Observadors del Mar, an emerging reference in marine citizen science

Observadores del Mar is a marine citizen science platform launched in 2012 devoted to enhancing the understanding of the conservation status of marine ecosystems. The platform hosts different projects reporting information on two main topics: i) biodiversity data focusing mainly on species distribution and abundance, and ii) the impacts of anthropogenic activities, including both the occurrence of episodic events (e.g. jellyfish blooms) and associated mid- to long-term changes (e.g. colonization of invasive species). At present Observadores del Mar includes 14 projects covering 8 main taxa: corals, jellyfishes, decapod crustaceans, fishes, seaweeds, seagrasses, seabirds and molluscs, in addition to two projects focused on marine litter. The platform provides information on the rationale, methods and materials for each project. A new web interface was designed to facilitate data entry and enhance data validation by scientists. Moreover, different functionalities were developed to build the Observadores del Mar community. Beyond the web tools, Observadores del Mar has been also very active in promoting citizen science events, training sessions for recreational divers, schools and the general public. Currently the Observadores del Mar platform has almost 3000 volunteers, +250 entities (including more than 40 schools) and 60 scientists from more than 40 research institutions and universities. More than 13000 observations have been already collected resulting in the publication and presentation of more than 20 scientific papers and communications. The major findings have been new records of introduced and invasive species, tracking the spread of novel pen shell mortality outbreak in the Mediterranean Sea and monitoring microplastic concentrations on beaches. Furthermore, some of the information gathered was transferred to public administrations to inform management and action plans at different levels. In conclusion, Observadores del Mar is providing reliable and relevant scientific information while allowing citizens to collaborate and get involved in marine sciences, thus facilitating the interaction among different stakeholders aiming to work for a healthy ocean