The World’s Fishermen as a Maritime Sensor Network
September 2nd, 2022
Via the U.S. Naval Institute, commentary on the potential – via use of a crowdsourcing platform – the world’s fishermen can become a martime sensor network to counter illegal, unreported, and unregulated fishing:
As a topic, illegal, unreported, and unregulated (IUU) fishing needs little introduction. The U.S. Coast Guard Commandant’s 2020 Strategic Outlook stated that IUU fishing “has replaced piracy as the leading global maritime security threat.”1 Indiscriminate IUU fishing techniques, such as drift net release and dynamite detonation, result in annual losses of $37 billion to maritime nations.2 Besides monetary losses, IUU fishing deprives indigenous coastal communities of needed sustenance, which increases poverty and the risk of low-intensity conflict.
Coincidentally, China is one of the world’s worst IUU fishing offenders. Furthermore, China has outfitted its industrial fishing fleet with hardware and collection capabilities that make its boats paramilitary maritime forces. It is a matter of national security to track and interdict these long-ranging fishing vessels, but thus far the U.S. Coast Guard has been unable to field a technology that offers sufficient density of coverage and microfidelity.
A Math Problem Satellites Cannot Solve
Tracking the Chinese fishing fleet largely amounts to a math problem. There currently are an estimated 17,000 high-endurance Chinese fishing vessels capable of operating both as swarms and as dispersed entities.3 Spreading these vessels out over the millions of square miles of other nations’ exclusive economic zones (EEZ) leads to a quintessential needle in the haystack problem.Existing tracking efforts rely heavily on “eye in the sky” technologies that find and ping Chinese fishing boats, where the data is then processed by specialized AI companies. These technologies can be broken into five buckets (see Figure 1) and boast impressive capabilities, but capability gaps remain (see Figure 2).
The Coast Guard has championed orbital technologies, as seen in the Defense Innovation Unit’s recent X3View challenge.4 However, the Coast Guard should also investigate prototyping and deploying low-cost crowdsourced data platforms to provide “ground truths” in addition to these overhead collections.
An Agile Solution
Crowdsourced data platforms should be publicly available, compatible with low-end smartphones, and free to use. Local fishermen can then report Chinese vessels engaging in IUU activities in those fishermen’s sovereign waters. Reports could be broadcasted back to other platform users, the partner nation coast guard (if applicable), and the U.S. Coast Guard. The most analogous way to think of such a platform would be like the driving app Waze, but instead of reporting traffic or speed traps, fishermen would report Chinese vessels engaging in IUU fishing.This nonstandard intelligence, surveillance, and reconnaissance (ISR) could greatly augment the Coast Guard’s detection abilities when employed as a tip-and-cue model. A fisherman’s report would be the “tip,” which allows the Coast Guard to direct private satellite, synthetic-aperture radar (SAR), or radio-frequency operators to “cue” their satellites onto specific patches of ocean. Consistently generating tasking for space assets is far more efficient than sweeping large swaths of the ocean and hoping to get a cold hit. Given the number of fishermen in the Indo-Pacific, this form of ISR would have incredible density of coverage.
Furthermore, if the reports included pictures, then the Coast Guard could obtain valuable amplifying data, such as hull number and cargo on deck. Space assets cannot easily discern hull numbers or draft. In the longer run, data collected by such a platform could be combined with weather and overhead collections to build predictive models of where the Chinese fishing fleet will operate each month.
A crowdsourced platform also could be used in the information operations domain. Pictures and videos of the Chinese fishing fleet employing outlawed fishing practices could be used in press releases to emphasize China’s flagrant violations of good maritime stewardship. Interviews with fishermen in the Philippines reveal that they detest the Chinese fishing fleet presence yet feel like many of their fellow countrymen are unaware of their plight.8 Uniting local seafaring communities via technology would have additional positive effects.
Multiple Proceedings authors have discussed the need to address China’s gray-zone tactics with counterinsurgency (COIN) tactics.9 COIN relies heavily on a positive rapport between blue forces and the local populace. Providing maritime communities with free technology that makes their time at sea safer and more productive would be a good first step in building such a rapport.
The biggest challenge would be getting the fishermen to use the platform and make reports. For starters, the platform would be simple to use and free to download. Once downloaded, a fisherman could view the last known position of hostile Chinese vessels. This is highly valuable since an encounter with Chinese fishing vessels often results in the local fishermen getting their nets cut or vessels rammed.10 And by making reports, a fisherman would indirectly help their comrades avoid unexpected encounters with the Chinese fleet.
The use of crowdsourcing in a contested environment is not unprecedented; during Russia’s invasion of Ukraine, Ukrainian civilians have increasingly used crowdsourcing applications to report the movements of Russian Army forces.11 The Philippine Navy has had limited success in getting Filipino fishermen to report Chinese maritime militia vessels over via radio, but expressed a need for a more centralized mobile platform.12
Technical Merit and Cost
It is relatively easy to develop a crowdsourced platform. Dozens of such apps exist, although this specific platform would have to be custom built to function offline.13 Basic security and encryption would be essential, and it also would be wise to not require fishermen to include personal identification information (other than an email) when creating an account. Sending the reports’ metadata to an established server provider such as Amazon Web Services would further increase the data’s security and ability to be integrated with Coast Guard dashboards. Back-end quality assurance/quality control programs would serve as filters if China tried to flood the platform with misleading reports.While space-based assets cost millions of dollars to launch and operate, a crowdsourcing platform could be built for $100,000 and maintained for even less. A team of Stanford University students working on a similar Hacking 4 Defense project were able to field a maritime domain awareness minimum viable product for only $20,000. Making the platform compatible with smartphones would remove the need for custom-built hardware and drive costs down. Furthermore, the potential user base is immense.
Deployment
The U.S. Coast Guard specializes in building partnerships with fishing communities and fisheries enforcement agencies, both domestically and internationally. Once the first version of the platform is built and beta tested, the Coast Guard should showcase it to partner nations. Since the platform would be easy to use, training would take a matter of minutes. Countries most affected by Chinese IUU fishing—such as Ecuador, the Philippines, Micronesia, and Fiji—already have established relations with the U.S. Coast Guard, making institutional buy-in all the easier.Looking Forward
IUU fishing is a problem for the entire Departments of Defense and Homeland Security.14 However, the Coast Guard is best positioned to take on the challenge. To make maritime domain awareness (MDA) more robust, the Coast Guard should prototype a simple crowdsourced MDA platform, which does not have the upfront cost of exquisite surveillance assets. Such a platform would improve the Coast Guard’s capability to interdict Chinese IUU fishing, while simultaneously mobilizing local communities. For years, the act of exposing IUU fishing has largely been done by governments and a few specialized non-governmental organizations. The scope of the problem now demands an all-hands-on-deck effort that incorporates simple reporting by concerned and impacted local watermen.1. U.S. Coast Guard, Illegal, Underreported, and Unregulated Fishing Strategic Outlook, U.S. Department of Homeland Security, September 2020.
2. “Illegal Fishing,” World Wildlife Foundation, 2022, www.worldwildlife.org/.
