THE CREATION OF MICROPLASTICS

Researchers discover faster, more energy-efficient way to manufacture an industrially important chemical

Zirconium combined with silicon nitride enhances the conversion of propane — present in natural gas — needed to create in-demand plastic, polypropylene

Peer-Reviewed Publication

DOE/ARGONNE NATIONAL LABORATORY

 

IMAGE: 

ZIRCONIUM (LARGER BURNT ORANGE ATOM), COMBINED WITH SILICON NITRIDE (BLUE AND GRAY ATOMS), ENHANCES THE TRANSFORMATION OF PROPANE INTO PROPYLENE IN A WAY THAT'S FASTER AND USES LESS ENERGY THAN MORE TRADITIONAL MEANS.

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CREDIT: (IMAGE BY DAVID KAPHAN, MAX DELFERRO AND YU LIM KIM/ARGONNE NATIONAL LABORATORY.)

Polypropylene is a common type of plastic found in many essential products used today, such as food containers and medical devices. Because polypropylene is so popular, demand is surging for a chemical used to make it. That chemical, propylene, can be produced from propane. Propane is a natural gas commonly used in barbeque grills.

Scientists from the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Ames National Laboratory report a faster, more energy-efficient way to manufacture propylene than the process currently used.

Converting propane into propylene typically involves a metal catalyst like chromium or platinum on a support material, such as aluminum oxide or silicon dioxide. The catalyst speeds up the reaction. However, it also necessitates high operating temperatures and energy use.

“One person cannot do everything. This is really a team effort, and everyone brought their expertise to the table to achieve this goal.” — Max Delferro, Argonne chemist

In a collaborative project, scientists from Argonne and Ames found that zirconium combined with silicon nitride enhances the catalytic conversion of propane gas to propylene. It does so in a way that is faster-reacting and less toxic and uses less energy than other nonprecious metals, like chromium. It is also less expensive than precious metal catalysts like platinum.

This discovery also reveals a way to reduce the temperature of the catalytic process. In turn, this reduces the amount of carbon dioxide released. Carbon dioxide accounts for almost 80% of greenhouse gas emissions in the United States.

Additionally, this research gives a glimpse into the reactivity achievable with other low-cost metals in the catalytic conversion of propane into propylene.

For some time, Argonne chemists David Kaphan and Max Delferro have been systematically studying how nontraditional surfaces influence and promote catalysis.

As lead researchers on this study, they wanted to understand how a nontraditional metal catalyst on a nontraditional type of support compares with traditionally used materials during the catalytic conversion of propane.

Catalyst support materials typically have high surface areas and help to distribute catalysts. They can also play an important role in promoting catalysis, as shown in this study.

The research team found that a zirconium catalyst on a silicon nitride support yielded significantly more active catalysis for the conversion of propane into propylene. Conversely, this was not the case with the silica support.

They also found that the silicon nitride support enabled catalysis in a way that’s faster and more energy efficient than with traditional metals on silica. As a catalyst support, silicon nitride can enhance chemical reactions on the surface of metals relative to more traditionally used oxides.

The scientists achieved catalytic conversion of propane at a temperature of 842 degrees F. This is slightly lower than the 1,022 degrees F typically required for catalysis using traditional materials.

Furthermore, when run at the same temperature as traditional catalysts for this transformation, the reaction rates were significantly faster than similar materials with oxide supports.

This discovery also offers proof that this concept can be generalized for other important reactions.

“This provides a window into nitride-supported metal reactivity. We see promise with the use of other transition metals where we can leverage this difference in the local environment of the nitride surface to enhance catalysis,” Kaphan said.

This research benefited from Argonne’s Advanced Photon Source (APS), a DOE Office of Science user facility. At beamline 10-BM, researchers used X-ray absorption spectroscopy to understand how the zirconium catalyst interaction with the nitride material differs from the oxide material.

Argonne researchers also collaborated with Frédéric Perras, a scientist at Ames National Laboratory, to gain a better understanding of the structure of the zirconium/silicon nitride catalyst. He used a dynamic nuclear polarization-enhanced nuclear magnetic resonance technique to analyze how silicon nitride reacts with metal sites.

“The composition on the surface of silicon nitride is largely unknown, which is what I found most exciting about this work,” said Perras, who is also an adjunct associate professor at Iowa State University.

