An international exploratory study of the macro and megfauna of the mid-Atlantic Ocean including the processes that control their distribution and community structures.
Odd Aksel Bergstad
Odd Aksel Bergstad, Dr. scient., Institute of Marine Research, Flødevigen, Norway
Patterns and Processes of the Ecosystems
of the Northern Mid-Atlantic
• What lives along the mid-ocean ridges, the world’s youngest mountain chains?
• Do mid-ocean ridge waters have particular animal communities, different from those inhabiting adjacent ocean basins and continental margins?
• Are abundance and biomass elevated along ridges?
• How can we conduct research in such an extreme environment?
• What is the significance of ridges for regional ecosystems and global oceans?
• What scientific information is needed to facilitate sustainable human use and conservation of mid-ocean resources and habitats?
Increasing interest is focused on regions and habitats of the world's oceans that remain relatively unexplored. Mid-ocean ridge systems are huge deep ocean features that fall into this category. The global ridge system is around 60,000 km long, and constitutes the world’s youngest and longest ‘mountain chain’. Ecological studies were only conducted along short sections of this enormous system, and inventories of ridge-associated organisms are scattered and incomplete. Mid-ocean ridges are prominent topographic features affecting ocean circulation patterns and thus distribution patterns of marine life forms.
Ridges are found in all oceans. In the North Atlantic, the mid-Atlantic Ridge is a prominant mid-ocean feature.Image credit: NOAA NODC.
Since the late 1970s considerable research efforts were devoted to studies of newly discovered chemosynthetic system, such as those sustained by hydrothermal vents occurring on mid-ocean ridges. Within the Census of Marine Life, the ChESS project focused on such systems whereas MAR-ECO studied organisms and food-webs relying on photosynthesis. While vent communities are scattered and relatively localised, communities sustained by photosynthesis (i.e. the process whereby green plants synthesise organic carbon using sunlight at energy source) are everywhere and thus most significant for the overall biological production at regional and global scales.
MAR-ECO aimed to describe and understand the patterns of distribution, abundance and the trophic relationships among the organisms inhabiting the waters over and around the mid-Atlantic Ridge. It also aimed to identify and model the ecological processes that cause variability in these patterns. The project chiefly focused on fish, crustaceans, cephalopods, and gelatinous plankton, but epibenthos of many taxa, and top predators such as seabirds and cetaceans also received attention.
MAR-ECO used many technologies and platforms to investigate deepwater life.
Here an underwater viedo profiler is launched from a research vessel.
MAR-ECO faced severe technological challenges. Data collection and observation at great depths and in rugged terrain was difficult and required many technologies, which ideally were available at the same time. The project combined classical sampling techniques using nets and trawls with modern remote sensing technology (acoustics, optics). In addition to modern high-seas research vessels many other platforms carried advanced instrumentation (e.g., towed vehicles, moorings, free-fall landers, manned and unmanned tethered vehicles, satellites). Many different international technology companies collaborated with researchers to develop and test state-of-the-art equipment that rose to these challenges.
The study area included the Mid-Atlantic Ridge and the adjacent waters from the Azores to Iceland. Research expeditions surveyed much of the area using acoustics, optical profilers, and depth-stratified sampling by plankton nets and mid-water trawls. Three sub- areas were selected for more intensive sampling and observation by traditional and novel methods and technologies, and sampling and visual observation on and near the sea-bed. Particular focus was given to the middle box characterised by the double cross-ridge rift named the Charlie-Gibbs Fracture Zone and a hydrographical feature known as the Sub-polar Front.
MAR-ECO’s field efforts were concentrated in two phases, 2003-2005 and 2007-2010, and involved a number of research cruises on several vessels committed by national governments and sponsored by several agencies: Icelandic and Russian (June 2003), the Russian MIR submersibles (summer 2003), the Norwegian RV G.O. Sars (two months, summer 2004), the chartered fishing vessel Loran, and UK and US vessels in 2007-2010. Data and samples were also obtained from Portuguese and German vessels conducting other but related investigations. The final expedition was conducted in June-July 2010 on the UK vessel RRS James Cook operating the remotely-operated vehicle Isis in the Charlie-Gibbs Fracture Zone. This effort, carried out by the UK wing of MAR-ECO named ECOMAR, constituted a major final visual documentation of benthic communities and habitats in that fascinating area, first visited by US-Russian colleagues diving in the MIR submersibles in 2003.
