Assessing the Environmental Status of five Sardinian black corals forests via Mesophotic Assemblages Conservation Status Index (MACS)

Marine animal forests are important mesophotic habitats threatened by an increasing number of natural and human pressures. Although several international agreements aim to protect these vulnerable ecosystems, the Environmental Status of most of these benthic animal-structured habitats remains unknown. Based on ROV footage, we evaluated the Environmental Status of 5 black corals forests in the center of the Western Mediterranean Sea, through the Mesophotic Assemblages Conservation Status (MACS) Index. The MACS index combines two independent indices: the Index of Status of the benthic communities, analyzing conspicuous species diversity, basal layer and canopy composition; the Index of Impact, analyzing siltation level, canopy condition and marine litter occurrence. The five investigated sites are characterized by the presence of two Antipatharians, Antipathella subpinnata and Leiopathes glaberrima, dwelling in different environmental conditions. Four sites showed high and good values of the Index of Status, and only one site showed a moderate status. Regarding the Impact Index, four sites were classified with low values, except one showed a very low value. Overall, four black forests were classified in a Good and one in a Very High Environmental Status. Assessing the Environmental Status is the first step needed to monitor these essential habitats' health over time and improve the current frameworks for their conservation and protection, such as the Marine Strategy Framework Directive.