Croatian Coralligenous monitoring protocol: the basic methodological approach

Development of the national coralligenous monitoring protocol has been recently initiated in Croatia in the framework of the MedMPAnet project, with intention to primarily fulfill reporting and monitoring requirements of the EU Habitat Directive (92/43/EEC). However, basic information on coralligenous habitat along the Croatian coast is still lacking, which hinders a fixed definition of the monitoring methods and metrics to be used. Instead, we propose the basic methodological approach that will enable gathering the information needed and that will serve as a basis for reformulation of the adopted methods. The proposed monitoring protocol is based on the most recent (although scarce) knowledge on the monitoring approaches for this habitat, the compilation of available information for the coralligenous thriving along the Croatian coast as well as on the results of the fieldwork devoted to testing of the monitoring methods within the project. At each site, photosampling of minimum of three areas of 2.5 m2 (comprised of 10 contiguous photos of 50 x 50 cm quadrats to ensure species identification) will be combined with visual census along 10 m long horizontal transects, to gather information on habitat structure and function (species composition, habitat complexity, bioconcretion and bioerosion), as well as on the degree of impact of the main disturbances (mass mortalities, invasive species, sedimentation, mucilaginous aggregates, fishing gear). Down to 40 m depth this work will be carried out by SCUBA divers whereas the use of the Remote Operate Vehicles (ROVs) is envisaged at greater depths. The obtained information will both enhance knowledge on the coralligenous habitat along the Croatian coast and will provide an original data set to validate future indices of coralligenous health status, currently under development within other Mediterranean initiatives.