The combination of material characterization techniques available at Argonne and Ames and the expertise of the people who worked on this paper is what contributed to the success of this experiment, according to Delferro.

“One person cannot do everything. This is really a team effort, and everyone brought their expertise to the table to achieve this goal,” he said.

A paper on the study was published in the Journal of the American Chemical Society. In addition to Delferro, Kaphan and Perras, authors include Joshua DeMuth, Yu Lim Kim, Jacklyn Hall, Zoha Syed, Kaixi Deng, Magali Ferrandon, A. Jeremy Kropf and Liu Cong.

Support for the research came from DOE’s Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, Catalysis Science program.

About the Advanced Photon Source

The U. S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS.

This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology by conducting leading-edge basic and applied research in virtually every scientific discipline. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.

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JOURNAL

Journal of the American Chemical Society

DOI

10.1021/jacs.4c02776 

ARTICLE TITLE

Silicon Nitride Surface Enabled Propane Dehydrogenation Catalyzed by Supported Organozirconium

 

Butterflies accumulate enough static electricity to attract pollen without contact, new research finds

UNIVERSITY OF BRISTOL

 

IMAGE: 

HAWKMOTH

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CREDIT: SAM ENGLAND

Butterflies and moths collect so much static electricity whilst in flight, that pollen grains from flowers can be pulled by static electricity across air gaps of several millimetres or centimetres.

The finding, published today in the Journal of the Royal Society Interface, suggests that this likely increases their efficiency and effectiveness as pollinators.

The University of Bristol team also observed that the amount of static electricity carried by butterflies and moths varies between different species, and that these variations correlate with differences in their ecology, such as whether they visit flowers, are from a tropical environment, or fly during the day or night. This is the first evidence to suggest that the amount of static electricity an animal accumulates is a trait that can be adaptive, and thus evolution can act upon it by natural selection.

Lead author Dr Sam England from Bristol’s School of Biological Sciences, explained: “We already knew that many species of animal accumulate static electricity as they fly, most likely through friction with the air. There had also been suggestions that this static electricity might improve the ability of flower-visiting animals, like bees and hummingbirds, to pollinate, by attracting pollen using electrostatic attraction.

“However, it wasn’t known whether this idea applied to the wider array of equally important pollinators, such as butterflies and moths. So, we set out to test this idea, and see if butterflies and moths also accumulate charge, and if so, whether this charge is enough to attract pollen from flowers onto their bodies.”

Their study involved 269 butterflies and moths across 11 different species, native to five different continents and inhabiting multiple different ecological niches. They were then then able to compare between them and see if these ecological factors correlated with their charge, establishing if static charging is a trait that evolution can act upon.

Dr England added: “A clearer picture is developing of how the influence of static electricity in pollination may be very powerful and widespread.

“By establishing electrostatic charging as a trait upon which evolution can act, it opens up a great deal of questions about how and why natural selection might lead to animals benefiting or suffering from the amount of static electricity that they accumulate.”

In terms of practical applications, this study opens the door to the possibility for technologies to artificially increase the electrostatic charges or pollinators or pollen, in order to improve pollination rates in natural and agricultural settings.

Dr England concluded: “We’ve discovered that butterflies and moths accumulate so much static electricity when flying, that pollen is literally pulled through the air towards them as they approach a flower.

“This means that they don’t even need to touch flowers in order to pollinate them, making them very good at their jobs as pollinators, and highlighting just how important they might be to the functioning of our flowery ecosystems.

“For me personally, I would love to do a wider survey of as many different species of animal as possible, see how much static electricity they accumulate, and then look for any correlations with their ecology and lifestyle. Then we can really begin to understand how evolution and static electricity interact!”

CAPTION

Peacock butterfly

CREDIT

Sam England

Paper:

‘Electrostatic pollination by butterflies and moths’ by Sam J. England and Daniel Robert in Journal of the Royal Society Interface.

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JOURNAL

Journal of The Royal Society Interface

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Electrostatic pollination by butterflies and moths

ARTICLE PUBLICATION DATE

24-Jul-2024

 

Mixed approach to reforestation better than planting or regeneration alone

DUKE UNIVERSITY

 

IMAGE: 

TREE NURSERY IN MADHESH PROVINCE, NEPAL

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CREDIT: JEFF VINCENT

DURHAM, NC – Reforestation in low- and middle-income countries can remove up to 10 times more carbon dioxide from the atmosphere at lower cost than previously estimated, making this a potentially more important option to fight climate change, according to a study in Nature Climate Change.  

