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Blue-sea thinking: Technology is transforming the relationship between people and the oceans

Humans are starting to use the sea more as farmers than as hunters, says Hal Hodson

IN THE summer of 1942, as America’s Pacific fleet was slugging it out at the battle of Midway, the USS Jasper, a coastal patrol boat, was floating 130 nautical miles (240km) off the west coast of Mexico, listening to the sea below. It was alive with sound: “Some fish grunt, others whistle or sing, and some just grind their teeth,” reads the ship’s log.

The Jasper did not just listen. She sang her own song to the sea—a song of sonar. Experimental equipment on board beamed chirrups of sound into the depths and listened for their return. When they came back, they gave those on board a shock. The Jasper‘s charts said she was in 3,600 metres (2,000 fathoms) of water. But the time it took the soundwaves to bounce back said the bottom of the ocean was just 450 metres below the ship’s hull.

The instruments were not wrong. The interpretation was. The Jasper’s crew had found a new ecosystem so dense with aquatic life it appeared to their rudimentary sonar to be solid—a “phantom bottom” to the ocean. Unlike the sea’s true floor, it moved, its billions of inhabitants rising en masse to feed at night, then sinking away from predators during the day. This “deep scattering layer”—named for the way it was found by the scattering of sound waves—is not local to Mexico. Present in all the oceans, it is one of the largest ecosystems in the world. Its daily rise and fall is their heartbeat, an unseen spectacle of planetary extent.

That such a mass of animals should go undiscovered for so long shows quite how inscrutable the sea has always been. The subsurface ocean is inhospitable to humans and their machines. Salt water corrodes exposed mechanisms and absorbs both visible light and radio waves—thus ruling out radar and long-distance communication. The lack of breathable oxygen severely curtails human visits. The brutal pressure makes its depths hard to access at all.

The discovery of the deep scattering layer was a landmark in the use of technology to get around these problems. It was also a by-blow. The Jasper was not out there looking for deepwater plankton; it was working out how to use sonar (which stands for Sound Navigation And Ranging) to spot submarines, and thus help to keep ships like those at Midway safe.

Sonar research has been mostly military ever since, as have various other forms of high-tech ocean sensing. But the new sensorium allowed an exploration of the ocean’s depths that became crucial to science and commerce. Sea-floor surveys undertaken in the 1950s and 1960s discovered a chain of underwater mountains snaking through the oceans like the seam on a baseball. This discovery helped transform the controversial notion of continental drift into the far more powerful and explanatory theory of plate tectonics. Modern industrial fishing and offshore oil and gas benefited in similar ways: seeing the seas and their contents mattered.

In the past decade, remote underwater observation has moved to a new level as sonar technology has become more advanced. Computers have become powerful enough to turn the apparent gibberish that is created by numerous sound sources at various frequencies into high-resolution “sound pictures” of underwater objects. And smaller, cheaper electronic components using less power—a gift from the smartphone boom which kickstarted progress in drones, robotics and small satellites—are now putting to sea. They may be just as transformative there as in the skies and in space.

Darling it’s better down where it’s wetter

All this change promises to bring about a transformation in the way humans interact with the oceans. For most of history, people have had a hunter-gatherer relationship with the seas. That approach no longer works. If overfishing continues at the current rate, the seas will run out of fish. One response to this would be to decry the technological change that has made such overfishing possible. Another is to ask how the latest technology can be used in ways that improve things, undoing the damage of the past and making the old hunting ground a new realm, one that is more productive and more sustainable.

One crucial change brought about by the new technology is a reduction in the number of people involved. Until recently, using sonar was an expensive business, requiring a ship with a crew, towing equipment through the depths behind it. Now underwater drones (such as the one being launched in the picture on the previous page) can move around as fast as ocean currents flow, which means they can go wherever they want and stay there if needed. They can communicate acoustically, with each other or with a mother ship. Their lithium-ion batteries—one of those technologies smartphones have greatly improved—can provide power for days.

By removing the expense of keeping humans alive on or under the sea, these technologies vastly expand the volume of the ocean which can be monitored and measured, whether it be for fishery management or weather prediction. They enable the better study of icebergs, underwater volcanoes and every living creature under the sea. And drones will soon be able to transfer data on all of this instantly back to shore from the middle of the ocean, over newly built internet infrastructure.

“When data start to inform decisions, very interesting things happen,” says Bilal Zuberi, a partner at Lux, a venture-capital firm. These things include investment in infrastructure. Mr Zuberi envisions herds of wind turbines moving around the seas autonomously, grazing on winds which offer the most power. The possibility of mining previously inaccessible seabeds may become a reality. So may the farming of fish in the open ocean. As befits their origins, the new technologies have military implications, too, as improved undersea surveillance makes it harder for submarines to hide, thus denting their second-strike capabilities.


