The Project “Caulerpa cylindracea in the Egadi Islands”: citizens and scientists working together to monitor marine alien species

The creation of early-warning systems is crucial for preventing and reducing the risk of invasive species introduction. In this respect, the contribution of citizen-scientists (tourists, students, teachers, divers and fishermen) in providing information and data (validated by taxonomic experts) on the occurrence of marine invasive species that would otherwise be impossible to collect, is crucial in understanding the phenomenon of biological invasions. The Citizen Science Project “Caulerpa cylindracea - Egadi Islands”, launched in 2014 and ended in 2016, aimed at creating a database on the spread dynamics and the levels of threat of the invasive green alga Caulerpa cylindracea within the Egadi Islands Marine Protected Area (MPA). The Project registered numerous followers and different groups of volunteers (students, tourists, divers, underwater photographers, amateurs and fishermen) were involved. In all 156 sightings (18 Divers, 9 Researchers, 91 Citizens, 38 Scientific Team) were collected. The alga was reported from all the three main Islands even though the majority of the records were from Favignana Island. Useful information on the behaviour strategies of the alga was also gathered.