Reforestation regrows trees on degraded lands where human activities removed original forests. Most current reforestation programs focus on tree planting alone, but the study estimates that nearly half of all suitable reforestation locations would be more effective at sequestering carbon if forests were allowed to grow back naturally.

“Wood markets are one key to large-scale reforestation,” said co-author Jeff Vincent, professor of forest economics and management at Duke University’s Nicholas School of the Environment. “In more than half the areas we studied, timber plantations sequester carbon at a lower cost than forests that grow back naturally.” 

Carbon sequestration captures and stores carbon dioxide from the atmosphere, which reduces greenhouse gases and helps combat climate change. It can be done naturally by plants or through technology. In countries that are among the most affected by deforestation, but least resourced to reforest, determining how to allocate scarce funding to sequester the most carbon can be a challenge.  

“A mix of planted and naturally regenerated forests is often the best way to balance society’s many demands on forests,” said Vincent. “That’s what we find for the case of carbon.” 

"This more biodiverse method of reforestation is vastly underutilized,” said Jonah Busch, lead author of the study, who conducted the research as a Climate Economics Fellow at Conservation International. 

Using a mix of the two reforestation methods – replanting the forest in some locations, and letting nature take its course in others - could sequester more carbon than using only tree planting or natural regeneration alone, the researchers calculate. 

Carbon payments made by companies and other organizations looking to offset, or cancel out, their own greenhouse gas emissions are one way to incentivize reforestation. 

“Carbon payments can provide a sufficient reforestation incentive on their own in some places,” said Vincent. “While the net cost of carbon sequestration can be reduced in other places by earning income from sustainable wood harvests.” 

That net cost is the total expense involved in capturing and storing carbon dioxide from the atmosphere, minus any savings or benefits gained from the process. If a project generates income from timber sales or wood products, for example, that brings down its net cost.  

Which method is more cost-effective, natural growth vs. planting trees, in a given location depends on multiple factors. Variables include forest growth rates; proximity to natural seed sources for natural regeneration and wood-processing mills for plantations; the value of land in its current use, typically some form of agriculture; the costs of implementing each method, typically much lower for natural regeneration; and, for plantations, the frequency of timber harvests and the duration of carbon storage in wood products. 

The research team modeled these factors for the two reforestation methods. The result is a world map showing which reforestation method is more cost-effective by location. 

“We hope our map will help governments, companies and other organizations use their forest restoration budgets more efficiently,” said Vincent.  

CITATION: Cost-effectiveness of natural forest regeneration and plantations for climate mitigation,” Jonah Busch, Jacob J. Bukoski, Susan C. Cook-Patton, Bronson Griscom, David Kaczan, Matthew D. Potts, Yuanyuan Yi, Jeffrey R. Vincent. Nature Climate Change, July 24,2024. 

 

 

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JOURNAL

Nature Climate Change

DOI

10.1038/s41558-024-02068-1 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Cost-effectiveness of natural forest regeneration and plantations for climate mitigation

ARTICLE PUBLICATION DATE

24-Jul-2024

 WAIT, WHAT?!

Komodo dragons have iron-coated teeth to rip apart their prey

AND REALLY BAD BREATH

KING'S COLLEGE LONDON

Scientists have discovered that the serrated edges of Komodo dragons’ teeth are tipped with iron.

Led by researchers from King’s College London, the study gives new insight into how Komodo dragons keep their teeth razor-sharp and may provide clues to how dinosaurs like Tyrannosaurus rex killed and ate their prey.

Native to Indonesia, Komodo dragons are the largest living species of monitor lizard, averaging around 80kg. Deadly predators, Komodos have sharp, curved teeth similar to many carnivorous dinosaurs. They eat almost any kind of meat, from smaller reptiles and birds to deer, horses or water buffalo, pulling and tearing at their prey to rip flesh apart.

The researchers discovered that many reptiles have some iron in their teeth, but Komodo dragons have concentrated the iron along the cutting edges and tips of their teeth, staining them orange. Crocodiles and other monitor lizards, by comparison, have so little that the iron is often invisible.