Jacques Cousteau, a French conservationist, called in 1971 for a shift in how humans see the oceans. “We must plant the sea and herd its animals…using the sea as farmers instead of hunters,” he said. “That is what civilisation is all about.” It has taken half a century and a technological revolution, but the means of realising Cousteau’s vision are now here. This quarterly will examine the technologies that are enabling this virtual settlement of the seas, and the impact it will have. It will also examine the perils such changes could bring.

Modern civilisation has not shown much restraint in the use of technologies which make extracting resources from the earth or the seas easier, as the current overfishing crisis shows. The new developments will make it even simpler to drill or mine or fish in ways that could seriously damage the environment.

But the choice is not between taking these risks and taking no risks. It is about judging those risks against the capacity for wise regulation to reduce the risks already being taken—and to lessen the harm already being done to the seas, their inhabitants and those who rely on them. That capacity for good is also one that the new technologies will increase.

Harvesting ore underwater should be less disruptive on the sea bed than on land

PATANIA ONE sits in a large shed on the outskirts of Antwerp. Green and cuboid, with an interior steel frame, rubberised treads and pressure-resistant electronic innards, it is about the size of a minivan. In May 2017 it became the first robot in 40 years to be lowered to the sea floor in the Clarion Clipperton Zone (CCZ), about 5,000 metres beneath the Pacific ocean near where the Jasper did her pioneering sonar work. There it gathered data about the seabed and how larger robots might move carefully across it, sucking up valuable minerals en route.

The CCZ is a 6m square-kilometre (2.3m square-mile) tract between two of the long, straight “fracture zones” which the stresses of plate tectonics have created in the crust beneath the Pacific. Scattered across it are trillions of fist-sized mineral nodules, each the result of tens of millions of years of slow agglomeration around a core of bone, shell or rock. Such nodules are quite common in the Pacific, but the CCZ is the only part of the basin where the International Seabed Authority (ISA), which regulates such matters beyond the Exclusive Economic Zones (EEZs) of individual countries, currently permits exploration. Companies from Japan, Russia, China and a couple of dozen other countries have been granted concessions to explore for minerals in the CCZ. The ISA is expected to approve the first actual mining in 2019 or 2020.

Shock and ore

This could be big business. James Hein of the United States Geological Survey and colleagues estimated in a paper in 2012 that the CCZ holds more nickel, cobalt and manganese than all known terrestrial deposits of those metals put together. The World Bank expects the battery industry’s demand for these, and other, minerals to increase if the transition to clean energy speeds up enough to keep global temperatures below the limits set in the Paris agreement on climate.

One of the firms attracted by this vast potential market is DEME, a Belgian dredging company which has already proved resourceful in seeking out new businesses: installing offshore wind farms now provides it with revenues of nearly 1bn ($1.2bn) a year. Korea, Japan and China all have state-run research projects looking to dredge nodules from the deep sea with robots: “It really is a race,” says Kris Van Nijen, who runs DEME’s deep-sea mining efforts. At the moment his firm is setting the pace. It has learned a lot from the exploits of Patania One (pictured), such as how hard you can push bearings rated to 500 atmospheres of pressure and how deep treads sink into the deep-sea ooze for a given load.

The idea of mining the CCZ is not new. The Pacific’s mineral nodules were discovered by HMS Challenger, a British research vessel that first dredged the abyssal depths in the 1870s. Lockheed Martin, an American defence contractor, tried prospecting the CCZ in the 1960s. Its caterpillar tracks were not reliable enough to operate at such depth, so the company imagined two Archimedes screws to drag its vehicle through the mud. (Lockheed’s deep-sea mining expertise was later used in a CIA operation to recover a Soviet submarine which sank in the CCZ in 1968.) At the time there was hyped speculation that deep-sea mining would develop rapidly by the 1980s. A lack of demand (and thus investment), technological capacity and appropriate regulation kept that from happening. The UN Convention on the Law of the Sea (UNCLOS), which set up the ISA, was not signed until 1982. (America has still not ratified it, and thus cannot apply to the ISA for sea-floor-mining permits.)

Mr Van Nijen and his competitors think that now, at last, the time is right. DEME is currently building Patania Two, or P2, in an Antwerp shipyard. It will be deployed to the Pacific in 2019. Where P1 was basically a deep-sea tractor, P2 is a full-blown prototype. A sweeping nozzle mounted on its front (which gives it the look of a combine harvester) will suck up tonnes of nodules every minute; the power it needs to do so will flow down a thick umbilical from a mother ship above. In commercial production, a similar cord will pump a slurry of nodules and dirt back up to the ship—an impressive bit of engineering. For the time being P2 will just keep some of the nodules in a container on its back for later inspection.