3. Ian Urbina, “How China’s Expanding Fishing Fleet Is Depleting the World’s Oceans,” Yale Environment 360, 17 August 2020.
4. “U.S. Government and Nonprofit Organization Host Prize Competition to Leverage the Latest Technology to Detect and Defeat Illegal Fishing,” Defense Innovation Unit, 22 July 2021
5. Uday Govindswamy, Planet Labs, interviewed by author, 26 March 2020.
6. Michael Boito, et al., “Metrics to Compare Aircraft Operating and Support Costs in the Department of Defense,” RAND Corporation, 2015.
7. Brendon Providence, Volpe National Transportation Systems Center, U.S. Department of Transportation, interviewed by author, 10 March 2020.
8. Joyce Hufton, Coral Movement, interviewed by the author, 13 December 2020; Yoyong Suarez, IMPL Project, interviewed by the author, 6 June 2020; and Dr. Francisco Buencamino, Tuna Canners Association of the Philippines, interviewed by the author, 25 March 2020.
9. Hunter Stires, “The South China Sea Needs a ‘COIN’ Toss,” U.S. Naval Institute Proceedings 145, no. 5 (May 2019); and 2ndLt Robert German, USMC, “The Other Side of COIN,” U.S. Naval Institute Proceedings 147, no. 2 (February 2021).
10. Anonymous U.S. Army Green Beret, interviewed by the author, 18 December 2020.
11. Drew Harwell, “Instead of Consumer Software, Ukraine Tech Workers Build Apps of War,” The Washington Post, 24 March 2022.
12. CDR Cyrus Mendoza, Philippine Navy, interviewed by the author, 13 January 2021.
13. Marguerite Reardon, “Can Dataless Smartphones Still Use GPS Navigation Apps?” CNET, 13 March 2013.
14. Dr. Joseph Felter, Stanford University, Hoover Institute, interviewed by author, 10 March 2020; CAPT Michael O’Hara, USN, U.S. Naval War College, interviewed by author, 19 June 2020; COL Leo Liebreich, U.S. Army, interviewed by author, 29 May 2020; and CAPT Chris Sharman, USN, interviewed by author, 5 March 2020.
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Read More »‘Fitbit For Whales’ and Other Tagging Tech Help Reshape Wildlife Conservation
August 19th, 2022
Via Mongabay, a look at how a ‘Fitbit for whales’ and other tagging tech are helping to reshape wildlife conservation:
When Alexandra Ross started her study on bridled nail-tail wallabies in central Queensland in Australia in 2017, the wildlife ecologist had a pressing concern. The species was already categorized as endangered by the Australian government, and a previous study had shown that these pint-sized kangaroo cousins (Onychogalea fraenata) panicked when they were fitted with heavy radio collars. Even worse, the collars sometimes got hooked onto a tree or a fence, choking the animal to death.
“Losing even one would be really bad,” Ross tells Mongabay in a video interview. “So we had to figure out a way to let them not get choked.”
With a lean budget making the purchase of expensive collars difficult, Ross went on to make a DIY collar. She attached a radio transmitter to an elastic cat collar with the help of small cables and super glue. The easily available cat collars were light and designed for long-term use. Their elastic nature made them easier for the wallabies to wriggle out of without choking. The results from her study, published in the journal Australian Mammalogy in 2021, showed that 25 out of the 39 collars she attached to wallabies remained in place for more than four months. Two wallabies were found to be agitated, but the study determined that other factors, including pouching of young ones, also played a role in causing that stress.
Ross says her collar could be replicated for any species with a neck. The goal, she says, is to reduce stress and injuries to animals during research or conservation activities. “Everything we do as scientists is intrusive,” she says. “But we are trying to be as minimally intrusive as possible with the end goal of helping them.”
Ross’s relatively cheap and ingenious collar is part of an ever-evolving generation of tagging and tracking devices used to study and protect wildlife. While her design might lie at the rough end of the spectrum, more advanced innovations are also being increasingly developed and deployed at the more refined end. The use of widely available consumer technology in many of them means they can potentially be scaled up and adapted for use across many different species of animals.
Estimating the impact on animals from the tagging techniques used to keep track of them is a tough task because there aren’t extensive studies on the subject. A 2011 study published in the journal Wildlife Research found that there is a “preponderance of studies focused on short-term effects, such as injuries and behavioral changes,” that tagging and marking techniques have on animals—including pain, impact on maternal attendance, and duration of foraging trips. While the techniques were not found to affect survival, the study found that “no published research has addressed other possible long-term effects.”
Despite the lack of research, conservation scientists and experts advocate the need to keep adopting newer methodologies and technologies to reduce any impact their work might have on animals. Biologist L. David Mech has been studying wolves (Canis lupus) in North America since 1958 and has seen firsthand how the development of new technology has reshaped the study and conservation of wildlife.
“When the first radio [transmitter] was put on animals in the 1960s, it was totally revolutionary and changed wildlife research tremendously by orders of magnitude,” he tells Mongabay in a video call.
Early on in his career, Mech says, it was impossible to locate a specific wolf. But that changed in November 1968 when he took a flight to track the first wolf he had fitted with a radio collar. “Suddenly, I merely listened to a ‘beep beep beep’ radio signal, and lo and behold, down below was the wolf I had collared,” he says. “It was a virtual miracle in research terms.”
With the advent of more cutting-edge technology in recent years, Mech says there’s a perpetual need to keep updating the methods used in conservation to minimize the trauma they might cause to animals.
“There are still a great deal of things we don’t know about many species, and that will require even newer types of technology,” he says.
Progress is well underway. Much like how technology that was developed for human use—like radio transmission and GPS—has proved useful for research, tracking, and conservation in the past, newer consumer technology innovations are also trickling down into the study of wildlife.
Marine conservationist David Haas calls the product he developed “Fitbit for whales.” Haas developed the FaunaTag with engineer and collaborator Sam Kelly as part of his Ph.D. work, which studied how dolphins respond physiologically when they dive into the depths of the ocean. The multisensor device measures movement, acoustics, depth of travel, along with physiological factors such as heart rate, cardiac energetics, and blood oxygen level. Tags for dolphins and whales are typically dart-like, embedded in the animal’s fin or its body. But for the FaunaTag, Haas uses a suction cup to ensure that the device is as minimally intrusive as possible. “We wanted to develop noninvasive tag technology that could add to the suite of existing sensor devices, but one that could also give us some idea of what was going on with the animal’s physiology,” he tells Mongabay in a video interview.
Despite possibly being one of the very few noninvasive devices that measure multiple parameters, adapting the technology used in consumer wearables like the Apple Watch and Fitbit wasn’t an easy feat. “It’s really easy to use light to measure physiology in humans, but it’s incredibly challenging to solve that problem in dolphins and whales,” Haas says. “You are already talking about one of the hardest animals to collect physiological data on, because of their incredibly thick skin, thick blubber layers, and blood vessels.”
The parameters measured by the FaunaTag in bottlenose dolphins (Tursiops spp.) were found to be consistent with measurements made in previous studies using more invasive tags. Haas and his partner are now developing a new version of the product meant for terrestrial animals. They also continue to do more clinical validation for the products, as they await the start of manufacturing and market launch, both currently stalled by the ongoing global supply chain crisis.
