The Mediterranean Sea is a biodiversity and climate change hotspot. The increase in seawater temperature affects marine ecosystems causing marine species to change their distribution and abundance. Such changes lead to alterations in community composition, often characterized by an increase in warm-affinity species over time, known as tropicalization of temperate seas. Monitoring programmes are useful for understanding the consequences of the ongoing transformations driven by ocean warming. In this study, underwater visual censuses (UVC) were conducted for fish and benthic communities at 24 stations of the Balearic Archipelago in 2022 and 2025. The comparison between both periods revealed an increase in the frequency of warm-affinity species, including the fishes Sparisoma cretense (Teleostea, Scaridae) and Caranx crysos (Teleostea, Carangidae); the invertebrates Telmatactis cricoides (Cnidaria, Actiniaria) and Hermodice carunculata (Annelida, Polychaeta, Amphinomidae) and the algae Penicillus capitatus (Chlorophyta, Ulvophyceae). Our findings highlight the importance of monitoring programmes to identify evidence of processes such as tropicalization and to provide timely information to respond to shifting marine ecosystems.
Ballina et al. (Sat,) studied this question.