Study areas
iAtlantic was underpinned by an extensive field programme comprising more than 30 research expeditions that collectively spanned the length and breadth of the Atlantic Ocean. Drawing on a multinational fleet of research vessels and the latest marine technology and instrumentation, our efforts focussed mainly (but not exclusively) on 12 locations in the deep sea and open ocean that are of international conservation significance and of interest to Blue Economy and Blue Growth sectors. Use the map below to find out more about the areas of the Atlantic that we explored, and visit our expeditions page to learn about our activities at sea.
Subpolar MAR open-ocean ecosystem off Iceland
Abyssal plain and deep-sea coral banks from the Rockall Trough to the Porcupine Abyssal Plain
Deep-sea coral and hydrothermal vent ecosystems, central MAR
Deep-sea canyons and open-ocean ecosystem, NW Atlantic
Subtropical open-ocean ecosystem of the Sargasso Sea
Eastern tropical North Atlantic, Cabo Verde
Equatorial deep/open ocean fracture zones
Continental slope, margin and cold seep ecosystems – Angola to the Congo Lobe
Abyssal plains and deepsea ridge ecosystems of the Benguela Current from the Walvis Ridge to South Africa
Deep-sea continental slope, banks and cold seep ecosystems off Brazil
Vitória-Trindade Seamount Chain off Brazil
Deep-sea coral banks in the Malvinas Upwelling Current off Argentina.
1. Subpolar Mid-Atlantic Ridge (MAR) open ocean ecosystem off Iceland
This part of the Atlantic comprises a wide range of benthic (seafloor) and pelagic (water column) ecosystems that live on the continental shelf and slope, the mid-ocean ridge and surrounding abyssal plains. Vulnerable Marine Ecosystems (those that are particularly sensitive to disturbance by activities such as fishing) are primarily found on the shelf, slopes and ridges in Icelandic waters. The area is heavily influenced by major oceanographic features – the warm Atlantic water masses and the cold waters of the East Greenland Current and the East Iceland Current – which have a profound influence on the primary productivity and functioning of marine pelagic wildlife, such as whales, zooplankton and fish.
Right: Humpback whale breaching offshore Iceland. Image courtesy S. Ragnarsson.
2. Abyssal plain and deep-sea coral banks from the Rockall Trough to the Porcupine Abyssal Plain
This study area reaches from the northern Rockall Trough, along the Atlantic margins of the UK and Ireland, down to the centre of the Porcupine Abyssal Plain. The area is home to cold-water coral reefs, submarine canyons, seamounts and banks, each with their own biological communities. A long-term ocean observatory on the Porcupine Abyssal Plain gives insights into the environmental changes that this northern sector of the Atlantic has experienced over time, while oceanographic moorings and annual ocean measurements along the Extended Ellett Line across the Rockall Trough provide invaluable input data for the oceanographic models that estimate the flux of heat and carbon through the NE Atlantic.
Left: Diverse benthic fauna on the flanks of Rockall Bank, 770 m water depth. Image courtesy NOC.
3. Deep-sea coral and hydrothermal vent ecosystems, central Mid-Atlantic Ridge
The spine of the Atlantic, the Mid-Atlantic Ridge is where new ocean crust is formed as plate tectonics pull the two sides of the Atlantic Ocean apart. In a narrow zone along the axis of the ridge the heat from volcanic activity drives hydrothermal venting at the seafloor, which supports a unique and diverse ecosystem that includes specialist chemosynthetic organisms and species that can tolerate the harsh conditions in and around the active hydrothermal vents. On the rocky flanks of the ridge and nearby seamounts, deep-sea corals attach themselves and feed on the organic-rich detritus brought in on the ocean currents. Mid-ocean ridge ecosystems are potentially at risk from the emerging deep-sea mining industry, which is set to target seafloor massive sulphide deposits that occur along the mid-ocean ridge.
Right: hydrothermal vent fauna at the Snake Pit vent field, Mid-Atlantic ridge. Image courtesy Ifremer/Victor 6000, Bicose 2014.