While he says he’s excited at the prospect of adapting consumer technology for use in the study and conservation of wildlife, Haas also warns about the challenges that come with it. Among the many hurdles, such devices need to be built to withstand harsh wild environments—a far cry from what consumer wearables are normally subjected to. Additionally, absence of WiFi or cellular network coverage in the wild poses communication issues that aren’t usually a concern in human physiological tracking devices, at least not for a prolonged period of time.
“We spent the last four years running up against the challenges of applying human medical sensor technology to animals,” Haas says. “People should and will try it, but the challenges are non-trivial.”
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Read More »How Tagged Turtles Are Boosting Tropical Cyclone Prediction
July 22nd, 2022
Via Hakai Magazine, an article on how – in the southwest Indian Ocean – turtle-borne sensors are filling in the gaps scientists need to forecast storms:
Even with good data, it’s hard to predict tropical cyclones, which often appear with little warning and wander drunkenly around the world’s oceans. But five years ago, Olivier Bousquet, now the research director for France’s Ministry of Sustainable Development, was tasked with forecasting storms’ strengths and paths in the cyclone-infested southwest Indian Ocean. The need for better predictions was great. The area gets nine or 10 cyclones a year, and the storms are getting stronger. Tropical Cyclone Idai, in 2019, killed more than 1,000 people in Mozambique and 2014’s Gafilo killed 350 in Madagascar.
Unlike in some other parts of the ocean—like the North Atlantic, where the US National Oceanic and Atmospheric Administration flies weather drones—Bousquet had almost no data to work with. Sure, there are satellites that spy on the ocean’s surface, but those are biased around coastlines and blind in clouds, which storms have in spades. Just a handful of floating oceanographic buoys collected temperature, depth, and salinity information where Bousquet needed it. So he set out to find a new source of data.
For the past few decades, scientists have been using satellite-tagged animals to collect ocean data. For instance, in the Southern Ocean off Antarctica—a famously hostile area for humans, ships, and robot explorers—southern elephant seals have gathered most of the basic data we have on the water’s temperature and salinity.
The southwest Indian Ocean, though, didn’t have any seals Bousquet could enlist. At first, Bousquet tried seabirds, like tropicbirds and puffins, but they were too lightweight for the sensors. So he turned to sturdier helpers: loggerhead and olive ridley sea turtles.
Now here is a hardy character that can wear a 250-gram tag, travels thousands of kilometers each year, and reliably comes back to its natal beach. This homing instinct makes it easier for scientists to recover the sensor’s full suite of data, instead of just the summaries that the equipment can send to satellites over limited bandwidth while the turtle is out and about.
Sea turtles are excellent candidates for another reason. The energy that powers a tropical cyclone comes mostly from the water. To predict if a storm will intensify, you need to know what’s going on in the ocean just below the surface, from about 25 to 200 meters depth. Sea turtles spend most of their time in exactly this layer, so their intel is perfect for tropical cyclone forecasting.
Beyond that, tagged turtles could help climate studies by giving scientists a way to calibrate ocean models and satellite data. Moreover, turtles spend a lot of time foraging in giant ocean eddies—an oceanographic feature scientists would love to learn more about. A dense network of turtle data, if collected over the long term, could help scientists see how the structure of the ocean is changing over time at a very high resolution, Bousquet says.
Biologists were excited about the project, too. The temperature, depth, and location data would give them a new view of the turtles’ environment, diving behavior, and movements.
So, starting in January 2019, Bousquet teamed up with biologists at Kélonia—a sea turtle observatory on Réunion, a French island about 950 kilometers east of Madagascar—to release 15 tagged sea turtles. All had been accidentally caught by fishermen and healed in turtle rehab.
The first turtle to go out was Ilona, a loggerhead named by the fisherman who had caught her. For a few weeks, Ilona’s tag reported to the satellites 20 to 50 times per day, just as Bousquet had hoped. When Ilona got to Madagascar, though, her track stopped short. Bousquet enlisted a local NGO to investigate. They found the still-broadcasting tag … stuck to an empty shell.
Ilona had been eaten.
“We were shocked,” Bousquet says. But Ilona’s three-week journey had produced data galore.
When Bousquet and his colleagues released their initial results, suddenly everyone wanted in. The French National Centre for Space Studies, the European Union’s Interreg ocean research program, and the University of Reunion Island, among others, all jumped on board. Known as STORM (Sea Turtles for Ocean Research and Monitoring), Bousquet’s project has more than two dozen partners—and a lot more turtles. Scientists working in stormy tropics across the globe have contacted Bousquet looking to replicate the project in their areas.
Clive McMahon, a biologist at the Sydney Institute of Marine Science in Australia and a leader among those using animals to collect oceanography data, recently tagged 20 olive ridley sea turtles in a project that “is absolutely inspired by [Bousquet]’s work,” he says. STORM is “showing really clearly that turtles are able to collect these essential ocean observations to be able to predict storms.”
This year, STORM has continued to grow. Between January and March, Bousquet’s group released 80 tagged sea turtles from 10 spots around the southwest Indian Ocean. Some were rehabilitated turtles released on a schedule. Others were females caught at night on beaches after they’d laid their eggs—though “caught” might be overstating things. The procedure involves a biologist placing a box around the turtle to corral it, epoxying a tag to its back, and sampling its blood. After five minutes, the box is removed and the turtle goes on its way.
So far, storms have caught out a few turtles, Bousquet says. The turtles’ tracks show they stopped swimming, waited for the storm to pass, and moved on as before. Once, a cyclone did pass over a turtle, and then the storm did a U-turn and passed over it again. The turtle was fine.
Data from the heart of a cyclone is incredibly valuable, Bousquet says, and “every cyclone is different.” But to get the data, researchers will have to perfectly time a turtle’s release, two or three weeks before a storm blows through. They’ve missed a couple of storms by just days. “We need a little bit of luck,” Bousquet says.
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Read More »4,000 Robots Roam the Oceans, Climate in Their Crosshairs
June 20th, 2022
Via IEEE Spectrum, an article on the use of sensors to measure the tiny climate-change signals in the deep ocean:
In the puzzle of climate change, Earth’s oceans are an immense and crucial piece. The oceans act as an enormous reservoir of both heat and carbon dioxide, the most abundant greenhouse gas. But gathering accurate and sufficient data about the oceans to feed climate and weather models has been a huge technical challenge.
Over the years, though, a basic picture of ocean heating patterns has emerged. The sun’s infrared, visible-light, and ultraviolet radiation warms the oceans, with the heat absorbed particularly in Earth’s lower latitudes and in the eastern areas of the vast ocean basins. Thanks to wind-driven currents and large-scale patterns of circulation, the heat is generally driven westward and toward the poles, being lost as it escapes to the atmosphere and space.
