Abstract
The mesophotic coral Dendrophyllia ramea is a Vulnerable Marine Ecosystem indicator species occurring in the NE Atlantic and in the Mediterranean, yet protection is unevenly articulated across regions. While studies on its occurrence, biology, and ecology have been published on Mediterranean populations, quantitative information for Atlantic ones is lacking. During the DEEP CANARIES expedition, aimed at partially addressing this gap regarding the Atlantic, an outstanding population of Dendrophyllia ramea was discovered off the southeastern coast of Tenerife (Canary Islands). Here, we document the density and colony-size structure of this exceptional population and discuss the relevance of this finding for the region and the need to protect it. 2 Video sampling was conducted with a remotely operated vehicle, and Dendrophyllia ramea density, occupancy, and colony size were measured. Video records unveiled a dense population, with a maximum density of 9.3 colonies ⋅ m and an occupancy of 37.26% in the area with the highest colony concentration. Large colonies represented the highest proportion of the population, reaching a maximum size of 68.5 cm. Densities and di mensions reported here are consistent with the maximum values recorded for Mediterranean populations, being the densest one documented for the Atlantic heretofore. Considering the potential implementation of an offshore wind farm in the area, the data presented here highlight the urgent need to protect this unique population, expanding the scope of existing regulatory frame works, and extending the species’ inclusion within the Spanish List of Wildlife Species under Special Protection Regime and Catalogue of Threatened Species to Atlantic populations.