Ocean acidification caused by anthropogenic uptake of CO₂ is perceived to be a major threat to calcifying organisms. Cold-water corals were thought to be strongly affected by a decrease in ocean pH due to their abundance in deep and cold waters which, in contrast to tropical coral reef waters, will soon become corrosive to calcium carbonate. Calcification rates of two Mediterranean cold-water c...

We define habitat-forming deep-sea corals as those families of octocorals, hexacorals, and stylasterids with species that live deeper than 200 m, with a majority of species exhibiting complex branching morphology and a sufficient size to provide substrata or refugia to associated species. We present 2,649 records (name, geoposition, depth, and data quality) from eleven institutions on eight hab...

The continental shelf and submarine canyon off Cap de Creus (NW Mediterranean) were declared a Site of Community Importance (SCI) within the Natura 2000 Network in 2014. Implementing an effective management plan to preserve its biological diversity monitor evolution through time requires detailed characterization benthic ecosystem. Based on 60 underwater video transects performed between 2007 2...

Deep-sea stony corals, which can be fragile, long-lived, late to mature and habitat-forming, are defined as vulnerable marine ecosystem indicator taxa. Under United Nations resolutions, these corals require protection from human disturbance such as fishing. To better understand the vulnerability of stony corals (Goniocorella dumosa, Madrepora oculata, Solenosmilia variabilis) to disturbance wit...

Subseafloor sedimentary environments harbor remarkably diverse microbial communities. However, it remains unknown if the deeply buried fossils in these sediments play ecological roles in deep microbial habitats, or whether the microbial communities inhabiting such fossils differ from those in the surrounding sediment matrix. Here we compare the community structures of subseafloor microbes in co...

Benthic fauna form spatial patterns which are the result of both biotic and abiotic processes, can be quantified with a range landscape ecology descriptors. Fine- to medium-scale (<1–10 m) have seldom been in deep-sea habitats, but provide fundamental ecological insights into species’ niches interactions. Cold-water coral reefs formed by Desmophyllum pertusum (syn. Lophelia pertusa ) Mad...

The Lacaze-Duthiers Canyon is located in the western Mediterranean Sea and long known for hosting cold-water coral colonies canyon head region at depths ranging from 250 to 550 m. In 2019 during CALADU cruise, three kinds of 3D-reconstructions were applied better understand distribution colonies, their habitat skeleton morphologies. canyon's flanks mapped using a hull-mounted echosounder an ROV...

Impact of diagenesis on carbonate mound formation This thesis is devoted to define the parameters influencing cold-water coral growth and therefore carbonate mound development with a focus on the impact of diagenesis on mound sediments. The first part of this thesis (Chapters 2 to 4) discusses the distribution and growth history of carbonate mounds, the sedimentary processes leading to sediment...