This heat loss comes mainly from a combination of evaporation and reradiation into space. This oceanic heat movement helps make Earth habitable by smoothing out local and seasonal temperature extremes. But the transport of heat in the oceans and its eventual loss upward are affected by many factors, such as the ability of the currents and wind to mix and churn, driving heat down into the ocean. The upshot is that no model of climate change can be accurate unless it accounts for these complicating processes in a detailed way. And that’s a fiendish challenge, not least because Earth’s five great oceans occupy 140 million square miles, or 71 percent of the planet’s surface.
Providing such detail is the purpose of the Argo program, run by an international consortium involving 30 nations. The group operates a global fleet of some 4,000 undersea robotic craft scattered throughout the world’s oceans. The vessels are called “floats,” though they spend nearly all of their time underwater, diving thousands of meters while making measurements of temperature and salinity. Drifting with ocean currents, the floats surface every 10 days or so to transmit their information to data centers in Brest, France, and Monterey, Calif. The data is then made available to researchers and weather forecasters all over the world.
The Argo system, which produces more than 100,000 salinity and temperature profiles per year, is a huge improvement over traditional methods, which depended on measurements made from ships or with buoys. The remarkable technology of these floats and the systems technology that was created to operate them as a network was recognized this past May with the IEEE Corporate Innovation Award, at the 2022 Vision, Innovation, and Challenges Summit. Now, as Argo unveils an ambitious proposal to increase the number of floats to 4,700 and increase their capabilities, IEEE Spectrum spoke with Susan Wijffels, senior scientist at the Woods Hole Oceanographic Institution on Cape Cod, Mass., and cochair of the Argo steering committee.
Why do we need a vast network like Argo to help us understand how Earth’s climate is changing?
Susan Wijffels: Well, the reason is that the ocean is a key player in Earth’s climate system. So, we know that, for instance, our average climate is really, really dependent on the ocean. But actually, how the climate varies and changes, beyond about a two-to-three-week time scale, is highly controlled by the ocean. And so, in a way, you can think that the future of climate—the future of Earth—is going to be determined partly by what we do, but also by how the ocean responds.
Aren’t satellites already making these kind of measurements?
Wijffels: The satellite observing system, a wonderful constellation of satellites run by many nations, is very important. But they only measure the very, very top of the ocean. They penetrate a couple of meters at the most. Most are only really seeing what’s happening in the upper few millimeters of the ocean. And yet, the ocean itself is very deep, 5, 6 kilometers deep, around the world. And it’s what’s happening in the deep ocean that is critical, because things are changing in the ocean. It’s getting warmer, but not uniformly warm. There’s a rich structure to that warming, and that all matters for what’s going to happen in the future.
How was this sort of oceanographic data collected historically, before Argo?
Wijffels: Before Argo, the main way we had of getting subsurface information, particularly things like salinity, was to measure it from ships, which you can imagine is quite expensive. These are research vessels that are very expensive to operate, and you need to have teams of scientists aboard. They’re running very sensitive instrumentation. And they would simply prepare a package and lower it down the side into the ocean. And to do a 2,000-meter profile, it would maybe take a couple of hours. To go to the seafloor, it can take 6 hours or so.
The ships really are wonderful. We need them to measure all kinds of things. But to get the global coverage we’re talking about, it’s just prohibitive. In fact, there are not enough research vessels in the world to do this. And so, that’s why we needed to try and exploit robotics to solve this problem.
Pick a typical Argo float and tell us something about it, a day in the life of an Argo float or a week in the life. How deep is this float typically, and how often does it transmit data?
Wijffels: They spend 90 percent of their time at 1,000 meters below the surface of the ocean—an environment where it’s dark and it’s cold. A float will drift there for about nine and a half days. Then it will make itself a little bit smaller in volume, which increases its density relative to the seawater around it. That allows it to then sink down to 2,000 meters. Once there, it will halt its downward trajectory, and switch on its sensor package. Once it has collected the intended complement of data, it expands, lowering its density. As the then lighter-than-water automaton floats back up toward the surface, it takes a series of measurements in a single column. And then, once they reach the sea surface, they transmit that profile back to us via a satellite system. And we also get a location for that profile through the global positioning system satellite network. Most Argo floats at sea right now are measuring temperature and salinity at a pretty high accuracy level.
How big is a typical data transmission, and where does it go?
Wijffels: The data is not very big at all. It’s highly compressed. It’s only about 20 or 30 kilobytes, and it goes through the Iridium network now for most of the float array. That data then comes ashore from the satellite system to your national data centers. It gets encoded and checked, and then it gets sent out immediately. It gets logged onto the Internet at a global data assembly center, but it also gets sent immediately to all the operational forecasting centers in the world. So the data is shared freely, within 24 hours, with everyone that wants to get hold of it.
An animated gift of the globe with colored dots to represent the floats.This visualization shows some 3,800 of Argo’s floats scattered across the globe.ARGO PROGRAM
You have 4,000 of these floats now spread throughout the world. Is that enough to do what your scientists need to do?Wijffels: Currently, the 4,000 we have is a legacy of our first design of Argo, which was conceived in 1998. And at that time, our floats couldn’t operate in the sea-ice zones and couldn’t operate very well in enclosed seas. And so, originally, we designed the global array to be 3,000 floats; that was to kind of track what I think of as the slow background changes. These are changes happening across 1,000 kilometers in around three months—sort of the slow manifold of what’s happening to subsurface ocean temperature and salinity.
So, that’s what that design is for. But now, we have successfully piloted floats in the polar oceans and the seasonal sea-ice zones. So we know we can operate them there. And we also know now that there are some special areas like the equatorial oceans where we might need higher densities [of floats]. And so, we have a new design. And for that new design, we need to get about 4,700 operating floats into the water.
But we’re just starting now to really go to governments and ask them to provide the funds to expand the fleet. And part of the new design calls for floats to go deeper. Most of our floats in operation right now go only as deep as about 2,000 meters. But we now can build floats that can withstand the oceans’ rigors down to depths of 6,000 meters. And so, we want to build and sustain an array of about 1,200 deep-profiling floats, with an additional 1,000 of the newly built units capable of tracking the oceans by geochemistry. But this is new. These are big, new missions for the Argo infrastructure that we’re just starting to try and build up. We’ve done a lot of the piloting work; we’ve done a lot of the preparation. But now, we need to find sustained funding to implement that.
Equipment is seen inside a sphere which sits on a table.A new generation of deep-diving Argo floats can reach a depth of 6,000 meters. A spherical glass housing protects the electronics inside from the enormous pressure at that depth.MRV SYSTEMS/ARGO PROGRAM
What is the cost of a typical float?Wijffels: A typical cold float, which just measures temperature, salinity, and operates to 2,000 meters, depending on the country, costs between $20,000 and $30,000 U.S. dollars. But they each last five to seven years. And so, the cost per profile that we get, which is what really matters for us, is very low—particularly compared with other methods [of acquiring the same data].
What kind of insights can we get from tracking heat and salinity and how they’re changing across Earth’s oceans?