In order to satisfy the ISA, this new machine does not just have to show it can harvest nodules; it also has to show that it can do so in an environmentally sensitive way. Its harvesting will throw up plumes of silt which, in settling, could swamp the sea floor’s delicate ecosystem. A survey of CCZ life in 2016 found a surprising diversity of life. Of the 12 animal species collected, seven were new to science. To help protect them, the mining field will be ringed with buoys, monitoring any plumes of silt that are bigger than DEME had predicted. The operations will also be monitored by a German research ship, funded by the EU.

If P2 succeeds, it will be time for P3, which will be the size of a small house. It will have two drone escorts, one to move ahead of it and one behind. They will monitor how much silt it disturbs, and will shut down the operation if necessary. Thus, P3 will be able to steer along the seabed autonomously. DEME will then build a customised surface vessel, ending up in about 2025 with a new kind of mining operation, at a total cost of $600 million.

The CCZ is not the only sea floor that has found itself in miners’ sights. Nautilus, a Canadian firm, says it will soon start mining the seabed in Papua New Guinea’s EEZ for gold and copper, though at the time of writing the ship it had commissioned for the purpose sits unfinished in a Chinese yard. A Saudi Arabian firm called Manafai wants to mine the bed of the Red Sea, which is rich in metals from zinc to gold. There are projects to mine iron sands off the coast of New Zealand and manganese crusts off the coast of Japan. De Beers already mines a significant proportion of its diamonds from the sea floor off the coast of Namibia, although in just 150 metres of water this is far less of a technical challenge.

If the various precautions work out, the benefits of deep-sea mining might be felt above the water as well. Mining minerals on land can require clearing away forests and other ecosystems in order to gain access, and moving hundreds of millions of tonnes of rock to get down to the ores. Local and indigenous people have often come out poorly from the deals made between miners and governments. Deep-sea mining will probably produce lower grade ores, but it will do so without affecting human populations.

It will also deliver those ores straight on to ships which can move them directly to processing plants on any coast in the world, including those using solar or wind power, thus reducing the footprint of mineral extraction even more. Having seen the destruction wrought by mining on land, undersea miners are working doubly hard to plough a different furrow.

Norway hopes to triple its aquaculture production by 2030

AN UNUSUAL object arrived off the coast of Norway last September. Roughly the weight of the Eiffel Tower and enclosing a volume greater than St Peter’s Basilica in Rome, its polyhedral frame measures 68 metres from top to bottom and over 100 metres in diameter. Parked 5km offshore, it looks like a partly submerged bright-yellow Ferris wheel tipped on its side, with a white control tower at its hub. Locals took it for a flying saucer as it passed South Africa on its way from the shipyard in China where it was built. (The picture below shows it before it was submerged.) Yet to come are its occupants: 1.5m baby salmon.

Ocean Farm 1, as the structure is known, is the first of six experimental fish farms ordered by SalMar, a Norwegian firm, at a total cost of $300 million. InnovaSea, an American firm, makes large open-ocean aquaculture nets called SeaStations, which are currently used off the coast of Panama and Hawaii, but Ocean Farm 1 is “by far the largest open-ocean fish farm in the world,” says Thor Hukkelas, who leads research and development on aquaculture at Kongsberg Maritime, a Norwegian engineering company. Mr Hukkelas’s team provided Ocean Farm 1’s sensor system: 12 echo sounders mounted on the bottom of the frame, high-definition cameras dangled into the water at different depths, oxygen sensors and movable, submerged feeding tubes.

Fish farming plays an increasingly central role in the provision of sufficient amounts of protein to Earth’s population. People eat more fish globally than beef, and farmed fish account for almost half of that amount (see chart). Many wild fisheries are already at or past their sustainable capacity, so efforts to make fish farming more productive are vital.

Ocean Farm 1 aims to automate what is an expensive and difficult business, and to solve two key problems that occur in near-shore aquaculture: that there is not enough space and that it is too polluting. The excrement from millions of salmon can easily foul up Norway’s fjords, and their shallow, relatively still water is a breeding ground for sea lice. In the open ocean the water is deeper and better oxygenated. The currents are stronger and so better able to sweep away excrement.

Near-shore farms normally spread feed on the water’s surface and allow it to sink, but Ocean Farm 1 has 16 valves at varying depths, through which feed can be pushed. By putting it farther down in the cage it is able to keep the salmon in deeper water. The salmon are fine with this. The sea lice, which like the shallows, are not.

All of this means the number of fish can be increased. The Norwegian government wants to triple its aquaculture production by 2030 and quintuple it by 2050. “Scaling up of traditional aquaculture is not going to reach these high-growth ambitions,” says Mr Hukkelas.

