Changes in biogeographic patterns of coastal benthic decapods: Indicators of tropicalization in the Canary Islands over the last 50 years

The Canary Islands constitute one of the major marine biodiversity hotspots in the eastern-central Atlantic, with decapod crustaceans being a highly representative group in the benthic environment due to their vast diversity of taxa and occupied ecosystems. This study identifies three significant milestones corresponding to the publication of comprehensive decapod checklist for the Canary Islands in 1973, 1995, and 2018. The lists of coastal benthic decapod species (0–300 m depth) were revised and updated, indicating the biogeographic pattern and vertical distribution range of each species in the region. Changes in the composition of the biogeographic patterns of coastal decapods in the Canary Islands were analysed to evaluate whether they could be considered as a useful indicator of the tropicalization process in the region. Particular attention was paid to variations in the percentages of species with warm water affinity versus those with Atlanto-Mediterranean preferences, with the former showing a clear upward trend.