Wijffels: There are so many things I could talk about, so many amazing discoveries that have come from the Argo data stream. There’s more than a paper a day that comes out using Argo. And that’s probably a conservative view. But I mean, one of the most important things we need to measure is how the ocean is warming. So, as the Earth system warms, most of that extra heat is actually being trapped in the ocean. Now, it’s a good thing that that heat is taken up and sequestered by the ocean, because it makes the rate of surface temperature change slower. But as it takes up that heat, the ocean expands. So, that’s actually driving sea-level rise. The ocean is pumping heat into the polar regions, which is causing both sea-ice and ice-sheet melt. And we know it’s starting to change regional weather patterns as well. With all that in mind, tracking where that heat is, and how the ocean circulation is moving it around, is really, really important for understanding both what’s happening now to our climate system and what’s going to happen to it in the future.
What has Argo’s data told us about how ocean temperatures have changed over the past 20 years? Are there certain oceans getting warmer? Are there certain parts of oceans getting warmer and others getting colder?
Wijffels: The signal in the deep ocean is very small. It’s a fraction, a hundredth of a degree, really. But we have very high precision instruments on Argo. The warming signal came out very quickly in the Argo data sets when averaged across the global ocean. If you measure in a specific place, say a time series at a site, there’s a lot of noise there because the ocean circulation is turbulent, and it can move heat around from place to place. So, any given year, the ocean can be warm, and then it can be cool…that’s just a kind of a lateral shifting of the signal.
“We have discovered through Argo new current systems that we knew nothing about….There’s just been a revolution in our ability to make discoveries and understand how the ocean works.”
—Susan WijffelsBut when you measure globally and monitor the global average over time, the warming signal becomes very, very apparent. And so, as we’ve seen from past data—and Argo reinforces this—the oceans are warming faster at the surface than at their depths. And that’s because the ocean takes a while to draw the heat down. We see the Southern Hemisphere warming faster than the Northern Hemisphere. And there’s a lot of work that’s going on around that. The discrepancy is partly due to things like aerosol pollution in the Northern Hemisphere’s atmosphere, which actually has a cooling effect on our climate.
But some of it has to do with how the winds are changing. Which brings me to another really amazing thing about Argo: We’ve had a lot of discussion in our community about hiatuses or slowdowns of global warming. And that’s because of the surface temperature, which is the metric that a lot of people use. The oceans have a big effect on the global average surface temperature estimates because the oceans comprise the majority of Earth’s surface area. And we see that the surface temperature can peak when there’s a big El Niño–Southern Oscillation event. That’s because, in the Pacific, a whole bunch of heat from the subsurface [about 200 or 300 meters below the surface] suddenly becomes exposed to the surface. [Editor’s note: The El Niño–Southern Oscillation is a recurring, large-scale variation in sea-surface temperatures and wind patterns over the tropical eastern Pacific Ocean.]
What we see is this kind of chaotic natural phenomena, such as the El Niño–Southern Oscillation. It just transfers heat vertically in the ocean. And if you measure vertically through the El Niño or the tropical Pacific, that all cancels out. And so, the actual change in the amount of heat in the ocean doesn’t see those hiatuses that appear in surface measurements. It’s just a staircase. And we can see the clear impact of the greenhouse-gas effect in the ocean. When we measure from the surface all the way down, and we measure globally, it’s very clear.
Argo was obviously designed and established for research into climate change, but so many large scientific instruments turn out to be useful for scientific questions other than the ones they were designed for. Is that the case with Argo?
Wijffels: Absolutely. Climate change is just one of the questions Argo was designed to address. It’s really being used now to study nearly all aspects of the ocean, from ocean mixing to just mapping out what the deep circulation, the currents in the deep ocean, look like. We now have very detailed maps of the surface of the ocean from the satellites we talked about, but understanding what the currents are in the deep ocean is actually very, very difficult. This is particularly true of the slow currents, not the turbulence, which is everywhere in the ocean like it is in the atmosphere. But now, we can do that using Argo because Argo gives us a map of the sort of pressure field. And from the pressure field, we can infer the currents. We have discovered through Argo new current systems that we knew nothing about. People are using this knowledge to study the ocean eddy field and how it moves heat around the ocean.
People have also made lots of discoveries about salinity; how salinity affects ocean currents and how it is reflecting what’s happening in our atmosphere. There’s just been a revolution in our ability to make discoveries and understand how the ocean works.
As you pointed out earlier, the signal from the deep ocean is very subtle, and it’s a very small signal. So, naturally, that would prompt an engineer to ask, “How accurate are these measurements, and how do you know that they’re that accurate?”
Wijffels: So, at the inception of the program, we put a lot of resources into a really good data-management and quality-assurance system. That’s the Argo Data Management system, which broke new ground for oceanography. And so, part of that innovation is that we have, in every nation that deploys floats, expert teams that look at the data. When the data is about a year old, they look at that data, and they assess it in the context of nearby ship data, which is usually the gold standard in terms of accuracy. And so, when a float is deployed, we know the sensors are routinely calibrated. And so, if we compare a freshly calibrated float’s profile with an old one that might be six or seven years old, we can make important comparisons. What’s more, some of the satellites that Argo is designed to work with also give us ability to check whether the float sensors are working properly.
And through the history of Argo, we have had issues. But we’ve tackled them head on. We have had issues that originated in the factories producing the sensors. Sometimes, we’ve halted deployments for years while we waited for a particular problem to be fixed. Furthermore, we try and be as vigilant as we can and use whatever information we have around every float record to ensure that it makes sense. We want to make sure that there’s not a big bias, and that our measurements are accurate.
You mentioned earlier there’s a new generation of floats capable of diving to an astounding 6,000 meters. I imagine that as new technology becomes available, your scientists and engineers are looking at this and incorporating it. Tell us how advances in technology are improving your program.
Wijffels: [There are] three big, new things that we want to do with Argo and that we’ve proven we can do now through regional pilots. The first one, as you mentioned, is to go deep. And so that meant reengineering the float itself so that it could withstand and operate under really high pressure. And there are two strategies to that. One is to stay with an aluminum hull but make it thicker. Floats with that design can go to about 4,000 meters. The other strategy was to move to a glass housing. So the float goes from a metal cylinder to a glass sphere. And glass spheres have been used in ocean science for a long time because they’re extremely pressure resistant. So, glass floats can go to those really deep depths, right to the seafloor of most of the global ocean.
The game changer is a set of sensors that are sensitive and accurate enough to measure the tiny climate-change signals that we’re looking for in the deep ocean. And so that requires an extra level of care in building those sensors and a higher level of calibration. And so we’re working with sensor manufacturers to develop and prove calibration methods with tighter tolerances and ways of building these sensors with greater reliability. And as we prove that out, we go to sea on research vessels, we take the same sensors that were in our shipboard systems, and compare them with the ones that we’re deploying on the profiling floats. So, we have to go through a whole development cycle to prove that these work before we certify them for global implementation.
You mentioned batteries. Are batteries what is ultimately the limit on lifetime? I mean, I imagine you can’t recharge a battery that’s 2,000 meters down.
Wijffels: You’re absolutely right. Batteries are one of the key limitations for floats right now as regards their lifetime, and what they’re capable of. If there were a leap in battery technology, we could do a lot more with the floats. We could maybe collect data profiles faster. We could add many more extra sensors.