4. Deep-sea canyons and open-ocean ecosystems, NW Atlantic
The continental slopes form the oceanic rim, surrounding the deep ocean basins and supporting ecosystems distinct from, and yet connected to, those of both the basins and the continental shelves. The slopes are furrowed by submarine canyons, which provide important pathways connecting the shelves to deep ocean and often support rich biodiversity, from cold-water corals to deep-diving whales. The Gully, off Nova Scotia, is the largest canyon incised into the western margin of the North Atlantic and is Canada’s “flagship” Marine Protected Area. With its subsidiary canyons, the surrounding continental slope and the adjacent volume of the deep Atlantic, the area centred on The Gully provides a prime example of the inter-connected ecosystems around the oceanic rim.
Left: The rocky substrate of the Gully submarine canyon in the NW Atlantic is home to a diverse and colourful fauna. Image courtesy DFO.
5. Subtropical open-ocean ecosystems of the Sargasso Sea
This subtropical open-ocean ecosystem is bounded by four different ocean currents, which form an ocean gyre. The Sargasso Sea plays a crucial role in the wider North Atlantic ecosystem as habitat, foraging area, spawning ground and important migratory corridor, and is named after the endemic Sargassum seaweed that is found here. This sea is a haven for biodiversity, and is recognised as an Ecologically or Biologically Significant Area by the UN Convention on Biological Diversity. It is the planet’s only sea without a land boundary.
Right: The Sargasso Sea is an import area for megafauna like the humpback whale. Image courtesy Andrew Stevenson.
6. Eastern tropical North Atlantic, Cabo Verde
The large marine ecosystem in the Eastern Tropical North Atlantic (ETNA) off West Africa is among the most productive, diverse, and economically important marine regions worldwide due to a strong ocean-atmosphere coupling. Massive amounts of Saharan dust are deposited every year onto the sea, fuelling biological productivity in the ocean. But other major ocean processes are at work here too. The coastal upwelling system off West Africa – where cold, nutrient-rich waters well up from ocean depths – also feeds the marine ecosystem, and the seamounts around Cabo Verde are hotspots of marine biodiversity.
However, a harmful oxygen minimum zone exists in the ocean’s interior, which in the Atlantic is not yet as pronounced as its counterparts in the Pacific and Indian oceans, but in recent decades has shown trends of expansion and could become a challenge for marine life in the region.
Left: Saharan dust offshore Mauritania and around the Cape Verdes. Image courtesy NASA MODIS Rapid Response Team, Michon Scott
7. Equatorial deep/open ocean fracture zones
The Romanche Fracture Zone is a prominent geological feature known as a transform fault, which offsets the line of the Mid-Atlantic Ridge axis by about 900 km – the largest such offset in the Atlantic. The fracture zone manifests at the seafloor as long and deep valley reaching 7,000 m water depth, which acts as the main conduit for the flow of deep water masses between the North and South Atlantic basins. Seafloor habitats are shaped by the crests and ridges that flank the valley, but also include flatter sediment-covered areas and gentle slopes. These habitats are influenced by a high flux of organic matter from phytoplankton blooms caused by seasonal equatorial upwelling. Such high productivity in the middle of the vast oligotrophic (nutrient-poor) zones of the subtropical north and south Atlantic is thought to have an ‘oasis’ effect, enhancing abundance and diversity of marine life in and around the Romanche Fracture Zone. As such, it has been identified as an Ecologically and Biologically Significant Area by the UN Convention on Biological Diversity, and is of high conservation interest in light of the developing deep-sea mining industry.
Right: Catch from a scientific trawl in the Romanche Fracture Zone during the MAR ECO expedition in 2009. Image courtesy A. Barreto, UNIVALI.
8. Continental slope, margin and cold seep ecosystems – Angola to the Congo Lobe
The complex oceanic currents in this part of the Atlantic result in the widespread occurrence of strongly oxygen-depleted subsurface water masses. Despite such seemingly unfavourable conditions, diverse benthic ecosystems thrive along the Angolan continental slope, including cold-water corals and cold seep ecosystems. While the corals are fuelled by organic matter filtering down from surface plankton productivity, the cold seep ecosystems obtain their energy from natural methane emissions at the seafloor.
