Tenochtitlán’s lessons for the future of megacities

700 years of water adaptation in Mexico City demonstrate vulnerabilities cannot be eliminated, only negotiated

Meeting Announcement

AMERICAN GEOPHYSICAL UNION

WASHINGTON — At the time of Spanish conquest in 1521, the Aztec’s capital Tenochtitlán, now Mexico City, was already one of the largest, most populous cities in the world, managing complex problems of urban development, flooding and water supply.

The city’s ongoing struggles to balance these same issues, 500 years later,  are a case study in environmental adaption with lessons for contemporary decision makers and the future of megacities, according to Beth Tellman, a human-environmental geographer at the University of Arizona.

“Can megacities adapt to climate change, are they going to collapse, or are we going to figure it out? I think looking at Mexico City is a really interesting way to answer that question because it's a city that's been figuring it out for 700 years and that's had consequences. Some people have really gained from that adaptation and other people have lost out,” Tellman said.

One of the essential lessons from revisiting and synthesizing the many existing records of the city’s history, Tellman argues, is technological innovation alone can’t solve water problems that have social and political dimensions.

“If a new diversion protects a community from flood, but drowns another community in the diversion path, is it a success? Any time you build a levy, it's going to move water faster downstream or to the other side. We need to be thinking more about: Whose adaptation is this? Do we actually have all affected people at the table?”

Tellman will speak today about her research on how urban managers mitigate — and create — vulnerability to environmental hazards in Mexico City and other cities around the world in at 5:00 pm EDT session at the Frontiers in Hydrology meeting, convening this week in San Juan, Puerto Rico and online.

The Frontiers in Hydrology meeting is a partnership between AGU and the Consortium of Universities for the Advancement of Hydrologic Science, Inc (CUAHSI) designed to inspire new ideas and solutions for the future of water by bringing together engineers, hydrologists, social scientists, urban planners, atmospheric scientists and affiliated communities from around the world that work on all aspects of water issues.

Free media registration is available for online and in-person attendance at the meeting.

Complex trade-offs

“As cities grow and get more complex, managing risks in a separate way is a strategy that does not work and ignoring that reality makes it worse, because instead of anticipated consequences of adaptation decisions, you have these unanticipated consequences,” Tellman said.

Tenochtitlán, and later Mexico City, like many modern cities, started out managing water supply, flooding and urban development separately. But as the city grew, the three adaptation pathways intersected in complex ways, creating complicated risk trade-offs.

The city, built on an island in saline Lake Texcoco, controlled flooding through a sophisticated network of dikes, levees and canals. Aqueducts, sluices and other infrastructure provided fresh water and kept it separated from the salty lake water. But aqueducts contributed to destructive flooding, and dikes to prevent flooding in one location channeled floodwaters into others.

After conquest destroyed much of the original city infrastructure, the Spanish chose to deal with flooding by draining the lake, which created new problems. Now a megacity of 20 million, Mexico City continues to battle flooding, while simultaneously struggling with water shortages. Groundwater pumping to supply fresh water has caused the city to sink, breaking drains, which causes more flooding. Both problems hit neighborhoods unevenly, with the greatest burden falling on low-income areas, Tellman said. Technological solutions like rainwater capture do not reach people with greatest need, because of political barriers to providing city improvements to undocumented residents.

“Vulnerability cannot be eliminated,” Tellman said. “It's transferred over time or space or to different populations, and what that means is that we should not have the engineering hubris to say we're going to eliminate vulnerability. What we should instead do is democratically negotiate the consequences of adaptation. It’s not just climate adaptation, but climate justice.”

AGU (www.agu.org) supports 125,000 enthusiasts to experts worldwide in Earth and space sciences. Through broad and inclusive partnerships, we advance discovery and solution science that accelerate knowledge and create solutions that are ethical, unbiased and respectful of communities and their values. Our programs include serving as a scholarly publisher, convening virtual and in-person events and providing career support. We live our values in everything we do, such as our net zero energy renovated building in Washington, D.C. and our Ethics and Equity Center, which fosters a diverse and inclusive geoscience community to ensure responsible conduct.