Kongsberg is gathering data from all the sensors on the farm to build a machine-learning model, called SimSalma, which learns the behaviour of the salmon in order to optimise their feeding. Currently, human operators on the structure decide when and where to feed the fish by examining the data. By 2019 Kongsberg plans to have automated this, pushing feed at optimum times and places and reducing human involvement. The success and expansion of such projects would represent a major step towards maintaining global fish stocks.

New technology could affect submarines' second-strike capabilities

ON JULY 20th 1960, a missile popped out of an apparently empty Atlantic ocean. Its solid-fuel rocket fired just as it cleared the surface and it tore off into the sky. Hours later, a second missile followed. An officer on the ballistic-missile submarine USS George Washington sent a message to President Dwight Eisenhower: “POLARIS—FROM OUT OF THE DEEP TO TARGET. PERFECT.” America had just completed its first successful missile launch of an intercontinental ballistic missile (ICBM) from beneath the ocean. Less than two months later, Russia conducted a similar test in the White Sea, north of Archangel.

Those tests began a new phase in the cold war. Having ICBMs on effectively invisible launchers meant that neither side could destroy the other’s nuclear arsenal in a single attack. So by keeping safe the capacity for retaliatory second strikes, the introduction of ballistic-missile submarines helped develop the concept of “mutually assured destruction” (MAD), thereby deterring any form of nuclear first strike. America, Britain, China, France and Russia all have nuclear-powered submarines on permanent or near permanent patrol, capable of launching nuclear missiles; India has one such submarine, too, and Israel is believed to have nuclear missiles on conventionally powered submarines.

As well as menacing the world at large, submarines pose a much more specific threat to other countries’ navies; most military subs are attack boats rather than missile platforms. This makes anti-submarine warfare (ASW) a high priority for anyone who wants to keep their surface ships on the surface. Because such warfare depends on interpreting lots of data from different sources—sonar arrays on ships, sonar buoys dropped from aircraft, passive listening systems on the sea-floor—technology which allows new types of sensor and new ways of communicating could greatly increase its possibilities. “There’s an unmanned-systems explosion,” says Jim Galambos of DARPA, the Pentagon’s future-technology arm. Up until now, he says, submariners could be fairly sure of their hiding place, operating “alone and unafraid”. That is changing.

Hello, buoys,

Aircraft play a big role in today’s ASW, flying from ships or shore to drop “sonobuoys” in patterns calculated to have the best chance of spotting something. This is expensive. An aeroplane with 8-10 people in it throws buoys out and waits around to listen to them and process their data on board. “In future you can envision a pair of AUVs [autonomous underwater vehicles], one deploying and one loitering and listening,” says Fred Cotaras of Ultra Electronics, a sonobuoy maker. Cheaper deployment means more buoys.

But more data is not that helpful if you do not have ways of moving it around, or of knowing where exactly it comes from. That is why DARPA is working on a Positioning System for Deep Ocean Navigation (POSYDON) which aims to provide “omnipresent, robust positioning across ocean basins” just as GPS satellites do above water, says Lisa Zurk, who heads up the programme. The system will use a natural feature of the ocean known as the “deep sound channel”. The speed of sound in water depends on temperature, pressure and, to some extent, salinity. The deep sound channel is found at the depth where these factors provide the lowest speed of sound. Below it, higher pressure makes the sound faster; above it, warmer water has the same effect.

Changes in the speed of sound (or for that matter light) cause sound (or light) waves to bend, a phenomenon known as refraction. The higher speed of sound above and below the deep sound channel thus bend sound back into it, allowing it to propagate for thousands of kilometres, especially if the sound’s wavelengths are long. It is a natural analogue to the process that keeps light in an optical fibre. Some zoologists believe whales use it as an ocean-wide telephone system.

In the POSYDON system, buoys on the surface would receive a GPS fix from satellites, then retransmit that data into the deep sound channel in acoustic form to submerged submarines and AUVs. Dr Zurk’s team is now determining the optimum frequencies for propagation, and modelling ways to correct for variable conditions. The simplicity of POSYDON would allow AUVs to off load a lot of the expensive equipment that they currently use to decipher positioning, says Dr Galambos. That means the possibility of more room on the drones for other useful stuff, or more money for more drones.

Even in heavily surveilled seas, spotting submarines will remain tricky. They are already quiet, and getting quieter; new “air-independent propulsion” systems mean that conventionally powered submarines can now turn off their diesel engines and run as quietly as nuclear ones, perhaps even more so, for extended periods of time. Greater autonomy, and thus fewer humans—or none at all—could make submarines quieter still. “As we pivot from manned to unmanned, no air cavity, maybe no propulsion motor, that’s a really challenging platform to find,” says Dr Zurk.