As oxygen levels in the world ocean are predicted to decrease as a result of global change, the subtropical SE Atlantic can serve as a natural laboratory to understand how deep-sea marine ecosystems adapt to low oxygen conditions and, thus, to cope with one of the most serious threats to marine ecosystems.
Left: Cold-water coral reef in the hypoxic waters off Angola. Image courtesy MARUM.
9. Abyssal plains and deep-sea ridge ecosystems of the Benguela Current from the Walvis Ridge to South Africa
The Benguela Current is an important ocean current that flows northwards along the coast of South Africa, Namibia, and Angola. The current mixes water from the Atlantic and Indian Oceans as they meet off the capes of South Africa, and is driven northwards by the prevailing south-easterly winds. These winds are also responsible for generating oceanic upwelling, resulting in high biological productivity that supports rich fish stocks.
Running from the African coast to the southern mid-Atlantic Ridge is a prominent chain of volcanic seamounts known as the Walvis Ridge. This ridge not only forms a significant physical barrier, creating a range of oceanographic phenomena, but also creates a variety of habitats that host a wide diversity of species and ecosystems.
Right: The Walvis Ridge, stretching SW from the coast of Namibia, is a prominent bathymetric feature in the SE Atlantic Ocean. Image courtesy NOAA.
10. Deep-sea continental slope, banks and cold seep ecosystems off Brazil
The continental margin off SE Brazil comprises the Santos and Campos sedimentary basins, which sustain some of the world’s most intensive oil and gas exploitation activities. These basins were formed nearly 100 million years ago, back when the South Atlantic was a narrow marine environment between South America and Africa. The region is characterised by extensive deep sedimentary environments and pockmark fields, where it is speculated that natural gas may be emitted from the seabed and potentially sustain chemosynthetic ecosystems. There are also steep rocky slopes that are home to important cold-water coral reef systems, irregularly threatened by fisheries activity. Many knowledge gaps exist in this region, and filling them is critical for responsible management of current and future human activities.
Left: Deep rover submersible illuminates a deep pockmark from the top of a carbonate mound in Santos Basin. Photo courtesy Alucia Productions.
11. Vitória-Trindade Seamount Chain off Brazil
The Vitória-Trindade Chain of seamounts extends some 1200 km from the eastern continental shelf of Brazil out to the oceanic islands of Trindade and Martin Vaz. These 17 seamounts rise up around 2,500 m from the seafloor, topping out at between 50-110 m below the sea surface, and are home to reef ecosystems and associated fish communities. Seamounts are generally known to be hotspots of biological diversity, but relatively little is known about the marine life around these undersea mountains.
Right: The Vitoria-Trindade Chain is best known for its diverse reef fish communities. Image courtesy H.Pinheiro et al/Wikimedia Commons CC BY 4.0
12. Deep-sea coral banks in the Malvinas Upwelling Current off Argentina
Along the seaward rim of the wide Argentinian shelf in the SW Atlantic, huge amounts of nutrients are brought up from the ocean depths via oceanic upwelling. These nutrients support high marine phytoplankton productivity, which in turn fuels diverse ecosystems at the seabed. Recent discoveries reveal that one of the most diverse group of deep-sea ecosystems – cold-water coral reefs – benefits from this abundant food supply. These Argentinian cold-water coral reefs are unique as they are built by an ecosystem engineer, the cold-water coral Bathelia candida, which is found nowhere else in the Atlantic Ocean.
Left: The cut surface of a sediment core collected off Argentina showing abundant fossil cold-water coral fragments embedded in fine-grained deep-sea mud. Image courtesy D. Hebbeln.
© 2024 iAtlantic. All rights reserved.
This project received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 818123 (iAtlantic). This output reflects only the author’s view and the European Union cannot be held responsible for any use that may be made of the information contained therein.