To understand the chemical and structural make-up of Komodo dragon’s teeth, scientists scoured museums for skulls and teeth of Komodo dragons and studied the teeth of Ganas, the 15-year-old Komodo dragon who had lived at ZSL conservation zoo, London Zoo.

Through advanced imaging and chemical analysis, the team was able to observe that the iron in Komodo dragons' enamel is concentrated into a thin coating on top of their tooth serrations and tips. This protective layer keeps the serrated edges of their teeth sharp and ready to be used at a moment’s notice.

The research, published today in Nature Ecology & Evolution, leads to new questions and avenues for research into how extinct species such as dinosaurs lived and ate.

Dr Aaron LeBlanc, lecturer in Dental Biosciences at King’s College London and the study's lead author said: “Komodo dragons have curved, serrated teeth to rip and tear their prey just like those of meat-eating dinosaurs. We want to use this similarity to learn more about how carnivorous dinosaurs might have ate and if they used iron in their teeth the same way as the Komodo dragon.

“Unfortunately, using the technology we have at the moment, we can’t see whether fossilised dinosaur teeth had high levels of iron or not. We think that the chemical changes which take place during the fossilisation process obscure how much iron was present to start with.

“What we did find, though, was that larger meat-eating dinosaurs, like tyrannosaurs, did change the structure of the enamel itself on the cutting edges of their teeth. So, while Komodo dragons have altered the chemistry of their teeth, some dinosaurs altered the structure of their dental enamel to maintain a sharp cutting edge.

“With further analysis of the Komodo teeth we may be able to find other markers in the iron coating that aren’t changed during fossilisation. With markers like that we would know with certainty whether dinosaurs also had iron-coated teeth and have a greater understanding of these ferocious predators.”

Dr Benjamin Tapley, Curator of Reptiles and Amphibians at ZSL and co-author on the study said: “As the world’s largest lizards, Komodo dragons are inarguably impressive animals. Having worked with them for 12 years at London Zoo, I continue to be fascinated by them and these findings further emphasise just how incredible they are.

“Komodo dragons are sadly endangered, so in addition to strengthening our understanding of how iconic dinosaurs might have lived, this discovery also helps us build a deeper understanding of these amazing reptiles as we work to protect them.”

Iron-coated Komodo dragon teeth and the complex dental enamel of carnivorous reptiles (DOI:  10.1038/s41559-024-02477-7) was published in Nature Ecology & Evolution.

ENDS

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JOURNAL

Nature Ecology & Evolution

DOI

10.1038/s41559-024-02477-7 

ARTICLE TITLE

Iron-coated Komodo dragon teeth and the complex dental enamel of carnivorous reptiles

 

Researchers record first-ever images and data of a shark experiencing a boat strike

OREGON STATE UNIVERSITY

 

IMAGE: 

A 7-METER BASKING SHARK FEEDING NEAR THE SURFACE AFTER IT WAS TAGGED BY RESEARCHERS. 

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CREDIT: BIG FISH LAB, OREGON STATE UNIVERSITY.

NEWPORT, Ore. – Hours after tagging an endangered basking shark off the coast of Ireland in April, researchers captured what they believe is the first ever video of a shark or any large marine animal being struck by a boat.

The data, collected by an activity measurement device similar to a FitBit and a connected camera, provided scientists a unique opportunity to learn more about the impact of vessel strikes on large marine animals, which is a rising concern around the globe, said Taylor Chapple, a shark researcher at Oregon State University’s Hatfield Marine Science Center and lead author of the study.

“This is the first ever direct observation of a ship strike on any marine megafauna that we’re aware of,” Chapple said. “The shark was struck while feeding on the surface of the water and it immediately swam to the seafloor into deeper, offshore waters, a stark contrast to its behavior prior to the strike.”

“Our findings demonstrate the risk and impact of vessel strikes and the need for measures to reduce this risk.”

Researchers do not know whether the shark, a female about 7 meters long, eventually recovered from the strike. The tag was designed to release itself from the animal at a pre-determined time. About seven hours after the strike, the tag was released and later retrieved by researchers. The data showed the shark never resumed feeding or other normal behavior while it was being monitored, Chapple said.

