Science at the deep end
Interview: Dr Bhavani Narayanaswamy & Dr Robert Turnewitsch…
Science at the deep end
Interview: Dr Bhavani Narayanaswamy & Dr Robert Turnewitsch
The deep sea and its sea floor are now viewed as the largest and also the least explored ecosystem on Earth. This contrasts with the view – held as recently as only about 150 years ago – that there was no life at all more than 600 metres below the surface of the sea. Nowadays, as industry seeks to exploit marine resources (fish, hydrocarbons and minerals) at greater depths than ever before, scientists are accelerating their research to balance economic and environmental interests – as well as simply understand the mysteries of the Earth’s “inner space.”
The pressure on the deep is greater than ever, because of the rapid depletion of biological and mineral resources on land and in shallower waters. One of the challenges facing all deep-sea researchers, both in Scotland and elsewhere, is that “everyone and no-one is responsible” for what happens out in the depths of the ocean – certain aspects of human intervention affect large parts of the deep sea and in some cases the whole planet. “There are no boundaries in deep-sea research,” says deep-sea biologist Dr. Bhavani Narayanaswamy of the Scottish Association for Marine Science (SAMS). “A lot of the research we do has global implications, and good contacts and communication are vital to the future success of our science.” To tackle the challenges, Narayanaswamy and her colleagues at SAMS and other institutions in Scotland regularly work with other scientists from countries all over the world, sharing data, equipment and ship time to spread costs and help each other's research. But it is hard to achieve international agreement on how to control exploitation of deep sea resources.
The foundation for any advice on the control of the exploitation of deep sea resources is a sound ‘mechanistic’ understanding of how the deep sea ecosystem operates, including the physics, geology, chemistry and biology of the deep seas.
The deep sea is the “inner space” of the biologically active part of the Earth, but largely because of the relative remoteness and technological challenges, fundamental research is still only “scratching the surface.” A central challenge is to acquire an understanding of environmental variability across a vast range of time and space scales. Within this challenge, seafloor features of intermediate size deserve particular attention. Recent estimates by Paul Wessel and colleagues suggest there may be approximately 25 million abyssal hills, knolls and seamounts structuring the global seafloor.
Given this large number, the environmental influence of these topographic features is likely to be high. So far, however, there have only been very few systematic attempts to quantify how this influence manifests itself. One of Narayanaswamy’s colleagues at SAMS, Dr Robert Turnewitsch, is fascinated with how ocean currents interact with these seafloor features and influence the formation of sediments and how this controls submarine landscapes and implications for organisms living in and on the seafloor. “It’s important to understand how these hill- and seamount-controlled sediments are formed, as the underlying mechanisms will affect the distribution and nature of ecological ‘niches’ and therefore biodiversity,” says Turnewitsch. “Work has been going on for decades in the area of sediment dynamics, but not much attention has been paid to medium-scale sea floor topography.”
Turnewitsch studies the composition of the sediments and works with specialists in fluid dynamics and numerical modellers to analyse how sediments are formed. “The ocean flow has several components – for example, tidal and inertial ones – and some sedimentary deposits that were formed around submarine hills or seamounts may even help us to understand how certain aspects of deep-sea fluid dynamics may have varied in the past, and how this may have been interwoven with the overturning and mixing of the ocean and, therefore, climate change”.
A mechanistic understanding of the deep sea environment is inherently interdisciplinary. Narayanaswamy works with Turnewitsch on various related projects, looking at the underlying biology. “If we did our biological research in complete isolation, we would struggle to interpret what our results were telling us,” she explains. “For example, why is this animal living on only one side of a seamount? The answer may be more to do with ocean flow than any biological factor.” It’s all about “connectivity,” says Narayanaswamy, who is interested in learning more about why the same species seem to exist over very wide areas, and studying the very subtle differences between them from one place to another – much as Darwin and others discovered variations in species in different locations on land. “If we can understand the controls on biodiversity,” Narayanaswamy explains, “we can provide independent advice with regard to commercial activities, as well as with protection of the marine environment with the formation of Marine Protected Areas (MPAs). We need to protect these vulnerable habitats, but we also recognise the importance and benefit of the deep sea for society in general.”
The deep sea has a wide range of resources for fishing as well as oil and gas exploration, and there are also ambitious plans to harvest precious minerals and tap novel energy sources, at depths greater than 2,000 metres and beyond. For example, hydrothermal vents are being eyed as good potential sources for sulphide deposits, and the sea floor on seamounts could also be a valuable source of ferro-manganese crusts rich in metals of economic interest. Amongst the other major issues are climate change, acidification and pollution. Long-term man-made damage (fishing is the single biggest culprit) is easier to measure at a regional or local level and at shallower depths, and some habitats are affected more than others, but the impact on the fauna of the deep sea is largely unknown.