A case in point is a Russian weapon called Status-6, also known as Kanyon, about which Vladimir Putin boasted in a speech on March 1st. America’s recent nuclear-posture review describes it as “a new intercontinental, nuclear-armed, nuclear-powered, undersea autonomous torpedo”. A Russian state television broadcast in 2015 appeared to show it as a long, thin AUV that can be launched from a modified submarine and travel thousands of kilometres to explode off the shore of a major city with a great deal more energy than the largest warheads on ICBMs, thus generating a radioactive tsunami. Such a system might be seen as preserving a second-strike capability even if the target had a missile-defence system capable of shooting ICBMs out of the sky.

Despite such disturbing possibilities, many experts think that the balance of advantage is currently with seekers, not hiders. Sebastian Brixey-Williams of the British American Security Information Council thinks that “tracking and trailing” submarines will, within a decade, become significantly easier. Passive systems which simply listen will be a key part of this. Mr Brixey-Williams predicts that a few important choke points, such as the gap between Scotland and Iceland could now be completely surveilled by an array of just 15 acoustic sensors, far more sophisticated than the chain of hydrophones which did that job in the cold war. If a submarine is detected by such a system, it can then be trailed by another submarine, or some new form of drone.

New cold war

One part of the ocean that has become particularly interesting in this regard is the Arctic. Tracking submarines under or near ice is difficult, because ice constantly shifts, crackles and groans loudly enough to mask the subtle sounds of a submarine. With ever less ice in the Arctic this is becoming less of a problem, meaning America should be better able to track Russian submarines. Its Assured Arctic Awareness programme, also run by Dr Zurk, aims to develop new sensing techniques that can provide year-round monitoring without requiring a human presence. It is working on probes that can be deposited on the ice by drone, then melt their way down to the ocean beneath. Dr Zurk also talks of tagging icebergs with sensors, thus getting free rides across the ocean.

Greater numbers of better sensors, better networked, will not soon make submarines useless; but even without breakthroughs, they could erode the strategic norm that has guided nuclear thinking for over half a century—that of an unstoppable second strike. If a country even suspects that the location of its second-strike submarines might be known, their value for nuclear deterrence decreases. As Mr Brixey-Williams wrote in 2016: “The political tensions and threat to strategic stability that [tracking and trailing] would create should not be underestimated...and may be more dangerous than the technology itself.”

 

From sharks to ice shelves, monsoons to volcanoes, the scope of ocean monitoring is widening

IN NOVEMBER 2016 a large crack appeared in the Larsen C ice shelf off Antarctica (pictured). By July 2017 a chunk a quarter of the size of Wales, weighing one trillion tonnes, broke off from the main body of the shelf and started drifting away into the Southern Ocean. The shelf is already floating, so even such a large iceberg detaching itself did not affect sea levels. But Larsen C buttresses a much larger mass of ice that sits upon the Antarctic continent. If it breaks up completely, as its two smaller siblings (Larsens A and B) have done over the past 20 years, that ice on shore could flow much more easily into the ocean. If it did so—and scientists believe it would—that ice alone could account for 10cm of sea-level rise, more than half of the total rise seen in the 20th century.

The dynamics of the process, known as calving, that causes a shelf to break up are obscure. That, however, may soon change. Ocean Infinity, a marine-survey firm based in Texas, is due to send two autonomous drones under the Larsen C shelf in 2019, the first subglacial survey of its kind. “It is probably the least accessible and least explored area on the globe,” says Julian Dowdeswell, a glaciologist at the University of Cambridge who will lead the scientific side of the project.

The drones set to explore Larsen C look like 6-metre orange cigars and are made by Kongsberg—the same Norwegian firm that runs the new open-ocean fish farms. Called Hugin, after one of the ravens who flew around the world gathering information for Odin, a Norse god, the drones are designed to cruise precisely planned routes to investigate specific objects people already know about, such as oil pipelines, or to find things that they care about, such as missing planes. With lithium-ion-battery systems about as big as those found in a Tesla saloon the drones can travel at four knots for 60 hours on a charge, which gives them a range of about 400km. Their sensors will measure how the temperature of the water varies. Their sonar—which in this case, unusually, looks upwards—will measure the roughness of the bottom of the ice. Both variables are crucial in assessing how fast the ice shelf is breaking up, says Dr Dowdeswell.

The ability to see bits of the ocean, and things which it contains, that were previously invisible does not just matter to miners and submariners. It matters to scientists, environmentalists and fisheries managers. It helps them understand the changing Earth, predict the weather—including its dangerous extremes—and maintain fish stocks and protect other wildlife. Drones of all shapes and sizes are hoping to provide far more such information than has ever been available before.

