The Lophelia reefs of the Minch

Date: October 14, 2005

Records of Lophelia pertusa from inshore UK waters go back to Victorian times when this deep sea coral was described in fishermen’s reports. In the 1900s a fine specimen reached Glasgow University’s Hunterian Museum from a long-line fisherman operating in the Minch and the Sea of the Hebrides to the west of Scotland. In the late 1960s a dredger turned up dead coral east of Mingulay, and John Wilson saw Lophelia colonies on a seabed ridge during pioneering manned submersible dives in 1970. In 1999 David Long, of the British Geological Survey (BGS), and Murray Roberts, of the Scottish Association for Marine Science (SAMS) began to wonder whether there were still live Lophelia reefs in the Minch.

The first hint that this might indeed be the case, came during a research cruise in 2001, when the Royal Research Ship Discovery was sheltering from autumn gales in the Minch, unable to do planned work. The captain was persuaded to sample the seabed in the calmer waters east of Mingulay, where dead coral rubble, a fragment of live Lophelia, and a diverse animal community were discovered. Echosounder results showed a pattern intriguingly like a reef area. It was not until summer 2003 that a closer look could be taken. The Mapping Inshore Coral Habitats (MINCH) project began in June 2003 aboard the Research Vessel Lough Foyle, The first survey clearly showed the seabed ridge John Wilson described in 1970. Next to this were a series of hummocks. They looked like Norwegian Lophelia reefs, and were a top priority for the camera work. SAMS scientist, Dr. Murray Roberts, onboard the Lough Foyle, described the first images from the reef: “Excitement grew on board as the cameras were lowered. The ship drifted across the survey area and the seabed habitats changed from soft, burrowed sediments, to areas with fireworks sea anemones and small stones colonised by colourful crinoids (feather stars), then we saw larger rocks, some with fan-shaped sponges. A little while later, coral rubble came into view – it became denser and soon included scattered live coral colonies. Shortly afterwards the cameras flew across large white coral heads. We had found it, there was a live Lophelia reef in the Sea of the Hebrides, just as the early reports and fisherman’s observations had suggested.” In May 2005, after a two-year wait, SAMS scientists once again returned to the Sea of Hebrides, this time aboard the Greenpeace ship Esperanza and armed with equipment ranging from remotely operated vehicles (ROVs) to simple mechanical grab samplers. The scientific team was joined by John Wilson, an expert on Lophelia reefs, who visited the same area over 30 years ago aboard the manned submersible Pisces. The objective of the expedition was to collect images of the reef and to collect live specimens for laboratory experiments to improve our understanding of these little- studied corals. “Most of my work is based on laboratory experiments on live Lophelia“, explained SAMS scientist, Lyndsey Dodds. “So I am dependent on samples collected throughout the year. The trip with Greenpeace on the Esperanza represented a great opportunity to obtain samples from a large ship with the use of specialised equipment.” The Sea of Hebrides flows between the Outer Hebrides and the Scottish mainland and is often subject to strong winds and large swells, which develop in the northeast Atlantic. Fortunately the first full day at the site was blessed with good weather. After a few initial technical problems with the ROV, a video grab sampler was readied. The grab sampler provides an accurate tool for collecting small samples of coral from the reef. Operating it is a delicate procedure that involves deploying metres of cable (in this case 150 metres) to reach the bottom. The ship’s Captain then uses a special system developed by SAMS that shows the location of the ship in relation to the reef mounds, in order to keep the ship over the reef. There was mounting excitement onboard as crew members and scientists alike watched video screens located throughout the ship and efforts to make a successful grab. “Soon some white patches appeared in the distance, and we waited impatiently until they came into focus”, recalls Dr. Andrew Davies, one of the SAMS scientists who was onboard for the expedition. “Sure enough, they were what exactly what we had been hoping to find – pristine white heads of live Lophelia attached to large banks of dead coral framework.” Scientists now believe these reefs may be up to 4000 years old. When the first successful grab broke the surface and the crew pulled it back onboard, a curious crowd gathered within seconds and was instantly rewarded with the rare sight of glistening samples of the cold-water coral, Lophelia pertusa. Work continued for 10 days and nights, with teams working around the clock collecting data, deploying video systems and retrieving samples. Apart from a single bout of strong winds, the camera systems and grabs were deployed almost 50 times, collecting a wealth of information, videos and samples. “There were a total of eight grabs that resulted in live coral collection,” Lyndsey Dodds remembers. “Back at the laboratory, I am using these samples to understand more about the basic biology of this species. This will then allow informed predictions of how this animal may react to changes in its environment.” Cold-water corals such as Lophelia pertusa intrigue the scientists that study them. They may be many thousands of years old, and may contain high resolution records of long-term climate change. It is possible that they may be significant carbon sinks in temperate waters and important biodiversity hotspots in the deep sea. Numerous studies from around the world have shown the damage that can be caused to cold-water coral reefs by bottom trawling. The video collected from the Minch reefs showed the three dimensional reefs to be in good health: the small areas visited showed no obvious signs of fishing-related damage. Every expedition to cold-water coral reefs answers some questions and gives rise to many others. So little is known about life in the depths of our oceans and new discoveries are being made all the time. It is only recently that scientists have begun to develop the technology needed to explore life in such challenging conditions. Unfortunately, damage from deep-sea trawl fishing vessels is evident on many of these fragile and ancient coral ecosystems before they have been adequately studied. The danger is that some species or reefs may be destroyed or significantly damaged before they have even been discovered. A moratorium on bottom trawling would preserve reefs like this in the high seas for many generations to come. Dr. Davies, Dr. Roberts and other scientists at SAMS are among over 1,400 scientists who have signed on to a scientists’ statement (1) calling for an interim suspension to bottom trawling in international waters, until legally-binding regimes for the effective conservation and management of fisheries and the protection of biodiversity on the high seas can be developed, implemented and enforced by the global community. Current coral research at SAMS Lyndsey Dodds describes her research at SAMS: “Respiration rate is an indicator of metabolic activity and ‘health’ of an animal. I have investigated the baseline rate of respiration for Lophelia and how this is affected by temperature changes and changing oxygen levels, reflecting conditions that may be experienced in their natural environment. I am also interested in the prey items of Lophelia and will be carrying out live feeding experiments with the Esperanza samples. This work is supported by lipid analysis on the tissue of Lophelia. A portion of the Lophelia samples that were collected on the Esperanza were frozen for this analysis. By analysing the lipids in the tissues of an animal it is possible to get an indication of the different food sources on which it feeds.”

Notes: (1) Marine scientists’ statement. For more information: Visit the SAMS’ website Contact SAMS

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