All these problems added together may have a major impact on the biodiversity of the deep sea, but international waters are not easy to police. “A lot of crucial science is being done in the deep sea,” says Narayanaswamy, but as quickly as the science progresses, so also does business see greater potential for profit and find better ways to exploit it. As a recent paper* explained: “One of the main problems that continue to cause concern is that the fastest movers in the deep sea are those who wish to use it as a service provider. Effective stewardship of deep sea resources will simultaneously require continued exploration, basic scientific research, monitoring and conservation measures.”
Scientists are, however, gradually adding to their knowledge of the world's most mysterious region, to balance the competing interests involved, at the same time as advancing fundamental research. The scientific community also plays a key role in the drawing up of policy, providing guidance and identifying areas which need legislative protection.
According to Turnewitsch, industry, scientists and conservationists have common needs in the form of a sound functional understanding of the environment; and these needs will have to be served by continuing to do more basic studies, including curiosity-driven research.
Curiosity-driven research also often results in practical uses, not just for environmental conservation but also for the benefits of businesses and industry. “For example, without curiosity-driven research, one would not know that manganese nodules existed and where to look for them”, Turnewitsch explains. “And only if we’ve gained a fundamental knowledge of how the deep sea works can we predict the effects of and guide any industrial-scale mining activities in the deep sea.” This knowledge is still “embryonic,” he adds, but any exploitation will have to take place “in parallel with our growing understanding of functional biodiversity,” and the “natural collaboration” between industry and scientists will help to protect the deep-sea environment over the long term, combined with greater public awareness and official attention.
Narayanaswamy agrees that fundamental research is not a threat to commercial ambitions. In fact, it has important implications that could help to minimise damage to the environment and provide independent advice for commercial activities in the deep sea. According to Narayanaswamy, industry and scientists should work closely together to ensure that good background sampling and analysis of an area is undertaken, ideally before any exploitation activities begin – for example, there are already plans to start mining in the deep sea near Papua New Guinea, and more research would help to minimise possible environmental impacts. Whatever deep sea research is undertaken, Narayanaswamy feels very strongly that improved standardisation is needed when it comes to the methods used to analyse what’s going on in the deep. For example, when environmental consultancies that are more often used to working in shallow-water environments offer their services to industry, they may not apply the same rules to their studies as deep sea researchers would.
Narayanaswamy explains this by describing how faunal samples are taken: “in shallow waters, you can use a 1mm sieve and find plenty of animals; in the deep sea, if you used a 1mm sieve, you would probably find very few, if any, animals, but if you used a finer mesh – say, 0.25mm – you'd get many more animals.”
Moreover, it is not just the size of the mesh used for sieves, but also the way researchers provide potential new species with names that are not always consistent. There are numerous organisations and scientists undertaking biological research, but many of them are not taxonomists, i.e. those that identify and name new species. In many laboratories, new species are given a code that differs compared to a code used by another institution for what is possibly the same species. The problem is, with declining numbers of taxonomists and a potential increase in the number of new species being found, how do you make sure that all species are given the same code until they are properly identified?
“We’re playing catch-up,” says Narayanaswamy, “and it all comes back to networks between different countries and organisations, as well as the community of scientists.” We also need more taxonomists to help with the classification of species, she adds. A scientist working in the north Atlantic may discover a “cosmopolitan” species which also lives in the Antarctic, but if the scientist is not familiar with the other region, how can we know it’s the same species and map the distribution of species?
Without standardisation, it becomes incredibly difficult to undertake comparisons between different studies and laboratories.
As Turnewitsch comments, what we know about the deep sea is “only a drop in the ocean.” Thanks to modern and evolving methods and technology, we are beginning to understand the functioning of the deep ocean, but the journey into “inner space” that started in the mid-19th century still has a long way to go – rising economic pressures making it more urgent than ever for the scientists to work more closely with industry, conservation organisations and policy makers to develop more effective and efficient ways to manage our deep sea resources and threats to deep sea biodiversity. This collaboration will have to be based on innovative and targeted fundamental research.
The role of MASTS
Narayanaswamy is the Principal Investigator in Deep Water Benthic Ecology at SAMS and also coordinator of the MASTS Deep Sea Forum. In her view, MASTS (the Marine Alliance for Science and Technology for Scotland) has stimulated deep sea research in a number of ways, encouraging collaboration and also improving access to funds. “Most of us had never sat down at the same table until last year,” Narayanaswamy explains. “This means we are now working as a group under the MASTS umbrella to develop new proposals for research.”
For example, MASTS researchers are trying to find funds for a new project in the northeast Atlantic to confirm the existence of a previously undiscovered cold seep – an area of sea bed which releases gas and other dissolved substances into the water, providing the conditions which allow many unusual species to feed and survive. This particular project will follow up on an initial discovery by Francis Neat and colleagues of Marine Scotland Science in 2011, when he collected rare clams in the northeast Atlantic that are normally only found in chemosynthetic environments – i.e., settings in which organisms do not fully rely on photosynthetically (plant-) produced food). The scientists don't know the exact location of the seep yet but, theoretically, seeps may occur every ~ 100km along the Atlantic margin. This is also a good example of a multi-disciplinary initiative, says Narayanaswamy, which will add to our knowledge of these unusual habitats.