So, battery power and energy management Is a big, important aspect of what we do. And in fact, the way that we task the floats, it’s been a problem with particularly lithium batteries because the floats spend about 90 percent of their time sitting in the cold and not doing very much. During their drift phase, we sometimes turn them on to take some measurements. But still, they don’t do very much. They don’t use their buoyancy engines. This is the engine that changes the volume of the float.
And what we’ve learned is that these batteries can passivate. And so, we might think we’ve loaded a certain number of watts onto the float, but we never achieved the rated power level because of this passivation problem. But we’ve found different kinds of batteries that really sidestep that passivation problem. So, yes, batteries have been one thing that we’ve had to figure out so that energy is not a limiting factor in float operation.
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Read More »With Technology, Animals-Turned-Oceanographers Are Helping Biologists Track Marine Lifeg
June 1st, 2022
Via Knowable Magazine, an article on the use of technology to turn animals into oceanographers:
There’s only one word for it: indescribable. “It’s one of those awesome experiences you can’t put into words,” says fish ecologist Simon Thorrold. Thorrold is trying to explain how it feels to dive into the ocean and attach a tag to a whale shark — the most stupendous fish in the sea. “Every single time I do it, I get this huge adrenaline rush,” he says. “That’s partly about the science and the mad race to get the tags fixed. But part of it is just being human and amazed by nature and huge animals.”
Whale sharks are one of a select group of large marine animals that scientists like Thorrold, of the Woods Hole Oceanographic Institution in Massachusetts, have signed up as ocean-going research assistants. Fitted with electronic tags incorporating a suite of sensors, tracking devices and occasionally tiny cameras, they gather information where human researchers can’t. They have revealed remarkable journeys across entire oceans, and they have shown that diving deep is pretty much ubiquitous among large marine predators of all kinds.
Many regularly plunge hundreds and sometimes thousands of meters — to depths where the water can be dangerously cold and short of oxygen, there’s little or no light except for the flickers and flashes of bioluminescent organisms, and the pressure is immense, putting some animals at risk of fatal decompression sickness.
To function at such depths, deep-diving species have evolved an array of anatomical and physiological adaptations — thick, insulating blubber, for instance, or blood vessels transformed into heat-exchange systems, collapsible lungs and oxygen-storing muscles, and ultra-sensitive eyes, to name but a few. But what drove these great predators to acquire their remarkable diving skills?
For most biologists, the answer is a no-brainer: Food. Yet that’s been remarkably hard to prove. After decades of tagging studies, there’s enough circumstantial evidence to be confident that many top predators do dive deep in search of prey. But even now, only one species has been seen in action. The northern elephant seal (Mirounga angustirostris) is now something of a superstar, thanks to a pioneering series of mini-movies featuring its own snout and whiskers and a supporting cast of deep-sea fish and squid.
Food, though, might not be the deep sea’s only attraction, says Thorrold, coauthor of an article that examines the motivation of diving predators in the 2022 Annual Review of Marine Science. Dives and diving behavior vary: Some animals dive many times an hour, others sporadically. Most stick to depths between 200 and 1,000 meters, a region officially named the mesopelagic but better known as the twilight zone; others plunge far deeper. The shapes of dives hint at more than one function, too. A quick downward plunge and equally steep ascent, for instance, suggests a different purpose from a long, slow, flat-bottomed dive. “If the same individual does different types of dive at different times,” says Thorrold, “then that’s good evidence they are for different purposes.”
There is no shortage of suggestions for what those purposes might be. Deep, dimly lit waters could provide refuge from other predators; somewhere to cool an overheating body; navigational cues for those able to detect them; even a long-distance communication channel. “All these ideas are in play,” says Thorrold. “The fact we can’t rule out any of them reflects how mysterious a lot of these large pelagic animals are to us.”
Welcome to the deep-sea diner
Diving deep has evolved in nearly every type of ocean-going vertebrate. Big bony fish, such as tuna and swordfish, do it. Cartilaginous sharks and rays do it. So, too, do air-breathing animals — penguins, sea turtles, toothed whales and seals, all of which reach extraordinary depths on a single breath.Most dive as far down as the twilight zone, where the dim light from above rapidly dwindles to nothing. Some go into the blackness of the midnight zone, the bathypelagic realm between 1,000 and 4,000 meters. The current record-holder is Cuvier’s beaked whale: In 2014, one tagged whale reached 2,992 meters off the coast of Southern California. The record for a fish is held by a whale shark that reached 1,928 meters in the Gulf of Mexico in 2010.
Biologists of times past would never have dreamt that deep waters would have much to offer a top predator. In the 19th century, naturalists believed that little lived deeper than 500 meters or so — but in the 1940s, Navy sonar operators discovered the deep scattering layer, a zone where their sonar bounced off multitudes of mesopelagic organisms. This food-packed layer moved up and down as fish and tiny invertebrates migrated toward the surface to feed at night and retreated to the relative safety of deep water during the day.
The ocean’s twilight zone turned out to be an unexpectedly well-stocked larder, filled with weird and wonderful gelatinous creatures, muscular squid, the ubiquitous and highly nutritious lanternfish and the spiny-toothed bristlemouth, reckoned to be the world’s most abundant vertebrate. In 1980, fisheries scientists estimated the global biomass of mesopelagic fish at a billion metric tons, based on surveys with nets. In 2014, a study based on acoustic surveys put the figure seven to 10 times higher.
As yet, there is no global estimate of the life in the chill, black depths of the midnight zone, but a study in the waters over the Mid-Atlantic Ridge found an even greater mass of potential prey there. “Diving to forage makes sense if deep water is where the biomass is,” says Thorrold.
Until very recently, though, all the supporting evidence for foraging was circumstantial. Mesopelagic fish, squid and crustaceans turned up in the stomachs of tuna, swordfish and blue sharks, while sperm whale stomachs contained the indigestible beaks of deep-sea squid, including the giant squid Architeuthis. Tagging studies consistently put predator and prey in the same place at the same time. They’ve shown that large fish and mammals regularly and repeatedly dive into the deep scattering layer, and often dive deeper during the day when potential prey has migrated further into the gloom. Some tagged tuna and swordfish track precisely the daily migration of potential prey.
With the development of increasingly sophisticated tags, biologists are building an ever more detailed picture of what these animals are doing in the depths. Attached to fins and flippers, heads and jaws, they collect and store a wide range of data over many months. Tags that include sensors for pressure, temperature and light have enabled researchers to reconstruct movements through the water and the depth and profile of dives. The past few years have seen the emergence of innovative extras — accelerometers that log the twisting and turning of a head, sensors that detect the movement of jaws, sound-detecting hydrophones, even a smart video camera that shoots only moments worth recording.
Getting these tags onto top predators is hugely challenging. “Whale sharks are rare and elusive, but we’ve now gotten a good number of tags on them,” says Thorrold. Fearsome sharks like the great white are challenging for a different reason. Free diving is not an option, and if you want to tag the creature’s dorsal fin, you need a ship with a hydraulic platform to lift the shark aboard, where the operation can be carried out safely.
