OPTIMIZATION OF ACOUSTIC SURVEY METHODS FOR HABITAT MAPPING OF THE POSIDONIA OCEANICA ALGAE ON THE EASTERN COAST OF THE ADRIATIC

This study presents a new approach to optimize the habitat mapping process of the Posidonia oceanica algae on the east coast of the Adriatic Sea. Mapping of underwater and coastal habitats in the Adriatic Sea, until now, was conducted by direct methods (diving, drop-down camera, etc.) in combination with indirect modelling, which in the majority of cases results in data heterogeneity. The mentioned approach has proven unreliable, expensive, and only informative. Modern indirect, remote sensing methods enable an analysis of the dispersion of the return acoustic signal in the entire water column, leading to more detailed and effective habitat mapping. Side-scan echo sounder imagery has been extensively used for habitat mapping due to its good seafloor coverage. However, it still has proven to have some limitations (e.g. need for combining with other instruments to collect precise bathymetric data). Multibeam echo sounder enables full coverage of the seafloor, precise bathymetric data, and backscatter data allowing more detailed analysis. On the other hand, a simultaneous hydrographic survey with side-scan and multibeam echo sounder results in superior imagery, better seafloor coverage, and vast and various data sets. This approach requires optimization of the acoustic instruments for collecting detailed data, which can later result in a more successful classification of the Posidonia oceanica underwater habitat. Such methodology has proven to be less time-consuming, more precise, and cost-benefit for future mapping of large sea areas.