Onshore analyses were extensive, and biological collections and data from the expeditions form the basis of numerous publications and syntheses under the auspices of the Census of Marine Life. Data were submitted to the Ocean Biogeographic Information System (OBIS) and the Barcode of Life. New distribution and abundance data were available for around 1000 species, and by mid-2010 MAR-ECO partners had described 32 new species to science, and more are likely to follow. Community structure of the midwater and bottom –living macro-and megafauna was described in several papers. Several unexpected features were observed, such as a concentration of midwater fauna along ridge slopes and unusual significance of bathypelagic food-webs. A strong influence of hydrographical fronts and eddies on distribution patterns at various spatial scales were also important new findings.
Major contributions from MAR-ECO to the ‘picture of biodiversity’ created by the Census of Marine Life were:
• Revised species inventories for the pelagic and demersal macro- and megafauna of the mid-ocean North Atlantic (Iceland-Azores section) based on MAR-ECO results and other sources.
• Revised range descriptions (and geo-referenced occurrence data in OBIS).
• Descriptions of new species from a number of taxa.
• New information on patterns of distribution and abundance at population and community level, with revised hypothesis that can form basis for studies in other geographical areas.
• Conceptual models and graphical outputs that synthesizes overall patterns.
• New information on genetic composition and population structure for deepwater species, especially fishes.
• New information on life history diversity of selected invertebrate taxa and fishes.
The new insight and technological experience gained from the North Atlantic study can be used to generate hypotheses and theories to be tested in other waters in subsequent projects.
The information learned concerning exploited resources and biodiversity was of immediate value to global advisory authorities such as the International Council for Exploration of the Seas (ICES) and national research institutes, in turn benefiting regional management authorities such as the Northeast Atlantic Fisheries Commission (NEAFC) and the Oslo-Paris Commission (OSPAR). Enhanced knowledge on the mid-ocean ecosystems is critical to ensuring sustainable use and conservation of the oceanic environment and resources. Information derived from MAR-ECO was used as a significant scientific basis for recent decisions by NEAFC to close major sections of the mid-Atlantic Ridge to bottom fishing, and for OSPAR proposals to create mid-ocean maritime protected areas.
MAR-ECO expanded geographically. A spin-off project, which is remaining beyond the 2010 closure of the North Atlantic MAR-ECO, is underway in the South Atlantic. Led by a South American-African consortium, a dedicated cruise to the very unknown South Atlantic section of the mid-Atlantic Ridge was conducted in 2009 on the Russian vessel Akademic Ioffe. New ship-time has been committed by Brazil for another expedition in 2010-2011.
MAR-ECO enjoyed sharing experiences and results of its research explorations with the general public of all ages. The main portal was www.mar-eco.no [2] where a multitude of reports and resources were provided, including a deepwater interactive, popular reports and day-to-day accounts from several expeditions, backgrounders, videos from events, image galleries etc. In collaboration with the Bergen Museum, Norway, and a commercial sponsor Kongsberg Maritime ASA, MAR-ECO offered a travelling exhibition, Deeper than Light, that visited multiple venues in Europe and the USA. An in-depth popular well-illustrated book by professor Peter Boyle, Life in the Mid-Atlantic, provides a full account of the project from planning to completion. MAR-ECO collaborated with several artists fascinated by marine life, including a painter, a sculptor, and musicians. Animations and a computer game MARA for children were developed by associated media students. Two extended documentaries were produced by public TV networks in Norway and Portugal, and significant information and material were conveyed to a wide range of media outlets. For its efforts to communicate widely and originally, MAR-ECO won several awards, including the 2006 EU Descartes Price.
The book ‘Life in the Mid-Atlantic’ is a well-illustrated account of MAR-ECO:
background, processes, outcomes. Available on www.amazon.uk.com [3]
Visit the Mid-Atlantic Ridge Ecosystem Project [1] website to learn more.