Deep-Water Ecosystems

Although there have been 150-years of deep-sea exploration the vast majority of the global ocean remains an unknown. New ecosystems and deep-sea habitats continue to be regularly discovered. The exotic lifestyles and strange creatures of hydrothermal vents were seen for the first time in 1977. The related faunas of cold seep systems were only encountered in 1984. These discoveries were made possible by direct observation of the seafloor through the use of manned submersibles and deep-diving remotely operated vehicles (ROVs).
NOCS deep-diving (6,000m) ROV Isis.
Other creatures, such as deep-sea corals, have been known for well over 100-years, but it is only in recent decades that the true nature of their ecosystems and habitats has been revealed. Again new technologies have been very important in the discovery and mapping of these new habitat types. The development of deep-sea sidescan sonar imaging, swath bathymetry mapping, and 3-D seismic surveys is starting to give us a broad view of the deep-sea landscape for the first time.
The deep-sea coral coral Lophelia pertusa as illustrated in Charles Wyville Thomson's 'The Depths of the sea' (1873).
The National Oceanography Centre, Southampton (NOCS) has a long history of deep-water technology development and its application in the discovery and study of deepwater ecosystems. We have a near-unrivalled experience in both long-term and large-scale investigations of deep-water ecosystems. These studies have ever increasing relevance to Political, Commercial and Societal concerns for the global ocean.

Following an extreme winter in 1995/96, the seafloor grazing rate by seacucumbers increased by over an order of magnitude on the Porcupine Abyssal Plain (4,850m). This change in ecosystem function was driven by a sudden bloom in the population of a small sea cucumber called Amperima rosea. Our long-term (20+ years) studies in the deep (5,000m) NE Atlantic have revealed extraordinary changes in this ecosystem and its functioning on the deep-ocean floor that may be linked to climate change. We have carried out ultra-large-scale integrated surveys of the UK’s deep-water territory, in partnership with both the oil industry and the UK Government, that have provided the database necessary for ecosystem / habitat-based management of deep-water resources. One key discovery of the UK surveys was a field of coral topped sand volcanoes at 1,000m water depth in the Rockall Trough, now known as the ‘Darwin Mounds’. These features were located and identified through the joint use of NOCS’ deep-tow side-scan sonar system TOBI and seafloor camera survey vehicle WASP. Our subsequent surveys indicated that these coral growths were being damaged by deep-water trawlers targeting fish such as the Roundnose Grenadier (sometimes sold as ‘Hoki’) and the Orange Roughy.
Commercially trawled deep-sea fish: roundnose grenadier (above) and orange roughy (below).
On 22 March 2004, European Union Fisheries Ministers finally agreed to give permanent protection to these unique deep-water corals, recognising the Darwin Mounds as an important habitat and creating the UK’s first deep-sea marine protected area.

While deep-sea coral, hydrothermal vent and cold seep communities are probably best known to the general public, the deep sea is home to an extraordinary diversity of marine life – most of which is still completely unknown.
First discovered by NOCS scientists in 1998, the coral ecosystems of the 'Darwin Mounds' are now protected by European Union legislation and have become the UK's first deep-sea Marine Protected Area.
Although the dominant (55%) environment on our planet is the abyss (2,000-6,000m water depth), almost twice the size of all land surfaces combined, only a very tiny proportion of that area has been explored in sufficient detail to records it species, habitats and ecosystems. With the average point on our planet covered more than 2-miles deep in water, every deep-sea exploration is practically guaranteed to reveal something new!