List of the International Union for Conservation of Nature (IUCN) in the “Critically Endangered” category. The Mediterranean naiad(Unio mancus) is included in the “near threatened” category and has a very limited range. Both are valuable bioindicators of the quality of the water in which they are found.

The aim of this project is to contribute to the recovery plan for Margaritifera auricularia by maintaining and studying the growth of juveniles from the Aragon area in order to analyze the problems of reproduction in captivity and potential future reintroduction experiences. In addition, habitat conservation actions for Unio mancus are included, promoting land stewardship for the species. The environmental DNA detection technique has also been used as a tool for monitoring naiad populations and studying their distribution, carrying out profiles and validating their effectiveness during the development of the project.
Finally, understanding that the conservation of an endangered species is not possible if environmental education is not included as a basic tool for the execution of the project, we have included volunteer actions and the publication of educational material aimed at all educational levels.

The general objective of the project has been to contribute to the conservation of the margaritona(Margaritifera auricularia) and the Mediterranean naiad(Unio mancus) and to prevent their decline in Spain.

The specific objectives were as follows:

• Contribute to the captive breeding program of Margaritifera auricularia contemplated in the national and regional recovery plan for the species.
• Use environmental DNA analysis for monitoring and conservation of naiad populations and early detection of invasive species that threaten them.
• Promote land stewardship as a tool for the conservation of Unio mancus naiad habitats.
• To raise awareness of the importance of conserving naiads and their main threats among the general population and to involve them.

• Maintenance and growth study of juvenile Margaritifera auricularia at the Camadoca Center.
• Development of environmental DNA profiling for 4 species of naiads in Spain and predatory invasive species and analysis of samples to validate its effectiveness in the population study.
• Increase in the number of current populations of Unio mancus in the Llobregat river basin in land stewardship areas through the habitat restoration (the Lluçanesa stream, the Relat stream and the Molino de Villalta canal) and of the captive breeding and performances of restocking of the species.
• Early detection and control of signal and red crabs in areas where they are already established, to avoid naiad predation.
• Awareness-raising and environmental volunteer actions for the conservation of naiads: workshops, crayfish removal volunteers, naiad planting volunteers and environmental education visits to the Camadoca center.
• Dissemination and communication of the project through publications in social networks, press releases, a scientific article, informative material, etc.

“The River Goddesses” is a conservation project for the critically endangered IUCN Red List margarita(Margaritifera auricularis) and the Mediterranean naiad(Unio mancus), also threatened.

Regarding the first species, the project has contributed to increase the knowledge on the maintenance of juveniles born in the Aragon breeding center. As for the second species, the validity of new methodologies for captive breeding has been ratified, multiplying by 10 the success obtained in previous experiences. The populations of both species have also been monitored through the usual survey methods, but also through environmental DNA. Likewise, more than 25 kilometers of river have been studied and censused in the surveys carried out during these two years of the project to study population densities of Unio mancus.

On the other hand, 300 meters of riverbed have been restored and 4 settlements have been recovered for Unio mancus (with a total of 1,100 individuals), in six farms where the entity has agreements of land stewardshipThe company believes that this has demonstrated the value of this tool for the habitat conservation of the Naiads. A channel was also repaired to prevent water losses and the riverbank vegetation, as well as the water storage capacity in some sections of the river, riverbank trees have been planted and a protective fence was installed in the same plantation. Another way to restore the habitat of these mollusks has been to control invasive crab populations, especially the signal crab(Pacifastacus leniusculus), capturing a total of 16,352 individuals in the sections with naiad populations.

Finally, several volunteer and environmental education activities have been carried out and educational materials on naiads have been developed and sent to schools in Catalonia and Aragon. In addition, a day of workshops on the conservation of ecosystems and endangered fauna was held, and a brochure was published in digital format to inform about land stewardship among landowners and entities for the management of habitats for naiads and other endangered species. Likewise, environmental volunteer days have been held with school students for the planting of riparian vegetation.