UNPRECEDENTED changes will cause a famine in the deep ocean floor as Earth's largest habitat is crippled by climate change, research suggests.

An international study suggests food supplies for seafloor ecosystems will decline by 50 per cent and and the impact will have a significant impact on the planet.

Dr Andrew Sweetman, of the Lyell Centre for Earth and Marine Science and Technology at Heriot-Watt University in Edinburgh, said: "The rate of change underway in our oceans is faster than at any point we know of in geological history.

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“Deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. We should all be concerned at what’s happening on our ocean floors."

Sweetman worked with experts from 20 other oceanographic research centres to predict the changes set to hit the deep ocean floor from the Arctic to Atlantic oceans by 2100.

They focused on areas between 200m-6,000m down, looking at increased seabed temperatures, falling oxygen levels and increasingly acidic water.

The results are published on open-access journal Elementa and Sweetman said: "The organic matter cycling that occurs in the deep sea helps to buffer the ocean against pH changes and the effects of ocean acidification.

Abyssal ocean environments, which are over 3000m deep, are some of the most food-deprived regions on the planet.

“These habitats currently rely on less carbon per m2 each year than is present in a single sugar cube.

“We’ve shown that large areas of the abyss will have this tiny amount of food halved by 2100.

“For a habitat that covers half the earth, the impacts of this will be enormous.”

Temperatures are also expected to rise by 1C within 85 years, affecting the metabolism of animals and triggering the need for more food as supplies dwindle. The Pacific, Atlantic and Indian oceans are expected to be hardest hit.

The increasing practice of deep sea fishing is also predicted to have a major impact on the at-risk ecosystems, as is the release of pollutants. Sweetman said: "Pressure from fishing has led to many deep-sea fish species being severely exploited through trawling and longlining, with some species having been fished to commercial extinction.

“There is also extensive interest in mineral mining at hydrothermal vent systems along mid ocean ridges, at seamounts and polymetallic nodule areas at abyssal depths, such as the Clarion Clipperton Zone of the Pacific Ocean.”

Co-author Dr Lisa Levin, of America's Scripps Institution of Oceanography, said: “Because many deep-sea environments are naturally very stable in terms of environmental conditions, even slight changes in temperature, oxygen, food supply, and pH are likely to significantly lower the resilience of deep-sea communities to the impact of human activity.

“These many challenges call for intensified observations of and spatial planning for the deep ocean, coordinated at an international level.”

Professor John Underhill, chief scientist at Heriot-Watt, said: “Andrew and his colleagues’ research has produced a timely reminder of the impacts of the world’s changing climate on ecosystems living on the ocean floor.

“Their work showcases the quality, depth and breadth of research being undertaken into understanding the deep oceans at Heriot-Watt in the Lyell Centre for Earth and Marine Science & Technology.”