Notes for journalists

Tellman will present “143-01 - The consequences of adaptation: mitigating and producing vulnerability in Mexico City” in an oral session on “ridging Resolutions: Natural Hazards & Civilization II Oral: on Monday, 19 June, at 5:00 pm Atlantic Standard Time (UTC-4 hours).

This session will not be live streamed, but reporters may gain expedited access to the session recording by emailing news@agu.org.

AGU and CUAHSI  are hosting the first biennial Frontiers in Hydrology meeting (#FIHM22) in San Juan, Puerto Rico and online, 19 – 24 June 2022.

• Media registration and eligibility
• Online and on-site press information
• Presentation abstracts and schedule

Live-streamed and recorded content

Registered media can stream plenaries, online-only oral sessions and hybrid sessions live in the meeting platform. Hybrid sessions will include presenters in person in San Juan as well as online participants. Traditional in-person-only oral sessions will be recorded and available to view in the online meeting platform within a week of the events. Live-streamed presentations will also be recorded and available for later viewing. Remote attendees have access to an online poster gallery.

 Children who had bronchitis linked to adult lung problem

Long term consequences of childhood infection explained

Peer-Reviewed Publication

UNIVERSITY OF MELBOURNE

 

IMAGE: LONG RUNNING HEALTH STUDY ESTABLISHES CONSEQUENCES OF INFECTIONS IN CHILDREN view more 

CREDIT: THE UNIVERSITY OF MELBOURNE

Bronchitis in early childhood has been found to increase the risk of lung diseases in middle age according to research from the Allergy and Lung Health Unit at the University of Melbourne.

Researchers found that Australian children who had bronchitis at least once before the age of seven were more likely to have lung problems in later life.

They also established that the lung diseases the children suffered from by the time they reached the age of 53 were usually asthma and pneumonia, rather than chronic bronchitis or chronic obstructive pulmonary disease.

Lead author of a paper published today in the journal, BMJ Open Respiratory Research, Dr Jennifer Perret, said the findings come from one of the world’s oldest surveys, the Tasmanian Longitudinal Health Study, which followed 8,583 people who were born in Tasmania in 1961 and started school in 1968.

“This is the first very long-term prospective study that has examined the relationship between childhood bronchitis severity with adult lung health outcomes. We have seen already that children with protracted bacterial bronchitis are at increased risk of serious chronic infective lung disease after two to five years, so studies like ours are documenting the potential for symptomatic children to develop lung conditions, such as asthma and lung function changes, up to mid-adult life,” she said.

Researchers established the link between childhood bronchitis and adult lung problem by surveying the original participants when they joined the study. Participants were then tracked for an average of 46 years with 42 per cent completing another questionnaire, including doctor-diagnosed lung conditions and a clinical examination, between 2012 and 2016.

By categorising participants into groups based on groups based on the number and duration of episodes of “bronchitis” and/or “loose, rattly or chesty cough”, they found that the more often a participant had been diagnosed by a doctor as having pneumonia and asthma, the more likely the participant had bronchitis as a child.

Dr Perret said the numbers in the most severe subgroup were small (just 42 participants were in this category and of these just 14 had current asthma in middle-age), but the trends across bronchitis severity categories were significant.

“Compared with the majority who never had from bronchitis, there was an incremental increase in risk for later asthma and pneumonia which strengthened the more often a person had suffered from bronchitis as a child, and especially if they had recurrent episodes which were prolonged for at least one month in duration.

“It is notable that the link with later adult active asthma was seen for participants who did not have co-existent asthma or wheezing in childhood, and a similar finding has been recently seen in a very large meta-analysis of school-aged children who had had a lower respiratory tract infection during early childhood.”

Researchers hope the study will help doctors identify children who could benefit from more careful monitoring and earlier interventions to keep them in better health into mid-adult life.

