Science in Support of Protecting High Seas Marine Habitat and Communities

Deepwater Fauna of the Continental Slopes and Canyons in Atlantic Canada

Most fisheries and marine research has focused on continental shelves. While there has also been extensive study of the midwater zone of the deep oceans, the ecosystems of the continental margins—between the shelves and the ocean basins—remain poorly known. The expansion of fishing and other human activities into greater depths in those marginal areas has recently drawn international attention, including a resolution A/RES/61/105 adopted by the U.N. General Assembly in March 2007 to protect vulnerable marine ecosystems, including cold water corals, from destructive fishing practices. Regionally, in September 2007, the Northwest Atlantic Fisheries Organization (NAFO) closed an area around the southwest Grand Banks (NAFO Division 3O) for five years during which time research will be conducted to support strategies for protection of deepwater corals living on the continental slope. Canada had previously closed two coral areas off Nova Scotia, in addition to declaring a Marine Protected Area (MPA) covering the Gully, a very large submarine canyon immediately east of Sable Island. Canadian scientists have played leading roles in providing technical advice to both the U.N. and NAFO decision-makers.

In 2007, scientists from Fisheries and Oceans Canada (DFO) at the Bedford Institute of Oceanography, DFO Newfoundland (Northwest Atlantic Fisheries Centre) and Memorial University formed a team to explore the fauna in the deep waters in selected areas of Canada’s continental slopes. The 2007 field program (July 7-29) involved deployment of a deepwater submersible (ROPOS) from CCGS Hudson in four areas of operation: the Gully MPA, the Stone Fence Lophelia Conservation Area (NAFO Division 4Vs), on the southwest Grand Banks at Haddock Channel, and Desbarres Canyon (NAFO Division 3O). More than 3,000 high resolution digital images, 10,000 high quality frame grabs and many hours of high resolution colour video coupled with remotely operated vehicle (ROV) positional data were obtained. Previous observations were limited to depths less than 500 metres, but with the ROV scientists obtained data to depths of 2,500 metres at both the Gully and Stone Fence and to 1,000 metres on the SW Grand Banks.

Early results from this mission include the discovery of 10 coral species previously unknown to Canadian waters, including a second species of the large fan-shaped, habitat-forming bubblegum coral (Paragorgia johnsoni). Mapping the distribution of coral is the first step towards their conservation and associated research into coral genetics, longevity and the ecology of deep-water faunal communities in general, which will be gained from this program, will enable science-based decisions for the long-term protection of these vulnerable marine habitats.

The bubblegum coral Paragorgia arborea can reach meters in height and hundreds of years in age. The upright nature of this species makes it vulnerable to bottom-tending mobile fishing gears.

A second species of bubblegum coral, Paragorgia johnsoni, is a new Canadian record established from the 2007 field program. Here it is shown with brittlestars entwined in its branches.

Several coral species are attached to bedrock on the southeast slope of Banquereau. From left to right: a solitary cup coral (Desmophyllum sp.), a mushroom coral (Anthomastus sp.), Anthothelia grandiflora (purple).

Understanding Ocean Variability and Marine Ecosystems

In the water column there are concentrations of small migratory fish and crustaceans, notably the myctophid lanternfishes, which feed at night in surface waters and spend their days at several hundred metres depth, thereby carrying food energy downwards. An array of small predators awaits them at depth, while larger animals hunt the predators. Among the latter are endangered bottlenose and sperm whales, which feed on squids a kilometer below the surface. There are also commercially exploited species such as turbot and swordfish—the latter a specialized deepwater predator. Meanwhile, the presence of the seabed and especially of canyon features accelerates water flows while anchoring filter-feeding organisms (including corals) that exploit the passing food. To effectively protect the continental-slope ecosystems and conserve the resources there, it is necessary to understand the full range of biodiversity and the ecological links amongst the various species.

In 2007, a two-part field program collected data on the fauna of the continental slope in the Gully MPA in NAFO Division 4Vs. Data were collected from depths to 2,500 metres, where previous studies had only reached 500 metres. A complementary survey of the midwater fauna in the Gully MPA was funded through DFO Maritimes Region, Oceans and Science branches. This was the first survey of life in the mesopelagic and bathypelagic zones of Canadian waters in twenty years. It was one of the first globally to fish at such depths within a canyon, the Gully (the largest submarine canyon along the eastern seaboard of North America) being big enough that a midwater trawl can be worked at depth within the feature. Both surveys have documented new species records for Canadian waters, some of which may prove to be species wholly new to science. It is further expected that, once analyzed, the data collected will support initial models of the functioning of continental slope and canyon ecosystems, while providing a solid foundation for the design of the next generation of studies. Both surveys were cooperative ventures, involving university and other experts, some from outside Canada, while the midwater survey was designed to be comparable with ongoing U.S. research on Bear Seamount and along the edge of Georges Bank. Expanding knowledge of biodiversity within the ecosystem through study of lesser-known, non-commercial species, including species lower on the food chain, is recognized as a key activity that is part of Canada’s International Fishing and Oceans Governance plan.

A Fang-tooth or Ogrefish captured during the 2007 survey of the mesopelagic zone of the Gully Marine Protected Area (NAFO Division 4Vs). This is a carnivorous species feeding on crustaceans as a juvenile and fish as an adult.

Viper Fish. This is a mesopelagic species which is believed to migrate to near-surface waters at night.