Saildrone, a Californian marine-robotics startup, is looking at the problem of managing fish stocks. Its tools are robot sailing boats covered with sensors which it builds at something more like a factory than a shipyard on the island of Alameda in San Francisco Bay. These 7-metre, half-tonne vessels—it has so far built 20 of them, one of which is shown on the cover of this quarterly—are designed to ply the seas autonomously, using carbon-fibre wings as their sails. The wing has a fin attached to it which keeps it trim to the wind at all times. Its on-board computer (which has a GPS-equipped autopilot), its sensors and its radio get their modest 30 watts of power from lithium-ion batteries topped up by energy from solar panels whenever the sun is out.

One of the first hubs deploying these drones is at Dutch Harbor on Amaknak Island in Alaska; at any given time three of the boats based there are off monitoring a large pollock fishery in the Bering Sea, something they can do autonomously for up to a year before returning for maintenance. They gather data using echo-sounders designed by Simrad, a subsidiary of Kongsberg. Because each species of fish reflects different frequencies of sound in its own way (often because their swim bladders resonate differently) a sonar which emits a wide range of frequencies, as the wideband Simrad devices do, can tell what is a pollock and what is not.

Never mind the pollock

The drones supplement the fisheries’ main survey ship, which counts the pollock at the beginning of every season in order to determine how many fish can be caught. Their data give it a better sense of where to look. Sebastien de Halleux, Saildrone’s chief operating officer, says they also find more pollock, providing a count 25% higher than that of the official survey vessel. This may be because the drones cause less disturbance and drive fewer fish away. In time he thinks the drones might go beyond helping the existing system and do the job on their own, which would be a lot cheaper.

Pollock are good to eat, and if fisheries are managed sustainably they will remain so in perpetuity. But they are hardly the most exciting fish to monitor. That honour must surely go to the great white shark. Jayson Semmens, a marine biologist at the University of Tasmania in Australia, is using a new generation of sensor tags to study the behaviour of these fearsome fish in more detail than was possible before—not to protect people, as shark attacks are very rare, but to build a scientific understanding of their metabolism. He uses accelerometer data from a tag the size of a grain of rice, attached to the shark’s fin with a clamp, to calculate the energy it expends when it breaches out of the water.

The tags are too small to have enough power to send their data straight back to base. But they do not need to be retrieved directly from the shark (which is probably just as well). Their attachments dissolve over the course of their life, so in time they float free, rising to the surface and emitting a simple signal that allows them to be found. Armed with the data they record, Dr Semmens can calculate the fish’s total energy needs, and thus how much prey a single shark requires. That can be used to gain an understanding of the flow of energy through the food chain, which is basic to understanding the dynamics of the ecosystem. The flow of energy through terrestrial ecosystems is comparatively easy to study; marine ones are more mysterious.

A tiny sensor that measures a shark’s metabolism seems remarkable—but at heart it is no more so than a modern phone. “The accelerometer I use to measure great white shark activity,” says Dr Semmens, “is the same one you use to turn your smartphone into a lightsabre.” Such tiny tags, which can also measure the temperature and pressure of the surrounding water, are a big step up from the bulky tags of yesteryear, which would provide a single acoustic frequency that allowed researchers to follow the fish if they were close enough. And they are improving rapidly. “People are talking about tags which sample blood from animals underwater,” says Dr Semmens.

The same technology can be used for environmental monitoring as well as pure science. Dr Semmens has tagged several endangered Maugean skate in Tasmania’s Macquarie harbour with somewhat larger sensors—they weigh 60 grams, instead of 10—that measure heart rate and the dissolved oxygen content of the water. Parts of the harbour are becoming anoxic—deprived of oxygen—because of large-scale near-shore salmon farming. The data from the skate show how much of this is going on, and how much harm it is doing. That makes it easier to argue for changes that boost conservation efforts.

One of the biggest benefits of better measured seas is the possibility of getting to grips with dramatic weather events. The top 3 metres of the oceans hold more heat energy than the entire atmosphere. How much of that energy escapes into the air, and when and where it does so, drives the strength and frequency of storm systems. And there is ever more energy to do that driving. The average surface temperature of the seas has risen by about 0.9°C (1.6°F) in the past hundred years, according to America’s National Oceanic and Atmospheric Administration. This means that, since the 1980s, about a billion times the heat energy of the atom bombs dropped on Hiroshima and Nagasaki has been added to the ocean—roughly an atomic explosion every few seconds.