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JOURNAL

The BMJ

DOI

10.1136/bmjresp-2022-001212 

METHOD OF RESEARCH

Systematic review

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Childhood ‘bronchitis’ and respiratory outcomes in middle-age: a prospective cohort study from age 7 to 53 years

ARTICLE PUBLICATION DATE

21-Jun-2022

Walking gives the brain a ‘step-up’ in function for some

Peer-Reviewed Publication

UNIVERSITY OF ROCHESTER MEDICAL CENTER

It has long been thought that when walking is combined with a task – both suffer. Researchers at the Del Monte Institute for Neuroscience at the University of Rochester found that this is not always the case. Some young and healthy people improve performance on cognitive tasks while walking by changing the use of neural resources. However, this does not necessarily mean you should work on a big assignment while walking off that cake from the night before.

“There was no predictor of who would fall into which category before we tested them, we initially thought that everyone would respond similarly,” said Eleni Patelaki, a biomedical engineering Ph.D. student at the University of Rochester School of Medicine and Dentistry in the Frederick J. and Marion A. Schindler Cognitive Neurophysiology Laboratory and first author of the study out now in Cerebral Cortex. “It was surprising that for some of the subjects it was easier for them to do dual-tasking – do more than one task – compared to single-tasking – doing each task separately. This was interesting and unexpected because most studies in the field show that the more tasks that we have to do concurrently the lower our performance gets.”

Improving means changes in the brain

Using the Mobile Brain/Body Imaging system, or MoBI, researchers monitored the brain activity, kinematics and behavior of 26 healthy 18 to 30-year-olds as they looked at a series of images, either while sitting on a chair or walking on a treadmill. Participants were instructed to click a button each time the image changed. If the same image appeared back-to-back participants were asked to not click.

Performance achieved by each participant in this task while sitting was considered their personal behavioral “baseline”. When walking was added to performing the same task, investigators found that different behaviors appeared, with some people performing worse than their sitting baseline - as expected based on previous studies - but also with some others improving compared to their sitting baseline. The electroencephalogram, or EEG, data showed that the 14 participants who improved at the task while walking had a change in frontal brain function which was absent in the 12 participants who did not improve. This brain activity change exhibited by those who improved at the task suggests increased flexibility or efficiency in the brain.

“To the naked eye, there were no differences in our participants. It wasn’t until we started analyzing their behavior and brain activity that we found the surprising difference in the group's neural signature and what makes them handle complex dual-tasking processes differently,” Patelaki said. “These findings have the potential to be expanded and translated to populations where we know that flexibility of neural resources gets compromised.”

Edward Freedman, Ph.D., associate professor of Neuroscience at the Del Monte Institute led this research that continues to expand how the MoBI is helping neuroscientists discover the mechanisms at work when the brain takes on multiple tasks. His previous work has highlighted the flexibility of a healthy brain, showing the more difficult the task the greater the neurophysiological difference between walking and sitting. “These new findings highlight that the MoBI can show us how the brain responds to walking and how the brain responds to the task,” Freedman said. “This gives us a place to start looking in the brains of older adults, especially healthy ones.”

Impact on aging

Expanding this research to older adults could guide scientists to identify a possible marker for ‘super agers’ or people who have a minimal decline in cognitive functions. This marker would be useful in helping better understand what could be going awry in neurodegenerative diseases.

Additional authors include John Foxe, Ph.D., and Kevin Mazurek, Ph.D., of the University of Rochester Medical Center. This research was supported by the Del Monte Institute for Neuroscience Pilot Program, the University of Rochester CTSA award number KL2 TR001999 from the National Center for Advancing Translational Sciences of the National Institutes of Health, and the National Institutes of Health. Recordings were conducted at the University of Rochester Intellectual and Developmental Disabilities Research Center (UR-IDDRC).

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JOURNAL

Cerebral Cortex

DOI

10.1093/cercor/bhac227 

Economists Show International Trade Can Worsen Income Inequality

By PETER DIZIKES, MASSACHUSETTS INSTITUTE OF TECHNOLOGY JUNE 19, 2022

MIT economists studying individual income data in Ecuador found that international trade generates income gains that are about 7 percent greater for those at the 90th income percentile, compared to those of median income, and up to 11 percent greater for the top percentile of income. Credit: MIT News

Using Ecuador as a case study, economists show international trade widens the income gap in individual countries.

International trade intensifies domestic income inequality, at least in some circumstances, according to a new empirical study that two MIT economists helped co-author.