The findings were just published in the journal Frontiers in Marine Science.

Basking sharks are the second largest known fish, frequently reaching more than 8 meters in length. They are listed as globally endangered by the International Union for Conservation of Nature, and Ireland is one of the only known locations worldwide where basking sharks continue to aggregate in large numbers.

They filter feed at the water’s surface, similar to some whales, which makes them more susceptible to boat strikes. But unlike the whales, basking sharks often sink when killed, making it hard to gauge mortality rates, said Chapple, assistant professor in the Coastal Oregon Marine Experiment Station and Department of Fisheries, Wildlife, and Conservation Sciences in OSU’s College of Agricultural Sciences.

Basking sharks in Ireland were protected under the country’s Wildlife Act in 2022. Earlier this year, the Irish government announced the establishment of the nation’s first National Marine Park, protecting 70,000 acres of land and sea on the coast of County Kerry where basking sharks frequent seasonally for feeding and potentially mating.

Shortly after the park’s establishment, the researchers were conducting a previously planned study in the park boundaries to learn more about basking shark foraging behavior and how such behavior corresponds to environmental factors. As part of their research, they tagged the basking shark with a camera and activity monitor system while it was feeding.

After following the shark at a safe distance for a few hours, the researchers departed the area for the day. The tag was designed to record autonomously until its scheduled release, at which time the researchers located it and recovered the data.

Data from the tag revealed that for several hours following the tagging and tracking, the shark spent most of its time on the surface, continuing its normal feeding behavior, with an occasional dive. Then the shark attempted to make a quick, evasive movement, which was followed by the keel of a boat cutting across its back, just behind its dorsal fin. The shark tumbled through the water and immediately increased the frequency of its tailbeat as it headed to the seafloor.

Video from the camera showed visible damage to the shark’s skin, paint marks and a red abrasion but no apparent bleeding or open wound. Vessel strikes are not always immediately lethal, but even non-lethal injuries can have short- and long-term consequences for the affected animal, the researchers noted.

“The fact that a shark we fitted our ‘Fitbit’ to was struck in this area within a few hours underlines just how vulnerable these animals are to boats and highlights the need for greater education in how to mitigate against such strikes,” said co-author Nicholas Payne, an assistant professor at Trinity College Dublin’s School of Natural Sciences. “Basking sharks filter feed at the surface, like some whales, and this behavior makes them similarly susceptible to strikes.”

The incident highlights the need for additional research on the interactions between water users and basking sharks in the National Marine Park and other hotspots along the Irish coastline, said co-author Alexandra McInturf, a research associate in Chapple’s Big Fish Lab at OSU and co-coordinator of the Irish Basking Shark Group.

“This research raises additional questions about whether and how often the sharks are actually occupying such habitats when they are not clearly visible at the surface,” McInturf said. “Given that Ireland is one of the only locations globally where basking sharks are still observed persistently, addressing such questions will be critical to informing not only our ecological understanding of the basking shark, but also the conservation of this globally endangered species.” 

Additional coauthors are David Cade and Jeremy Goldbogen of the Hopkins Marine Station at Stanford University; and Nick Massett of the Irish Whale and Dolphin Group in County Kerry, Ireland.

This image depicts the keel of a boat striking a basking shark. 

This image shows paint and an abrasion on the back of a basking shark that ha been struck by a boat. 

CREDIT

Big Fish Lab, Oregon State University.

JOURNAL

Frontiers in Marine Science

DOI

10.3389/fmars.2024.1430961 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Behavioral response of megafauna to boat collision measured via animal-borne camera and IMU

ARTICLE PUBLICATION DATE

24-Jul-2024

URI partners on study that tracked whale shark for record-breaking four years

Rio Lady's movements, migration allow researchers to 'investigate whale sharks at a unprecedented degree'

UNIVERSITY OF RHODE ISLAND

KINGSTON, R.I. – July 22, 2024 – A team of researchers at the University of Rhode Island and Nova Southeastern University in Florida have been tracking a 26-foot endangered whale shark – named “Rio Lady” – with a satellite transmitter for more than four years – a record for whale sharks and one of the longest tracking endeavors for any species of shark.

