J. Murray Roberts Discusses Cold-Water Coral Ecosystems
Fast Moving Front Commentary, September 2010
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Article: Reefs of the deep: The biology and geology of cold-water coral ecosystems
Authors: Roberts, JM;Wheeler, AJ;Freiwald,
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J. Murray Roberts talks with ScienceWatch.com and answers a few questions about this month's Fast Moving Fronts paper in the field of Geosciences.
Why do you think your paper is highly
cited?
This was the first paper that tried to draw together biological and geological work on cold-water coral ecosystems. From the mid-1990s work on the cold-water corals of the deep ocean has increased exponentially. There have been dramatic discoveries of deep-sea coral reefs and giant coral carbonate mounds.
In our paper we tried to review this information and summarize exciting new work on environmental records of ocean climate locked away in the skeletal remains of these corals. We also noted that in many places cold-water coral habitats have been badly damaged by bottom trawling and that they are currently threatened by ocean acidification.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
PHOTO 1:
"J Murray Roberts prepares a
microlander..."
PHOTO 2:
"Johnson-Sea-Link submersible..."
PHOTO 3:
"Cold-water coral..."
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It's very much a synthesis of knowledge, but in making this synthesis, we tried to set the work in a wider context and put forward a conceptual model of how cold-water coral reefs and coral carbonate mounds develop over time. The year before our paper was published work on the predicted change in ocean carbonate chemistry came to the fore.
A particularly relevant paper appeared in Nature showing that the depths at which hard corals can produce their skeletons was likely to shallow in the present century (Orr et al., Nature 437: 681-686, 2005). The following year, John Guinotte and colleagues overlaid this predicted shallowing in the aragonite saturation horizon with the present-day distribution of cold-water corals to show that many of the cold-water coral habitats we've just discovered may soon be growing in corrosive seawater (Guinotte et al., Frontiers in Ecology & the Environment 4: 141-146, 2006).
Over the last four years, research into "ocean acidification" has taken off with research programs established in Europe, UK, and USA.
Would you summarize the significance of your paper
in layman's terms?
Our paper reviews the hidden world of cold-water corals. There are more species of coral in the deep sea than on shallow tropical coral reefs. Cold-water coral habitats are global—they are found from the deep water tropics north to the Arctic Circle and south to the Antarctic. Beyond that, they are incredibly long-lived with individual cold-water corals now known to live over 4,000 years while the structures they form can trace their origins back over two million years.
The corals form complex habitats home to a rich biodiversity of other species. Some of these species, like deep-sea sponges, are storehouses of biochemicals, and recent research has shown these can be potent drugs with anti-cancer properties. Cold-water coral habitats also often contain species unknown to science.
Sadly, just as we begin to understand cold-water corals we see they have been damaged by deep-sea bottom trawling and are threatened by the gradual warming and acidification of the seas we are now witnessing. To help explain these issues we have developed a website devoted to cold-water corals.
How did you become involved in this research, and how would you describe the particular challenges, setbacks, and successes that you've encountered along the way?
I started working on cold-water corals in 1997 as a postdoc with the late John Gage, a professor of deep-sea biology at the Scottish Association for Marine Science. The project was great, but relied heavily on in-kind support from oil companies to get to sea. In the late 1990s there was an oil price slump and this support melted away. Although stressful at the time, the need to form collaborations and get to sea was great training. Getting to cold-water coral habitats and studying them over time remain the greatest challenges.
Answering even the simplest questions—What do the corals eat? Do they spawn? How fast do they grow?—requires offshore research vessels and equipment capable of sampling within delicate coral habitats sometimes over a kilometer beneath the waves. Over the last 13 years I've been lucky enough to use a variety of marine technologies from mapping acoustics to discover the Mingulay Reef Complex off Scotland to remotely operated vehicles and manned submersibles to explore and sample the habitats.
My group has used a variety of seabed landers that can be left amongst the corals for up to a year equipped with cameras and sensors and we then use this local environmental data to help us study live corals brought back to the laboratory. We need this basic understanding of coral ecophysiology and the natural variability of their environments if we are going to understand their sensitivity to future change.
Where do you see your research leading in the
future?
A major current focus of my research into cold-water corals is to enlarge the scale that we consider their ecology and palaeoceanographic archives to span ocean basins. The findings we reviewed in our 2006 paper were based upon almost a decade of individual studies examining separate cold-water coral reefs or clusters of coral carbonate mounds.
European projects have begun to bring the community together at a wider scale, but even today our understanding of biogeography and connectivity between cold-water coral habitats remains very poor. Without understanding gene flow between habitats our ability to design ecologically meaningful Marine Protected Areas remains very limited.
"This was the first paper that tried to draw together biological and geological work on cold-water coral ecosystems."
Similarly, we will only start to understand the rich biodiversity of these habitats if we sample them in a standardized manner and make the best use of specialist taxonomists who can identify the animals and describe the new species. We will also only really unlock the palaeoceanographic archives in the coral skeletons if we can sample them across ocean basins following the history of the intermediate and deep water masses that are so important to global climate.
Work at ocean basin scale requires international collaboration and this sets up a whole new set of challenges and opportunities. The Trans-Atlantic Coral Ecosystem Study which I initiated in 2008 has led to a European Science Foundation program and the TRACES community are working hard on developing this approach in the Atlantic and further afield.
Do you foresee any social or political
implications for your research?
One might assume that deep-sea biodiversity and habitats are remote from people's daily experience and of little social or political interest. But in fact this has proved far from the case. There has been an international outcry against the damage deep-sea trawlers cause to deep-water habitats, particularly on the High Seas remote from national jurisdictions.
In late 2006 these concerns reached the level of the United Nations General Assembly who published resolution 61/105 calling upon states to protect vulnerable marine ecosystems including cold-water corals. The beauty and diversity of pristine cold-water coral habitats contrasted with those damaged by trawling has brought home the unsustainable nature of deep-sea fisheries and helped provide the impetus for international conservation actions like the Deep Sea Conservation Coalition.
The vulnerability of cold-water corals to ocean acidification is now
subject of active research around the world and in years to come we may see
great efforts to understand the biotechnological potential of cold-water
coral habitats. For these reasons, and simply because no generation has the
right to destroy biological diversity, cold-water corals are and will
remain a deep-sea research and conservation priority.
Dr. J. Murray Roberts
Reader in Biodiversity
Centre for Marine Biodiversity & Biotechnology
School of Life Sciences
Heriot-Watt University
Edinburgh, Scotland
KEYWORDS: NORTHEAST ATLANTIC; LOPHELIA-PERTUSA; SEA CORALS; ROCKALL TROUGH; NE ATLANTIC; MOUNDS; OCEAN; SCLERACTINIA; VENTILATION; IMPACTS.
Photo 1:
J Murray Roberts prepares a microlander to be deployed amongst cold-water corals off the coast of Florida. Image courtesy of Art Howard.
Photo 2:
The Johnson-Sea-Link submersible bringing the microlander back to the surface. Image courtesy of Liz Baird.
Photo 3:
A colony of the cold-water coral Lophelia pertusa from the Mingulay Reef Complex west of Scotland. Lophelia pertusa is the most widespread reef framework-forming cold-water coral producing elaborate deep-sea coral reefs and coral carbonate mounds. Image courtesy of JM Roberts.