The research, focusing on Ecuador as a case study, digs into individual-level income data while examining in close detail the connections between Ecuador’s economy and international trade. The study finds that trade generates income gains that are about 7 percent greater for those at the 90th income percentile, compared to those of median income, and up to 11 percent greater for the top percentile of income in Ecuador.

“Earnings inequality is higher in Ecuador than it would be in the absence of trade.”

“Trade in Ecuador tends to be something that is good for the richest, relative to the middle class,” says Dave Donaldson, a professor in the MIT Department of Economics and co-author of a published paper detailing the findings. “It’s pretty neutral in terms of the middle class relative to the poorest. The [largest benefits] are found both among those who have founded businesses, as well as those who are well off and work as employees. So, it’s both a labor and capital effect at the top.”

The study also identifies the dynamics that generate this outcome. Ecuadorian exports, mostly commodities and raw goods, tend to help the middle class or those less well-off, while the country’s import activities generally help the already well-off — and overall, importing has a bigger effect.

“There is a horse race between the export channel and the import channel,” says Arnaud Costinot, also a professor in the MIT Department of Economics and co-author of the paper. “Ultimately, what is quantitatively more important in the data, in the case of Ecuador, is the import channel.”

The paper, “Imports, Exports, and Earnings Inequality: Measures of Exposure and Estimates of Incidence,” appears online in the Quarterly Journal of Economics. The authors are Rodrigo Adao, an associate professor at the University of Chicago Booth School of Business; Paul Carillo, a professor of economics and international affairs at George Washington University; Costinot, who is also associate head of MIT’s Department of Economics; Donaldson; and Dina Pomeranz, an assistant professor of economics at the University of Zurich.

Commodities out, machinery in

The effect of international trade on a nation’s income distribution is hard to pinpoint. Economists cannot, after all, devise a country-size experiment and study the same nation, both with and without trade involvement, to see if differences emerge.

As an alternate strategy, the scholars developed an unusually detailed reconstruction of trade-related economic activity in Ecuador. For the period from 2009 to 2015, they examined revenue from 1.5 million firms with a tax ID, and income for 2.9 million founders and employees of those firms. The scholars collected revenue data, payments to labor, and divided up individual income data according to three levels of education (ending before high school, high school graduates, and college graduates) across all 24 provinces in Ecuador.

Digging further, the research team compiled customs records, VAT (Value-Added Tax) data on purchases, and domestic firm-to-firm trade data, to develop a broad and detailed picture of the value of imports and exports, as well as business transactions that occurred domestically but were related to international trade.

Overall, oil accounted for 54 percent of Ecuador’s exports in the period from 2009 to 2011, followed by fruits (11 percent), seafood products (10 percent), and flowers (4 percent). But Ecuador’s imports are mostly manufactured products, including machinery (21 percent of imports), chemicals (14 percent), and vehicles (13 percent).

This composition of imports and exports — commodities out, manufactured goods in — turns out to be crucial to the relationship between trade and greater income inequality in Ecuador. Firms that employ well-educated, better-paid individuals also tend to be the ones benefitting from trade more because it allows their firms to buy manufactured goods more cheaply and flourish, in turn bolstering demand for more extensively educated workers.

“It’s all about whether trade increases demand for your services,” Costinot says.

“The thing that is happening in Ecuador is that the richest individuals tend to be employed by firms that directly import a lot, or tend to be employed by firms that are buying a lot of goods from other Ecuadorian firms that import a lot. Getting access to these imported inputs lowers their costs and increases demand for the services of their workers.”

For this reason, ultimately, “earnings inequality is higher in Ecuador than it would be in the absence of trade,” as the paper states.

Reconsidering trade ideas

As Costinot and Donaldson observe, this core finding runs counter what some portions of established trade theory would expect. For instance, some earlier theories would anticipate that opening up Ecuador to trade would bolster the country’s relatively larger portion of lower-skilled workers.

“It’s not what a standard theory would have predicted,” Costinot says. “A standard theory would be one where [because] Ecuador has [a] relatively scarcity, compared to a country like the U.S., of skilled workers, not unskilled workers, as Ecuador turns to trade, the low-skilled workers should be the ones benefitting relatively more. We found the opposite.”