Swordfish are particularly tricky to tag. They are hard to find, unpredictable and dangerous, as Thorrold’s coauthor Peter Gaube, an oceanographer at the University of Washington, can testify. “When you do catch one, you have to hold it alongside the boat and try to fix the tags while it tries to whack you or bash a hole in the boat with that razor-sharp sword.”
The devil’s in the details
Some of the best evidence of foraging has come from unexpected quarters — such as the Chilean devil ray (Mobula tarapacana), a huge but mysterious fish with a “wingspan” of almost4 meters. Most sightings of Chilean devil rays come from surface waters, where they often seem to bask in the sun, a habit that led to the assumption that they prefer life nearer the surface.Curious to know more about them, Thorrold and colleagues made two tagging expeditions to the Azores, where large numbers of devil rays gather around the Princess Alice seamount for a few months each year. In 2011, the team tagged four rays; in 2012, they tagged 11 more. The tags logged the rays’ movements for up to five months before transmitting their data back to Woods Hole.
The results were staggering: Not only did the devil rays travel thousands of kilometers at a cracking pace, they frequently plunged 1,000 meters and more. The deepest recorded dive was 1,896 meters. The sun-soaking, surface-dwelling rays are anything but: They are among the deepest diving fish in the sea, and everything points to food as the attraction.
Most of the devil ray dives had an unusual stepwise profile. “They dive deep, then level for a bit, come up a bit and level again, and so on,” says Thorrold. “If you look at sonar, it seems they stop off where there are thin but dense layers of prey. We haven’t been able to see what they are doing, but this is strong evidence that they are foraging.”
That would explain why Chilean devil rays have a network of well-developed blood vessels in their brain cavity, much like that found in some deep-diving sharks, where it functions as a heat-exchange system to prevent the brain from growing too cold. Biologists had always wondered why a fish that lives in the sunlit upper waters of the ocean would need one. “This is more evidence that devil rays forage at depth and so need to keep their brain and sensory systems active in the cold,” says Thorrold.
As for basking in the sun — that, Thorrold suggests, is to warm up before and after deep dives.
Like devil rays, tag-toting sharks have been providing intriguing glimpses of behavior that lends more weight to the idea that they hunt in deep waters. Most of what we know of sharks comes from studies in coastal waters — yet many migrate vast distances across the open ocean. Away from the seal-studded coasts, prey becomes patchy and thinly spread. So how do big sharks get enough to eat?
Recent research suggests that some sharks have a smart strategy to gain access to the ocean’s biggest buffet. Data from two great white sharks and 15 blue sharks as they traveled the North Atlantic showed that they take advantage of eddies, swirling masses of water that break away from the Gulf Stream. Eddies that spin off the northern edge of the Gulf Stream trap warmer water from the south; eddies formed from the southern edge carry cool water southward. Both white and blue sharks showed a marked preference for warm-hearted eddies.
These warm eddies contain a higher density of mesopelagic prey, acoustic surveys have shown. And with anomalously warm water extending hundreds of meters, sharks can forage much deeper and for longer. “Warm eddies can provide sharks access to deeper food sources that would otherwise be inaccessible,” says Gaube, a coauthor of the research.
Sound and vision
The nearest thing to proof that marine predators evolved extreme diving skills to exploit a rich but otherwise inaccessible source of food is coming from animals wearing tags with extra bells and whistles.In the case of the short-finned pilot whale (Globicephala macrorhynchus), that meant a sound recorder. Pilot whales emit a series of clicks while they hunt, listening for echoes bouncing off prey. As they close in on a target, the clicks come so thick and fast they merge to a buzz. Natacha Aguilar de Soto, a marine biologist at the University of La Laguna, Tenerife, in Spain’s Canary Islands, decided to eavesdrop on local pilot whales during their dives and fitted 23 of them with sound-recording tags.
The tagged whales dived deep, reaching a maximum of 1,019 meters, clicking as they went. Just before the deepest point of a dive, the clicks turned to buzzes — a sign that a whale was about to launch its attack. On the occasions when a whale dived very deep, it made a final, high-speed dash before it buzzed, which Aguilar de Soto interprets as an extra push in pursuit of fleeing prey, something large enough to be worth drawing on a rapidly dwindling oxygen supply, such as a Grimaldi scaled squid (a meter long plus tentacles) or even perhaps a giant squid.
Hearing the sound of the hunt is convincing, but it’s still not proof. “We need to see what these predators are doing,” says Thorrold. For now, biologists must content themselves with the short snippets of film shot by the northern elephant seal.
Female northern elephant seals make good research assistants, especially those belonging to the colony in Año Nuevo State Park, just north of Santa Cruz. Biologists from the University of California, Santa Cruz (UCSC), have been running a research program there for more than half a century. The Año Nuevo elephant seals have the advantage of being accessible: Like others of their kind, they haul out on land in the winter to pup and mate, and again in the spring or summer to molt.
In between, the males remain in coastal waters, but the females migrate thousands of kilometers across the Pacific and back again, diving continuously as they travel. It’s a lot simpler to fit tags and retrieve them later than it is for, say, a great white shark, and there are expert elephant seal wranglers on hand to help. “It can be dangerous, though,” says Japanese biologist Taiki Adachi, who has worked with the seals for more than a decade and is currently based at UCSC. “They are very big and aggressive, and are especially scary in the breeding season, when the mothers have to protect their pups and males are defending their harem.”
Adachi recently reported that migrating female elephant seals dive almost continuously for 20 or more hours each day. “They mostly dive to 400 to 600 meters, the depth where small fish — especially oil-rich lanternfish — are very abundant,” he says. Sometimes they go far deeper, consistently diving 800 meters or more: The maximum recorded for this species is 1,735 meters.
At Japan’s National Institute of Polar Research, Adachi’s colleague Yasuhiko Naito developed an ingenious jaw-motion recorder that logs a seal’s attempts to snatch prey from the water. Fitted to the seal’s lower jaw, the device logged 1,000 to 2,000 attempts a day. The clincher, though, came from another of Naito’s innovations: a smart video tag that is attached to the seal’s jaw or head. The camera and lights are triggered by a combination of depth and the movements characteristic of a strike, a system that makes the most of the tag’s limited battery power.
The first elephant seal selfies, taken by one individual seal and published in 2017, showed it trying to catch fish some 800 meters down. The 21 fuzzy images showed parts of what were later identified as large, deep-sea ragfish. With the help of more camera-carrying seals, the team eventually had 48 hours of footage from 240 meters to more than 1,000 meters deep and capturing almost 700 attacks. The quality was good enough to identify not just the type of prey but in some cases the species. They included the little lanternfish, ragfish and a type of hake, plus half a dozen different squid, including cockeyed squid and glass squid.
