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Fifteen

Sounds like a good idea

Interview: Professor Peter Tyack, Dr Mark Johnson & Dr Lars Boehme…

Sounds like a good idea

Sounds like a good idea

Interview: Professor Peter Tyack, Dr Mark Johnson & Dr Lars Boehme

Researchers at the Scottish Oceans Institute Sea Mammals Research Unit in St Andrews are using smart technology mounted on marine mammals to understand their complex behaviour – and the impact of human activity on marine ecosystems.

It's a long way from bouncing around in a boat off the coast of Hawaii, lowering microphones into the sea, to sitting in his office in the east of Scotland 40 years later, analysing gigabytes of data from whales. It’s also a long way from the surface of the ocean to the mysterious world 2,000 metres below where some whales hunt for food.

Professor Peter Tyack (left), who is now based in the Sea Mammals Research Unit (SMRU) of the Scottish Oceans Institute (SOI) in St Andrews, has always been fascinated with the sounds of whales and dolphins, but it has taken him several decades to make sense of their calls and songs and how they are affected by “acoustic fog” or ambient noise in the ocean.

To understand the scale of the problem, you have to consider that some whales only come to the surface five per cent of the time and spend the rest of their days in the depths where the Sun never shines. “You can hear them but you can’t watch what they’re doing,” says Tyack. In addition, until very recently, not much was known about what goes on under the water. For example, it was only in the 1930s that scientists established that fish can hear, when Karl von Frisch taught catfish to respond to his whistling. In the 1940s, acoustic oceanography was starting to reveal the sounds of undersea animals, but it was not until the 1950s and 1960s that scientists were able to identify the sounds of many whale species. When Tyack was a student in the early 1970s (biology at Harvard then his PhD in Animal Behaviour at Rockefeller University), the science was still very basic. There were various theories about the behaviour of dolphins and whales, but hardly any evidence.

Tyack’s early research focused on the songs of humpback whales. Whilst some of the team used a theodolite to follow the whales from the land, others did their best to follow on the water, using special underwater microphones to record the songs of males in search of females.

One of Tyack's main concerns over the years has been the effect of anthropogenic noise (sounds made by humans) on these undersea creatures. It has been estimated that since the beginning of the industrial age, ambient noise (e.g. from engines and propellers), has reduced the useful range of blue whale calls from about 1,000km to a current maximum of about 400km.

“To compensate for this,” says Tyack, “whales sing louder and repeat the message more often. When faced with low-frequency noise, they also sometimes change from bass to tenor.”

The problem caused by humans not only results in a change of behaviour, but can also endanger the whales, sometimes causing them to strand and die. Scientists started to think that sonar was the cause of the problem in the early 1990s, but it has taken almost 20 years to prove it.

Tyack has experimented with different acoustic technologies since the 1980s. One early project helped identify the individual “whistles” of dolphins. When two dolphins were in the same pool, and one of them called to the other, it was impossible to tell which one was making the noise by observing the dolphins. By fitting them with very basic microphones, however, Tyack was able to identify which dolphin made which whistle. This method allowed him to confirm that each dolphin produces an individually distinctive signature whistle, and to discover that they can imitate the signature of a partner.

The next challenge was to record sound and monitor other activities by sticking electronic tags on whales, seals and dolphins. Working at the Woods Hole Oceanographic Institution in Massachusetts, Tyack then teamed up with Dr Mark Johnson to develop more sophisticated devices, incorporating movement and orientation sensors as well as recorders – taking advantage of recent advances in mobile phone technology.

Johnson's introduction to biology was one night at a party, when a student told him all about a technical problem which Johnson believed he could solve – he has a PhD in Electronic Engineering from the University of Auckland in New Zealand. Soon he was “becoming a biologist,” and today he's working next door to Tyack in St Andrews, where they collaborate with about 30 other researchers. Both Tyack and Johnson were brought to Scotland thanks to funding from MASTS (the Marine Alliance for Science and Technology for Scotland) as part of the programme to enhance marine capacity in Scotland.

