Mesophotic habitats, hosting benthic assemblages totally unknown and unexpected in the early 2000s, are attracting an increasing interest from scientists.

The mesophotic zone is characterized by environmental factors generally more stable than the shallow counterpart; therefore, it represents a refuge habitat to preserve species that, in shallow waters, may be involved in bleaching events, massive mortalities or other pathologies generally triggered by thermal anomalies.

Because the definition of the mesophotic zone in the temperate seas is confused, this paper reviews the scientific literature to build the best definition possible based on the maximum consensus coming from papers analysis.

Additionally, the paper schematizes the key roles of mesophotic habitats, including ecosystems engineers as animal forests, to enhance the perception of the potential risks we are running in case of damage or loss of these habitats.

Cerrano et al. (2019) Temperate mesophotic ecosystems: gaps and perspectives of an emerging conservation challenge for the Mediterranean Sea 86:370-388.