Turnewitsch says that MASTS “facilitates and formalises interconnections between people,” as well as makes it easier to fund new research. On the opposite side of the world, he is currently doing research on samples from the Tonga Trench in the western Pacific, the second-deepest point in the ocean at almost 11,000 metres. “Because of technological challenges, we still only know very little about these so-called ‘hadal’ trenches,” says Turnewitsch, “so any sample we can get makes a huge difference.” MASTS helped to fund the shipping of special equipment to the Tonga Trench which made this work possible, and will do the same for the project in the northeast Atlantic.
The ‘seed’ funding provided by MASTS facilitates proof-of-concept and other smaller studies and results in research output that can then be used to bid for funding for large projects.
MASTS researchers have access to a variety of state-of-the-art equipment, some of which has been specifically designed by MASTS researchers. Examples are the ultra-deep free-falling benthic lander systems designed by Dr. Alan Jamieson (OceanLab) to operate and sample in the deepest parts of the world's oceans. The challenge of conducting research in these extreme environments means that much of the science is, by definition, cutting edge. Use of modern technology, together with practical ingenuity is leading to novel discoveries including species and ecosystems new to science.
According to Narayanaswamy, the forum over the next couple of years will hope to focus more on the following issues:
- Undertake research into cold-seep connectivity in the northeast Atlantic.
- Intermediate-scale sea floor features (hills, knolls, seamounts, canyons, fracture-zone valleys and hadal trenches) are a major research theme because so little is known about their effects on biology, biogeochemistry, physical oceanography and interpretation of sedimentary palaeorecords of past environmental change.
- Map and describe areas of suspected vulnerable marine ecosystems (VMEs). A total ban on deep-water trawling would not be universally welcomed, but there is widespread agreement that when VMEs are discovered, they should be closed to fishing. Habitat-suitability models are still not well enough defined to be of use to management, so more research is needed – whatever the cost.
- Ocean acidification – are we going to see major shifts in the vertical zonation of the deep sea as the saturation state horizon shifts? How will we measure this? How will this interact with rising temperatures and spreading zones of low and decreasing concentrations of dissolved oxygen?
- “Standardisation” – collecting, processing and identifying new species, according to internationally agreed parameters. “If this isn’t tackled,” says Narayanaswamy, “there is no chance of doing any monitoring work anywhere.”
The deep sea forum
Scotland has a vast deep sea area stretching out to the 200 nautical mile boundary, encompassing a range of diverse habitats as well as key economic resources such as fishing, oil and gas. In addition to scientific interest in the deep sea, policy makers are required to protect many of these poorly-understood habitats and the often fragile ecology and biodiversity that they support. Increasing access to deep sea habitats and exposure through various media has also stimulated significant public curiosity in the life found in these deep, cold, dark environments.
The MASTS deep sea forum was set up in 2012 with the following aims:
- Interact with the different communities with an interest in the deep sea
- Engage with new partners and promote collaboration across disciplines in order to further deep water research both at a national level as well as internationally
- Ensure greater integration between researchers investigating deep/shallow water and the climate/atmosphere
- Discuss and help deliver the best scientific knowledge available to policy makers
The scientists in the deep sea forum believe that a more holistic approach to studying the deep sea is needed, bringing together researchers from a wide range of disciplines, including ecologists, chemists, physicists, modellers and climate scientists. They also need advanced technology that can operate remotely under extreme conditions.
Did you know?
- The oceans cover 71% of the planet’s surface (the sea floor covers 362 million square kilometres out of a total of 510 million square kilometres), with 50% of the water below 3,000 metres in depth and a mean depth of 3,800 metres.
- The deepest ocean trenches are more than 10,000km deep, further down below the surface of the sea than the highest mountain ranges are above sea level – e.g., Mount Everest would fit inside the Marianas Trench in the western Pacific with a couple of kilometres to spare.
- Only 5% of the deep sea floor has been explored and less than 0.01% of the deep sea floor (the equivalent of a few football fields) has been studied in detail.
- The volume of the deep sea (or “pelagic” zone) is over one billion cubic kilometres.
- Over 60% of the sea floor has less than 200 metres of sediment cover. In some regions, sediment cover amounts to several kilometres.
- The Earth's crust in the deep sea is rarely more than 7km thick and hydrothermal vents on the sea floor, where water seeps into the ocean, can generate temperatures of more than 400 degrees Centigrade.
- The Ocean Biogeographic Information System contained over 19.4 million records as of September 2009, but only 75,532 of these were from depths of more than 1,000 metres, or approximately 0.004% of the total.