A place of greater safety
Aside from diving for food, there is evidence that dives, especially more extreme ones, serve other purposes. Escaping from more formidable predators is a definite contender.Take yellowfin tuna (Thunnus albacares), which spend most of their time in the ocean’s upper 200 meters. In 2020, fisheries biologist Tim Lam, from the University of Massachusetts Boston, reported that six of 17 tuna he tagged in the waters off Hawaii appeared to have had a run-in with a predator. Four dived deep — three of them to around 1,000 meters — and then lost their tags, possibly during frantic maneuvers as they tried to escape, Lam suggests. A fifth tuna plunged suddenly from 134 meters to 1,592 meters — a dash interpreted as a possible attempt to outrun an enemy. When it returned to the surface, it appeared to have the jitters, spending the whole day near the surface before resuming normal activity.
And, then there was the one that didn’t get away: Data from its tag showed that it reached a depth of 326 meters and then everything went dark and the temperature rose, probably because it was inside the stomach of a false killer whale or short-finned pilot whale.
Elephant seals also seem to take advantage of the dimly lit depths to avoid their enemies. The commonest cause of death for these seals is thought to be predation by sharks or killer whales while at sea, says physiological ecologist Roxanne Beltran, who works on the Año Nuevo elephant seal program. “But we see lots of seals come to shore with fresh or healing shark bites, so clearly it’s possible to evade their predators.”
Biologists studying the northern elephant seals at Año Nuevo State Park in California fit and retrieve tags when the animals haul out on land after their long-distance migrations. Here, they are looking for a tagged female that has just returned.
One way is to head downward. An early hint that the seals do just that came from a test run of a novel tag more than a decade ago. As part of research on the impacts of underwater noise, bioacoustician Selene Fregosi of Oregon State University fitted young elephant seals at Año Nuevo with a prototype tag that played back recorded sounds. The idea was to expose seals to short bursts of various noises and see how they react. The playlist included echolocating clicks and whistles of killer whales and sperm whales; both sent elephant seals into steep dives. If a seal was already diving, it accelerated; if it was on its return to the surface, it turned tail and dived deeper, in one case almost doubling its original depth.
Last year, Beltran and colleagues reported that elephant seals don’t just flee into the darkness, they also rest there. Elephant seals are more likely to be killed in the brightly lit upper ocean, where sharks and killer whales are common. They have time only for short breaks from foraging, drifting effortlessly for 10 to 20 minutes at a time. Their preference, Beltran discovered, is to rest several hundred meters below the surface. And the fatter and fitter they become, the deeper they go in search of greater safety.
What, then, of other suggested reasons for diving into the deep?
Navigation looks highly likely. Almost all large marine predators migrate long distances at some point in their lives. Some — including sharks and turtles — are known to be capable of detecting cues provided by Earth’s magnetic field, sensing gradients in magnetic intensity and anomalies created by geological features such as seamounts. “Animals that can sense these cues might dive deep, where the signals are stronger,” says Thorrold. Leatherback turtles make extreme dives only during long migrations, suggesting they might be checking they are on the right route. Hammerhead sharks in the Gulf of California are thought to find their way to and from seamounts by sensing the local magnetic “landscape.”
There’s a single example of a species that appears to dive to cool off. Atlantic bluefin tuna spend months each year in cold temperate waters and have evolved a highly effective way to maintain their body heat — but they spawn in the subtropical Gulf of Mexico, where that’s a handicap. In an apparent strategy to avoid overheating, the tuna dive below 500 meters as they enter and leave the Gulf and stay below 200 meters while they spawn.
That leaves the possibility that the deep sea is a good place to talk. There’s a zone that stretches from a depth of a few hundred meters to more than a thousand, where sound travels further, making it ideal for long-distance communication. When blue and fin whales are in the zone, they can be heard an estimated 1,700 kilometers away, though no one knows if they go there for that specific purpose.
“There’s so much we don’t know, even with the technology that’s become available in the past 20 years,” says Thorrold. The future tech wish list is long. Thorrold and his colleagues are testing a prototype tag that can locate an animal’s position in the water column with much greater accuracy. They’d love to have tags that send back only relevant data from the vast quantities recorded over many months at sea.
Top of the list, though, are small, smart cameras. If elephant seals can make such great movies, why couldn’t other top predators? “We need better fish-cams that are small enough to mount on tuna, sharks and swordfish,” says Thorrold. “They need to be miniaturized but high-resolution, able to operate in low light levels and log data during the long periods they are traveling the open ocean.”
In short, seeing is believing. Besides, who wouldn’t want to watch a great white shark’s home movies?
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Read More »Using Data From Space To Develop A Global View Of Animal Movements
March 21st, 2022
Via Yale News, an article on how data from space unveil a global view of animals on the move:
A global team of researchers, including Yale scientists, is using advanced tagging to track the movement of individual animals across the world, an ambitious research project that is opening a new frontier in efforts to monitor biodiversity change and pinpoint areas for conservation intervention.
For the project, individual animals from 15 species worldwide were tagged with lightweight sensors that transmit data to the International Space Station, which then transmits the information to a single system for integration and interpretation. Since late 2021, the new technology has captured the movements of hundreds of small animals, such as blackbirds, artic terns, and even bats. Eventually they hope to track many species of reptiles, mammals, and insects.
The first findings are described March 8 in the journal Trends in Ecology and Evolution.
“For the first time, we are able to have a finger on the pulse of life worldwide,” said Walter Jetz, lead author of the study, co-director of the Max Planck-Yale Center for Biodiversity Movement and Global Change (MPYC), and a professor of ecology and evolutionary biology and of the environment at Yale. “This now operational technology blazes the trail for a biological earth observation with animal sensors.”
Given the low cost and small tag size researchers hope to scale the effort to thousands of species and deliver data about animal lives globally in real time, said Jetz.
The project is called ICARUS or International Cooperation for Animal Research Using Space, a collaboration of international scientists led by the Max Planck Society.
The effort relies upon trained volunteers to place the miniature sensors, which weigh less than one-tenth of an ounce, on individual animals. The sensors not only record GPS data but can also supply other information on conditions experienced by animals, such as temperature.
Data from the sensors are collected from the International Space Station and then transmitted to computers on the ground. While most of the species tagged so far are birds, future tagging could include many species of land animals, researchers say.
“Rather than globe-orbiting sensors capturing images of the planet’s surface for subsequent interpretation, animals, through countless individual movement decisions, seek out their preferred conditions, sensing the quality and health of ecosystems in real time,” said Martin Wikelski, co-director of MPYC, research director at the Max Planck Institute for Animal Behavior in Germany, and originator of ICARUS.
For instance, scientists will not only be able to identify areas essential for survival of the animals, but identify areas where biodiversity may be threatened by human encroachment or poaching when anticipated migration routes are blocked.
With the technology now in place, the Max Planck-Yale Center is currently raising funds to purchase more sensors, which cost about $300 each, support researchers worldwide to use and scale up the system, train volunteers, and integrate information sharing platforms. The group is also negotiating with NASA and the German space agencies to place new data collection devices on satellites.
“The dream is an ongoing cohort of say 100,000 animal sentinels that help us humans measure, understand, and mitigate our changes to this planet,” Jetz said.
Movements across space and environments, home ranges and migration corridors from these new data can be explored at the website https://animallives.org, an initiative of the international Max Planck-Yale Center for Biodiversity Movement and Global Change (MPYC).
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