Citizen science and 3D modeling to study and protect Mediterranean marine caves: a real application in the caves of the Gulf of Orosei (Sardinia, Italy).

The Mediterranean coastline presents a high number of marine caves of different types. Marine caves are protected by the EU Habitats Directive (92/43/EEC - code 8330). Semi-dark and dark cave communities have been included in two Action Plans by UNEP-MAP-RAC/SPA (2008 and 2015 respectively) and are considered as sensitive reservoirs of biodiversity requiring protection. However, the scientific community still has scarce information about these important habitats, that are listed as Data Deficient.

The main reason for the lack of knowledge about marine caves is that they are very difficult to access and study. Lack of a breathable source, lack of light and a physical ceiling are the hazards characterising any underwater cave; specific locations can force cave divers to deal with limited visibility, restricted passages or high water flow. The number of individuals with the skills required to safely navigate such caves while carrying out research or scientific work is extremely limited.  

Our project aims at closing this information gap, by providing a methodology for surveying underwater caves. Our main study area is the Gulf of Orosei, Sardinia Italy. We count essentially on two important elements: 

• citizen science - over the years, we gained a lot of experience in coordinating groups of volunteers, working with professional scientists to achieve common goals. All our projects and missions are carried out with the precious involvement of skilled individuals that perform specific tasks.
• advanced technology - technology is essential to gather information about underwater environments in general, and caves in particular. Photogrammetry is the most detailed methodology to create a multidimensional cave model. Thanks to the precision and the very realistic representation of the environment, these models are ideal for both scientific and dissemination purposes. Photogrammetry relies on the connection between polygon line survey and photographic data. We can split the procedure in three parts: data collection (survey and media), software processing and model refinement. Once the model is finished, there are many useful applications that can be considered. For scientific purpose, the model can be geo-referenced and can be scaled and calibrated by a variety of methods to allow measurements and further analysis of the cave environment and surrounding landscape. For publication purposes to the wider public, the model can be exported to graphical design or ‘animated’ with VR and gaming softwares. Annotating the model and any artifact inside it with information can entertain and educate the visitors in virtual reality.

Possibilities are endless and to fully master the flow from data capture inside the cave down to an interactive virtual representation or a scientific survey, a lot of expertise and knowledge is required and a strong cooperation between cave divers and researchers.

References:
Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000;
Directive 2006/118/EC of the European Parliament and of the Council of 12 December 2006;
Global Wetland Outlook: State of the World’s Wetlands and their Services to People. Gland, Switzerland: Ramsar Convention Secretariat (2018);
European Red List of Habitats (ISBN 978-92-79-61586-3; ISBN 978-92-79-61588-7).