“We not only carry out blue-sky research and study undersea mammal behaviour but also gather data which has real-world applications,” says Tyack. Protecting rare species is one thing, he says, but the research they do is equally important to the future of the fisheries and offshore energy industries, because all marine life is affected in some way by human activities. The data which is gathered from various different devices (including those which measure temperature) can also be used as a proxy for measuring the impact of climate change and human interference with the marine environment. “Blue-sky research can uncover applied problems, and applied research can lead to blue-sky discoveries,” adds Tyack.

One example of applied research is studying how noise affects whales – e.g., naval sonar and the airguns used for seismic exploration. Because it is illegal to kill whales, and the US Navy had been blamed for a number of strandings in the late 1990s, it was important to establish whether or not naval sonar disrupted the normal behaviour of whales. In the year 2000, the US Navy ruled out all other factors in one mass stranding, and Tyack later demonstrated, using his new digital devices, that sonar did indeed trigger strong responses that could pose a risk of stranding. One technique involved emitting simulated sonar, then recording the response of the whales, and this year Tyack published a paper that “established the level of sound that started to disturb the behaviour of Blainville’s beaked whales, helping to establish criteria for safe exposure.”

Another practical problem is collision with ships. Why do whales sometimes appear not to hear ships? Should ships make more obvious sounds to warn marine mammals away? The answers may not just protect the mammals but also the ships.

Sometimes, the behaviour of the whales appears random, says Johnson, but when you analyse the data, a pattern emerges. “Whales are finely tuned systems,” says Johnson, “and to understand the impact of ambient noise, you first have to understand normal behaviour.”

Another recent project used passive acoustic data (listening for whale sounds) to estimate the population of undersea mammals – almost impossible and sometimes even dangerous if scientists rely on visual observations alone. And the results of this study may even be useful in assessing insect and bird populations, using similar statistical methods to analyse the data.

It is impossible, however, to disentangle curiosity-driven research from more obviously “practical” projects, says Tyack. In order to protect the different species, we first have to understand how they behave.

Smart technology

The underwater acoustic recording tags developed by Tyack and Johnson since they first teamed up in Massachusetts have improved significantly over the years – especially their memory capacity. Their collaboration resulted in the first widely-used sound recording tag for marine mammals, combining high-resolution acoustic and movement sensors, and the tags are now used worldwide. One major challenge, says Johnson, is that even though they may “work great on the bench,” ultimately these very clever devices are stuck on animals which dive down to the bottom of the sea. They need to be extremely robust and small enough not to be noticed (the less invasive, the better), but the key challenge is integration, says Johnson.

The latest devices are capable of sampling very detailed data, recording the sounds of the whales as well as the sounds that the whales hear – not just the ambient noise in the ocean, but also echoes from the echolocation sounds emitted by whales to navigate and hunt. In addition, the new generation of tags is equipped with accelerometers, magnetometers and motion detectors which indicate the orientation of the whales and their direction of travel. Added together, this data allows them to reconstruct the “journey” of the whales over a period of a day or more – the limitation is the size of data storage on board.

As well as storage, battery and other equipment, will cameras ever be fitted? At the bottom of the deep ocean, there is not much to see and the images may not reveal much, says Tyack, “The key for understanding animal behaviour is to use sensors that match the sensory capabilities of the animals.” When the tags come off the whales, flotation chambers take them back up to the surface where they send out a signal which enables the research team to locate and retrieve them, then download the data. By adding GPS, they would also be able to retrace the route of the whales more precisely.

Since he started developing tags to sample behaviour, Tyack has taken full advantage of advances in digital technology to drive his research. “If you can't solve a problem today,” he explains, “just wait another six months.”

