Soft Sediments

With an area of over 400 million km2, deep-sea soft sediments arguably represent the most extensive habitat on earth. They are home to a plethora of species (the majority of which awaiting description), and play a key role in nutrient cycling, food production, detoxification and other ecosystem services of global significance. However, our biological knowledge of this habitat remains basic, with many fundamental questions still to be satisfactorily answered.

Our work in the Ocean Research and Conservation group aims to illuminate further details of this mysterious habitat. Current projects include the investigation of biodiversity / ecosystem functioning (BEF) relationships in deep-sea macrofauna, analysing the relative importance of abiotic and biotic factors in shaping communities (with relevance to the ‘Stability-Time Hypothesis’), gaining further knowledge of the major environmental variables determining the diversity, abundance, biomass and structure of soft-sediment communities, and the exploration of anthropogenic impacts on this apparently fragile habitat.

The research group also applies its scientific knowledge to the management of deep-sea fisheries, and is working with CEFAS (Lowestoft) and the Northwest Atlantic Fisheries Organisation to help shape protected areas in the Northwest Atlantic Ocean.

For more information see the personal pages of Oliver Ashford and Jesse van der Grient.

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Seamounts are submerged mountains, usually of volcanic origin. They are a significant feature of our oceans, with mountains over 1000 m in elevation covering ~17 million km2, and smaller features (knolls) covering >54 million km2 of the seafloor. These submerged mountains are frequently associated with a high abundance, biomass and diversity of organisms and may host a large number of endemic species. They appear to attract large concentrations of predators, including sharks, billfish, tuna, whales, seals and seabirds. Some deep-sea fish, such as orange roughy, form dense breeding aggregations around seamounts. On their surface, seamounts often host diverse communities of deep-sea corals which may form complex reef structures. 

However, the high biomass of predatory fish often associated with seamounts makes them particularly attractive to commercial fisheries. Many of the species targeted by the fisheries are long-lived (orange roughy may live for more than 150 years), whilst others aggregate for feeding or spawning, making them very vulnerable to overexploitation. Furthermore, the use of bottom trawls to access these fish stocks can be enormously destructive to the communities of animals living on the seabed, and these communities may take hundreds or even thousands of years to fully recover.

Our research on seamounts ranges from trying to gain a basic understanding of why they host such rich communities of animals, to mapping the extent and severity of fishing impacts on seamount ecosystems. This information is supplied to policy makers and fisheries managers in order to try and prevent future significant adverse impacts on these fascinating ecosystems.

For more information see the personal page of Dr Michelle Taylor.

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Hydrothermal vents

Deep-sea hydrothermal vents occur when cold seawater penetrates the ocean crust and comes into contact with hot rock below the surface. A complex chemical exchange occurs between the seawater and rock and the resulting fluid becomes buoyant, rushing upwards and exiting the seabed at up to 400oC. Hydrothermal fluid is enriched with chemicals, hydrogen sulphide being of the greatest biological significance. Specialised bacteria can use hydrogen sulphide as a fuel, and this forms the basis of unique chemosynthetic communities. These extreme environments are becoming the prime target of future mining operations in the deep ocean as the sediments and rock formations associated with vents are rich in copper, precious metals such as gold and silver and other valuable materials.

Past highlights of our work on hydrothermal vents include the discovery and characterisation of the first hydrothermal-vent endemic communities in the Southern Ocean,  discovery and description of a new species of yeti crab (the ‘Hoff crab’ – Kiwa tyleri), and description and in-depth investigation of the enigmatic ‘scaly-foot’ gastropod snail (Chrysomallon squamiferum).

For more information see the personal page of Dr Nicolai Roterman.

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