Whale sharks, which live from 80 to 130 years, are the world’s largest fish and third largest creature in the ocean – behind blue and fin whales. The size of a small school bus, they inhabit tropical oceans and swim slowly near the surface, with their mouths wide open, scooping up whatever’s in their path – small fish, fish eggs, and plankton. Annually, they need to travel about 5,000 miles to find enough food to survive. Whale shark populations worldwide have declined, primarily as a result of interactions with humans, to the point where they are now listed on the International Union for Conservation of Nature Red List as Globally Endangered.

Researchers at URI and Nova Southeastern tracked Rio Lady for about 27,000 miles over nearly 1,700 days between 2018 and 2023. Her journey took her through the Gulf of Mexico, the Caribbean and out into the Atlantic Ocean south of Bermuda. A study conducted by the researchers was published in the journal Marine and Freshwater Research, describing movement, migration and habitat use of Rio Lady.

“This was an amazing length of time to be able to track the movements of a wild animal,” said lead author Daniel Daye, who graduated from URI in May 2023 with a master’s degree in biological and environmental sciences. “Four years of data about the movements of even a single individual has allowed us to investigate whale sharks to an unprecedented degree and investigate questions that can’t be answered with shorter tracks.”

Rio Lady was tracked by satellite telemetry using a smart-position and temperature transmitter (SPOT) affixed to her dorsal fin. The tag provided location transmissions over four years of her life. Satellite telemetry has revolutionized the study of animal movement – particularly with marine species – allowing researchers to uncover long-term movement patterns and core areas for marine animals, the study says.

“As the biggest fish in the ocean, it is challenging to follow the movements of whale sharks over long periods of time,” said Brad Wetherbee, assistant professor of biological sciences at URI and an expert on shark movement and migration, who consulted on the project. “But information on the movements of these endangered sharks is important for management of their populations.”

A primary challenge in managing large marine species, such as the whale shark, said Daye, is that they are hard to follow. Whale sharks travel great distances and routinely dive deep, which makes studying the full extent of their habitat difficult.

“Since these sharks travel such great distances, it’s important to identify when and where the sharks are located, along with what they are doing in each of these areas,” said Daye. “This way management can take a more targeted approach so that effort isn’t wasted on areas when sharks are using habitats elsewhere. While Rio Lady is only one shark, the extremely long lifespan of the SPOT tag has allowed us to start examining some of these questions in more detail regarding what sharks do on a year-to-year basis, rather than a single year.”

Rio Lady was first tagged in 2007 with a pop-up satellite archival transmitter affixed to her near the Isla Mujeres, in waters off Cancun, Mexico, that are frequented by hundreds of whale sharks annually from July through August. She was tracked for 150 days before her transmitter popped off. She was re-tagged in August 2018 in the same area by Rafael de la Parra, executive director of Ch’ooj Ajauil AC, an ocean conservation organization in Mexico. De la Parra also collaborated on the study.

During the study, Rio Lady was detected by satellite over 1,687 days – Aug. 30, 2018 to April 12, 2023. For a period of about 1,085 days – Aug. 30, 2018 to Aug. 18, 2021 – 1,354 locations were recorded at relatively frequent intervals. In that time, she traveled about 27,000 miles, covering about 25 miles a day.

Researchers found that Rio Lady occupied three distinct regions in the Gulf of Mexico and timing of when these areas were used was pretty consistent, Daye said. Between July and August, she consistently returned to the waters near Isla Mujeres. In the area known as the Afuera, hundreds of whale sharks aggregate for the largest gathering worldwide – dining on an endless fish egg “buffet,” said Daye.  

After leaving the Afuera area, few detections were received during autumn and winter each year of the study. Rio Lady was believed to travel south into the Caribbean Sea, as far as Colombia for two of the years, before returning to the Gulf of Mexico early in the year. Researchers believe Rio Lady’s seasonal migration may be typical for whale sharks that aggregate off the Isla Mujeres in the summer.

“This unprecedented track of Rio Lady sheds new light on long-term consistency of movements and illustrates the type of information that this technology can generate,” said Mahmood Shivji, professor of biological sciences at Nova Southeastern University, who collaborated on the study.

Rio Lady’s continued journey can be followed on the Guy Harvey Research Institute tracking website, click on project 21.

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DOI

10.1071/MF23147 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Tracking 4 years in the life of a female whale shark shows consistent migrations in the Gulf of Mexico and Caribbean