Do black corals occur randomly across the Canary Islands?

Authors:

F Otero-Ferrer, R Aguilar, L Terrana, L Bramanti, M Bo, D Deriu, F Espino, NE Bosch, S Gobbi, Under The Pole Consortium, A García-Mendoza, R Haroun, F Machín, F Tuya, S Navarro-Mayoral. Progress in Oceanography (2026) 

Article summary:

Despite their ecological role as Marine Animal Forest forming species, black corals are understudied and do not escape anthropic threats (bottom trawling, deep-sea mining…). The lack of knowledge and understanding of their spatial distribution is a major obstacle to improvement of their conservation.  

Canary Islands host stunning black coral forests. This volcanic archipelago is extended on 1300 kms: islands are distributed along a western-eastern axis and an oceanographic and geomorphological gradient, thus being known as a “biodiversity crossroad between Atlantic and Mediterranean bioregions”. The archipelago is an “exceptional natural laboratory”, providing a high variety of different habitats for black corals. 

In this study, authors aimed to highlight the importance of black corals across the archipelago and provide the first “comprehensive map” of their distribution; in other words, to know where they are and “understand the conditions that make their presence possible”. Authors analyzed data collected between 2002 and 2024 through ROVs, towed underwater cameras and scuba divers, including data collected by Under The Pole during the DEEPLIFE mission in 2022, representing in total 6 548 presence/absence records of black corals on 144 sites, between the surface and 1000 meters deep.  

11 different taxa were identified to the genus or species level. Their distribution differed between eastern/central versus western islands, showing the influence of the oceanographic and geomorphological gradient mentioned earlier. Moreover, for the most common species, the main drivers of their distribution were depth and substrate (hard or soft). In a lesser way, current velocity and slope of the seabed also influenced the distribution on black corals, in different ways depending on the taxa. In the mesophotic zone, for example, Antipathella wollastoni and Antipathes furcata favor rocky substrates over sandy ones, but A. furcata prefers steeper slopes than A. wollastoni.  

This first “comprehensive map” highlights the importance of black corals across the archipelago and especially in the mesophotic zone, and confirms that they are not randomly distributed. This work will help stakeholders with the regulation of human activities (fisheries, wind farms…), help predict distribution of black coral in unexplored zones, and will contribute to build adapted conservation and management tools.