The most important marine bioconstructions are coral reefs, which are well known as biodiversity hot-spots. Coral reefs mainly occur in the oligotrophic waters of the western Atlantic and Indo-Pacific regions, within the latitude of 30ºN and 30ºS.

This study describes, for the first time in the Mediterranean Sea, a mesophotic coral reef. This bioconstruction extended for 2.5 km along the Italian Adriatic coast in the bathymetric range -30/-55 m. It appeared as a framework of coral blocks mostly built by two scleractinians, Phyllangia americana mouchezii and Polycyathus muellerae, which were able to edify a secondary substrate with high structural complexity.

The authors state that the species composition of the benthic community showed a marked similarity with those described for Mediterranean coralligenous communities and it appeared to be dominated by invertebrates, while calcareous algae, which are usually considered the main coralligenous reef-builders, where poorly represented.

The authors suggest that, because of the absence of algal symbionts in the corals, heterotrophy had a major role in the metabolic processes that supported the production of calcium carbonate.

Overall, the authors highlight that the studied reef can be considered a unique environment, to be included in the wide and diversified category of Mediterranean bioconstructions.

https://www.nature.com/articles/s41598-019-40284-4.pdf

Corriero et al. (2019) A Mediterranean mesophotic coral reef built by non-symbiotic scleractinians. Scientific Reports 9:3601.