Monitoring Fish Diversity: A Case Study Using Remote Underwater Video Surveys in the Aegean Sea

The Mediterranean Sea hosts a plethora of fish species, occupying a wide variety of ecological niches and environments. These crucial habitats, such as seagrass meadows and rocky reefs, are often at high risk of degradation, primarily due to anthropogenic stressors. While biodiversity in the Mediterranean basin is overall well studied, fish assemblages of the North Aegean islands have received less attention to date. Here, we used remote underwater videos (RUV) to assess the richness and abundance of the fish species populating Posidonia oceanica seagrass meadows and rocky reefs around two island in the Aegean Sea, Lipsi and Samos. The results show overlap of niches for most species, while also highlighting the presence of habitat-specific taxa. Six species were found on both islands, in both seagrass and rocky habitats. The presence of three species, namely Diplodus annularis, Labrus viridis, and Sarpa salpa, appeared to be significantly correlated with the habitat type. This study represents a preliminary assessment of fish biodiversity in the Aegean Sea through the use of RUV data. While further data are needed to conclusively evaluate differences between habitat types, this study provides baseline information to establish conservation and management plans.