Study Areas

Cabliers CWC Reefs

CWC reefs are located in the Alboran Sea, wester Mediterranean. These reefs lay on top of the Cabliers coral mound province (CCM). The CCM is a field of long ridge-like mounds, up to 110 m tall, entirely built by CWC framework and sediments, which started to form at least 400.000 years ago. It extends NNE-SSW for 25 km, laying on the volcanic bedrock within a depth range of 260-710 m. Fine scale seafloor mapping revealed original and spectacular bio/geomorphologies on the mound, forming small mounds and whose intriguing forms and relative shaping processes are still far from being entirely understood. ROV analysis confirmed that the small mounds correspond to M. oculata and L. pertusa reefs, found in exceptional thriving conditions. This is by itself an exceptional finding, as framework building CWCs in the Mediterranean Sea are generally represented by small populations or scattered patchy colonies, e often found in a poor state of conservation due to the impact of fishing activities and pollution, or to natural changes of environmental conditions during past geologic periods The well preserved state of conservation and large extension (over 5 km) of scleractinians and associated communities on Cabliers, dimension of the largest colonies (L. pertusa colonies are up to 3 m large), and the occurrence of fish populations dominated by juveniles, demonstrating these reefs serve as nursery area for various species. HABISS scietnfic tasks will count with a new dataset acquired ad-hoc during the OASIS Cruise, awarded by the H2020 Eurofleets+ Project. The high environemtal relevance of this study area is reflected in the future creation of a Fisheries Restricred Areas (FRA) on Cabliers reefs, managed by the United Nations General Fisheries Commission for the Mediterranean.

Inflowing Atlantinc Water

Blanes Canyon CWC fields

The Blanes Canyon is a shelf incising canyon located in the NW Mediterranean. His head breaches the shelf at a depth of 50 m and about 5 km from the coast. Blanes Canyon is about 60 km long and half a kilometer wide, descending to approximately 2300 meters in depth. Its wide and complex vertical walls, suggesting a strong tectonic control in its generation, host extensive and dense colonies of deep cold water corals, forming an unexpected hotspots of biodiversity, a shelter to numerous fish and juvenile crustaceans, with numerous species of coral and associated gorgonians, some of them protected and in danger of extinction. These CWC communities are found in good conditions, despite the proximity of the fishing grounds a few hundred meters away. Industrial bottom trawling along Blanes Canyon periodically moves sediments up the slope, from the canyon flanks, where the fishing grounds are located, to its axis, where they end up accumulating. Distribution of CWC fields point out that the canyon’s vaulted walls may offer protection from falling sediments. It is not known what effect such a sediment shower may have on the coral communities and how this anthropogenic process may affect the natural mechanisms maintaining them. To find out, the scientists have installed five anchors with oceanographic instruments in different parts of the canyon, which recorded the sedimentary dynamics around these communities and which are part of HABISS dataset.

Barkley Canyon CWC fields

Barkley Canyon is located in the NE Pacific, about 100 km offshore from Vancouver Island, British Columbia, Canada. The canyon extends from the edge of the continental shelf at 200 m, up to the Cascadia Basin at around 2000 m. Barkley canyon is bathed by the NE Pacific oxygen minimum zone (OMZ) at intermediate depths (400–1000 m), which is expanding as a consequence of global warming.  It is observed that low concentrations of dissolved oxygen (DO) act as natural stressors for deep-sea coral ecosystems. Nonetheless, recent findings in Barkley Canyon showed a surprisingly well-structured megabenthic community found at 780-1000 m deep cliffs in the severe hypoxic waters of the canyon.  HABISS will take profit of decade-long time-series from Ocean Networks Canada’s NEPTUNE cabled seafloor observatory to better understand the oceanographic, hydrodynamic and sedimentary dynamics which allow Barkley CWC assemblages to cope with extreme low concentration of dissolved oxygen, and adapt to changing environmental conditions, in response to long-term climate change.