Because data storage is limited (currently about 30Gb), researchers only get a very brief glimpse into life underwater and must prioritise what data to collect (e.g. which frequency range to detect). There is always a trade-off, says Johnson – especially between environmental and behavioural data. But according to Dr Lars Boehme (right), a MASTS Lecturer at the SOI who specialises in oceanography, “if you understand the habitat, you understand the species.”

“The seals call home”

The SOI is also “making waves” in oceanography, using very similar tagging devices to map the oceans, using seals to carry the tags which send back a wide range of data, including temperature and evidence of photosynthetic plankton, as well as seal behaviour. Instead of waiting to retrieve the tags when they drop off, the researchers use satellites to pick up the signal in real time, whilst still attached to the host. There are two types of tags – one which uses satellite telemetry and another based on mobile phone technology, and every time they surface, “the seals call home,” says Boehme. “It’s like tweeting,” he adds, because they only send back a few bits of data, compared to gigabytes on other devices.

The instruments used by Boehme measure salinity and temperature throughout the winter in the Antarctic, when it's almost impossible to gather the data because of the pack ice. According to Boehme, the devices also provide behavioural data which shows “the sensitivity of top predators to global and regional-scale climate variability.” The data are also more detailed than anything gathered before. Over the last 150 years, he explains, scientists in the Antarctic got only about 13 temperature profiles from the southern Weddell Sea during the winter, but using seals – which dive under the ice to a depth of about 500 metres – produced about 2,500 profiles in a matter of weeks.

Interdependence

Other studies illustrate the interdependence of oceans and species. Boehme says that by studying the impact of climate variability on animals, it helps us understand the impact on ourselves, whilst Tyack describes their research as “not only a window on marine mammals but the ecosystem as a whole.”

The work done by the oceanographers and marine mammal researchers at the SOI is a great example of how collaboration can be “greater than the sum of its parts,” says Tyack. For example, he and Johnson work as a part of a team of about 30 people, including Boehme. In addition to biologists and electronics engineers, the team uses specialists in materials technology (salt water and electronics don't mix) and mechanical engineers, as well as statisticians, programmers and physicists. To some extent, says Boehme, he has “piggybacked” on marine mammal research, but the end result is data that are useful to everyone, and everyone also gets involved in analysing the data and designing the tags.

For Tyack and Johnson, the specialisations of different team members are even more complex, and they rely on an extensive pool of scientists in Scotland and beyond. MASTS has also enabled them to move on from a world-class institution in the United States to an “amazing constellation” in St Andrews and a “synergistic network” of researchers in Scotland, functioning together in a way that no other country can offer, they say. “One of the main strengths of MASTS is its ability to attract international researchers,” says Tyack. For Boehme, MASTS has also meant a huge change in direction. A physicist recruited by St Andrews seven years ago, he now has long-term funding and easier access to the other resources and people that MASTS has brought together at the SOI and other institutions in Scotland. “My focus has changed from next year's salary to good science,” says Boehme.

The “good science” at the SOI will also have an impact far beyond its own walls. “What we are doing also matters to industry,” Tyack explains. “We are developing new methodologies and new technologies that industry (e.g., fisheries, shipping and oil and gas companies) can use to analyse environmental impact. This is essential to protect marine life and to meet regulatory requirements. Some of the new monitoring technologies allow industry to operate when it would otherwise be prohibited, speeding up projects and saving tens of millions of pounds every year.”

There is also a strategic “higher purpose,” says Tyack, because their work is useful to environmental protection – in Scotland and beyond. “There is a disconnect between people’s knowledge of environmental issues and the ocean,” says Boehme, “but it is critical to see the connection.”

Forty years ago, Tyack had a dream – to understand the behaviour of mammals which are out of sight most of the time. But by joining forces with other people, sharing data and being creative, his dream has begun to come true. “And now we have more dreams,” says Tyack.

 

 

 

"Sounds like a good idea". Science Scotland (Issue Fifteen)
Printed from http://www.sciencescotland.org/feature.php?id=224 on 24/09/17 11:28:55 AM

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