New deep-sea coral garden discovery in west Greenland

Chris Yesson

by Stephen Long, Chris Yesson & Bridget Sparrow-Scinocca

Coral garden with grenadier fish Anemone field in Greenland
Coral and sponge garden 550m, deep-sea benthic video sled image West Greenland Benthos - Holothurian

Deep-seas are the largest ecosystem on Earth covering 65% of the planet. Often defined as waters deeper than 200m, sunlight is unable to penetrate and so this is a world that exists in near total darkness. Out of sight and out of mind, we know relatively little about these deep-sea habitats. In fact, we have more detailed maps of the surface of Mars than we do of the deep seafloor on Earth.

Despite our lack of knowledge, deep-seas are increasingly of economic importance, supporting commercial fisheries and offering potentially lucrative mining opportunities. Greenland provides a great example. The country’s 2.2 million km² of waters, support deep-sea fisheries for prawns and halibut, which provide over 80% of the country’s export income. However, to date the vast majority of Greenland’s deep-sea remains unexplored.

Working with scientists at the Greenland Institute of Natural Resources, we have developed a low-cost, innovative video sled, which has allowed us to see these deep-sea habitats for the first time. Typically, deep-sea exploration is a difficult and expensive business. A major reason is that pressure increases by one atmosphere for every 10m of descent, so at 500m the pressure is some 50 times greater than at the surface. By combining lights, lasers and a GoPro video camera in special pressure housings, the video sled allows us to access the deep-sea on a budget.

Deep-sea camera sled
Deep-sea camera sled being deployed from GINR research vessel Paamiut

Starting in 2017, we have been towing the video sled behind research vessels, to build up a picture of the nature and distribution of deep-sea habitats in west Greenland. The images from one area, on the edge of the Toqqusaq Bank, at depths between 300 and 600m, grabbed our attention.

Coral and sponge garden 550m, deep-sea benthic video sled image
Coral and sponge garden at 550m

The next step was to painstakingly review over 1,200 images extracted from the videos. This work was carried out by Bridget Sparrow-Scinocca, an MSc student at ZSL Institute of Zoology, who individually annotated over 44,000 animals in the images.What the images showed was a soft coral garden. This delicate and diverse habitat features abundant cauliflower corals as well as feather stars, sponges, anemones, brittle stars, hydrozoans, bryozoans, fish and other organisms.However, the slow growth, long-life and delicate physical structure of corals and sponges in this coral garden mean it is sensitive to physical disturbance. Our new research proposes that this coral garden is recognised as a vulnerable marine ecosystem (VME), covering some 486 km², about 90,000 football fields. The term VME was introduced by the UN to recognise deep-sea habitats that were both ecologically importance and vulnerable to human impact.

This soft coral garden proposed VME is immediately adjacent to areas where the seafloor is trawled for commercially important cod, halibut and prawns. We are currently working with the fishing industry and government in Greenland to share our new research and ensure this habitat is protected. So far we have had a really positive response. This is great news as the sustainable management of deep-sea resources is vital for healthy ecosystems and economies in Greenland and beyond.

You can read the study describing this coral garden, here.

Find out more about our research in Greenland, here.

…And even play Tricky Trawling - an online game about sustainable fishing in Greenland.

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