Yet even as the amount of energy the oceans hold has risen, the details of its transfer to the atmosphere remain unknown for large swathes of the ocean. This is particularly important when it comes to understanding something like the South Asian monsoon. The rains are driven by the huge size of the Bay of Bengal and the amount of fresh water that pours into it from the Ganges and Brahmaputra river systems. Because this buoyant fresh water cannot easily mix with the denser salty water below it, the surface gets very warm indeed, driving prodigious amounts of evaporation. Better understanding these processes would improve monsoon forecasts—and could help predict cyclones, too.

That’s why it’s hotter under the water

To this end Amala Mahadevan of Woods Hole Oceanographic Institute (WHOI) in Massachusetts, has been working with the Indian weather agencies to install a string of sensors hanging down off a buoy in the northern end of the Bay of Bengal.

A large bank of similar buoys called the Pioneer Array has been showing oceanographers things they have not seen before in the two years it has been operating off the coast of New England. The array is part of the Ocean Observatories Initiative (OOI) funded by America’s National Science Foundation. It is providing a three-dimensional picture of changes to the Gulf Stream, which is pushing as much as 100km closer to the shore than it used to. “Fishermen are catching Gulf Stream fish 100km in from the continental shelf,” says Glen Gawarkiewicz of WHOI. These data make local weather forecasting better.

Three other lines of buoys and floats have recently been installed across the Atlantic in order to understand the transfer of deep water from the North Atlantic southwards, a flow which is fundamental to the dynamics of all the world’s oceans, and which may falter in a warmer climate.

Another part of the OOI is the Cabled Array off the coast of Oregon. Its sensors, which span one of the smallest of the world’s tectonic plates, the Juan de Fuca plate, are connected by 900km of fibre-optic cable and powered by electricity cables that run out from the shore. The array is designed to gather data which will help understand the connections between the plate’s volcanic activity and the biological and oceanographic processes above it.

A set of sensors off Japan takes a much more practical interest in plate tectonics. The Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) consists of over 50 sea-floor observing stations, each housing pressure sensors which show whether the sea floor is rising or falling, as well as seismometers which measure the direct movement caused by an earthquake. When the plates shift and the sea floor trembles, they can send signals racing back to shore at the speed of light in glass, beating the slower progress of the seismic waves through the Earth’s crust, to give people a few valuable extra seconds of warning. Better measuring of climate can save lives over decades; prompt measurement of earthquakes can save them in an instant.

Better satellite connectivity, robot boats and torpedo drones are helping

THE first use the modern world made of the oceans’ depths was to run telegraph cables across them. That opened up a new era of intercontinental communication and spurred a new scientific interest in the abyss. Both enterprises have prospered: single cables now carry as much as 160 terabits across the Atlantic every second; oceanographers have mapped and drilled into the ocean floor around the world. But they have not come together. It is now very easy to get vast amounts of data from one side of an ocean to another; but it is hard to get even modest amounts of data out from the ocean itself. A new infrastructure is needed to enable sensors at sea to transfer their data back to land.

Sebastien de Halleux of Saildrone, the firm whose drones keep an eye on Alaska’s pollock, dreams of doing much more than that. Saildrone recently increased its build-rate from one a month to one a day; by 2021 Mr de Halleux wants to have a thousand of his little craft sailing the seas. A full Helen of Troy’s-worth sounds extravagant. But it is important to put it into context. First, smartphone components make such boats cheap; Mr de Halleux thinks he can build the whole fleet for less than the cost of one research vessel (roughly $100m). Second, the ocean is very big. Divide its surface into 1,000 pieces and each one is still the size of Japan. That is quite a lot of ground for a single little boat to cover.

There is already one research network considerably larger than this. An international collaboration called Argo has a regularly replenished fleet of nearly 4,000 untethered buoys (see map) which divide their time between the surface and the depths, drifting at the whim of the currents. Over ten-day cycles they sink slowly down to about 2,000 metres and back up, measuring temperature and salinity as they go. Their data have revolutionised oceanographers’ understanding of their subject. But the network is still sparse—one float for every Honduras-sized patch of ocean.

Though restricted to the surface, Saildrone’s craft are much more ambitious. They will not just monitor temperature; they will track fish and pick up pollutants, analyse carbon-dioxide and oxygen concentrations in the water, record the height of the waves and the speed of undersea currents, feel variations in the magnetic field and more. There are already markets for some of these data: weather forecasters, fisheries managers, oil and gas companies. For others the scheme has a “Field of Dreams” approach: build the data set and they will come.

Saildrone has so far raised $29m for this work. Ion Yadigaroglu, managing partner of the Capricorn Group, one of the investors, compares the company to Planet, a satellite company in which Capricorn has also invested. Planet has used smartphone technology and Silicon Valley agility to produce a constellation of over 100 small satellites. They provide images of every spot on Earth every day, allowing all sorts of new insights and monitoring possibilities. “Planet is a scanning platform for the Earth,” he says. “Saildrone wants to be a scanning platform for the oceans.”

Planet, though, has been able to build a network of ground stations to get its daily terabits of data down from the satellites passing overhead and out to customers. For Saildrone, where the data start off on the surface, the equivalent would be to build its own satellite network. This it cannot afford to do, so, like Argo, it uses satellite services provided by others. And these are expensive.

Argo can afford such satellite services because its floats produce relatively little data—a quick spurt every ten days or so. Saildrone boats produce far more, and so currently have to throw almost all of it away. Mr de Halleux says the drones’ filtering algorithms cut the data down by a factor of 60 before transmission. If the company knew exactly what data the market would put most value on that might be acceptable. But with data never routinely gathered before it does not know.

Systems are also needed to get data out of the depths and up to the surface. Eamon Carrig, co-founder of Autonomous Marine Systems (AMS), based in Massachusetts, seeks to meet that need, providing “power, communications and bandwidth for other projects”. His “datamarans”, which also rely on wind for free propulsion using a solid “wing” sail, are smaller and cheaper than those built by Saildrone. They are designed to deploy sensors and buoys for third parties, such as Argo, and also to act as relays for things which can communicate only through sound.

Jayson Semmens of the University of Tasmania, who tracks sharks with tiny sensors, says that what he would really like to do would be to “track animals that never break the surface, and find a way to exfiltrate data from them”. Among other things, live data from underwater animals would allow conservation biologists to manage ecosystems directly, instead of making decisions based on historical averages. It might be possible to get such data swiftly from fish to shore using a local network of AMS drones equipped with acoustic modems as an intermediary.

Other schemes exist for allowing connectivity to pop up as and when needed and swim away when all is done. Jeff Smith of Riptide Autonomous Solutions, a drone company also based in Massachusetts, is working with POSYDON, a programme run by DARPA, to build a system of small torpedo drones which will swim out and create a temporary acoustic communications chain in any area of the ocean that needs it, bouncing information from drone to drone.

The more of such systems there are, the wider the range of research which will be possible—especially if standards now being developed allow all the different systems to talk to each other. New buoys could add to the data Argo provides in particular places of interest without the need for a research ship to schlep out and deliver them. New types of buoy could be added, too. Last year Paul Allen, a co-founder of Microsoft, announced that he would spend $4m on 33 new Argo floats which could go down far deeper than the current ones, profiling temperature, pressure and salinity to a depth of 6,000 metres.

What is most needed, though, is a new generation of satellite internet to get data from the surface to the shore. Happily this seems to be on the way. Various companies are racing to deliver high-bandwidth internet to the entire surface of the Earth using hundreds of small, cheap satellites in low orbits. SpaceX, Elon Musk’s rocket business, launched its first prototypes on February 22nd. The main beneficiaries are likely to be people in areas not served by current infrastructure. But to serve all those parts of the world, these services need to serve all the oceans, as well.

The bottom line

With satellite connectivity available at the surface, and acoustic systems deployed as and when needed below, there would be one more thing needed to complete the picture: a map of the ocean floor. Valuable in itself, it would also be a great help to underwater vessels trying to navigate or to prospect for minerals. Being able to compare what sonar shows below you with a map stored on board would make things a lot easier.

The best overall maps of the ocean floor to date have been made from space. Large underwater features like mountains and trenches exert a gravitational influence on the water above them, subtly changing the shape of the surface. Orbiting altimeters can measure those small excursions from mean sea level, and computers can use that data to infer what the sea-floor topography responsible for it looks like. This has produced maps with an average horizontal resolution of 5km—good for getting the gist of things, but little help to a drone trying to find its way.

Maps made with modern sonar systems towed behind research ships are better, but currently cover only 10% of the ocean floor at high resolution. Jyotika Virmani, an oceanographer working at XPRIZE, a non-profit outfit which gives awards for technological progress, is trying to improve this. Nineteen teams from around the world have entered the competition she is running to map the sea floor without using any human-piloted craft at all. The first round of the competition asked the teams to map 100 square kilometres of seabed to a five-metre resolution in under 16 hours. Next year the second round will ask for the same resolution over 250 square kilometres in a day. Ms Virmani is hoping the whole seabed will be mapped to a resolution of 100 metres or better by 2030.

That will not be an end to the mysteries of the deep. But it will mark a new era in their exploration. With easier communications from any point of the surface, a clearer idea of what lies below each of those points, and ever better sensors populating the volume in between, the oceans will be much better known. This will not make them any less marvellous. But it should make it easier to preserve their marvels.

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