Additionally, Donaldson notes, some trade theories incorporate the idea of “perfect substitution,” that like goods will be traded among countries — with level wages resulting. But not in Ecuador, at least.

“This is the idea that you could have a country making a good and other countries making an identical good, and ‘perfect substitution’ across countries would create strong pressure to equalize wages in the two countries,” Donaldson says. “Because they’re both making the same good in the same way, they can’t pay their workers differently.” However, he adds, while “earlier thinkers [economists] didn’t think it was literally true, it’s still a question of how strong that force is. Our findings suggest that force is quite weak.”

Costinot and Donaldson acknowledge that their study must take into account a variety of complexities. For instance, they note, about half of Ecuador’s economy is informal, and cannot be measured using official records. Additionally, global “shocks” can affect trade patterns in a given country at a given time — something they test for and incorporate into the current study.

And while trade patterns can also change more gradually, the data from the 2009-2015 time period are stable enough to suggest that the researchers identified a clear and ongoing trend in Ecuador.

“People don’t change jobs very often, and the income distribution does not change very much,” Donaldson says. “We did make sure to check that — within the sample, the stability is very high.”

A global pattern?

The study also naturally raises the question of whether similar outcomes might be found in other countries. In the paper, the authors list many other countries to which their methods could be applied.

“Ecuador is definitely very different from the United States, but it’s not very different from many middle-income countries that are mostly exporting commodities in exchange for manufactured goods,” Costinot says. Donaldson, for his part, is already working on a similar project in Chile.

“That pattern of participation [in global trade] is important, and exporting could be very different across countries,” Donaldson says. “But it would be very easy to know, if you just found the data.”

Reference: “Imports, Exports, and Earnings Inequality: Measures of Exposure and Estimates of Incidence” by Rodrigo Adão, Paul Carrillo, Arnaud Costinot, Dave Donaldson and Dina Pomeranz, 2 March 2022, The Quarterly Journal of Economics.
DOI: 10.1093/qje/qjac012

Support for the research was provided, in part, by the U.S. National Science Foundation, the Center for Economic Policy Research, the U.K. Department for International Development, and the European Research Council.

New Understanding of Earth’s Architecture: Updated Maps of Tectonic Plates

By UNIVERSITY OF ADELAIDE JUNE 19, 2022

New tectonic plate model with boundary zones in darker shading. Credit: Dr. Derrick Hasterok, University of Adelaide 

New models that show how the continents were assembled are providing fresh insights into the history of the Earth and will help provide a better understanding of natural hazards like earthquakes and volcanoes.

“We looked at the current knowledge of the configuration of plate boundary zones and the past construction of the continental crust,” said Dr. Derrick Hasterok, Lecturer, Department of Earth Sciences, University of Adelaide who led the team that produced the new models.

“The continents were assembled a few pieces at a time, a bit like a jigsaw, but each time the puzzle was finished it was cut up and reorganized to produce a new picture. Our study helps illuminate the various components so geologists can piece together the previous images.

“We found that plate boundary zones account for nearly 16 percent of the Earth’s crust and an even higher proportion, 27 percent, of continents.”

“Our new model for tectonic plates better explains the spatial distribution of 90 per cent of earthquakes and 80 per cent of volcanoes from the past two million years whereas existing models only capture 65 percent of earthquakes.”

— Dr. Derrick Hasterok, Lecturer, Department of Earth Sciences, University of Adelaide

New models showing the Earth’s architecture. Credit: Dr. Derrick Hasterok, University of Adelaide

The team produced three new geological models: a plate model, a province model, and an orogeny model.

“There are 26 orogenies – the process of mountain formation – that have left an imprint on the present-day architecture of the crust. Many of these, but not all, are related to the formation of supercontinents,” said Dr. Hasterok.

“Our work allows us to update maps of tectonic plates and the formation of continents that are found in classroom textbooks. These plate models which have been assembled from topographic models and global seismicity, have not been updated since 2003.”

The new plate model includes several new microplates including the Macquarie microplate which sits south of Tasmania and the Capricorn microplate which separates the Indian and Australian plates

“To further enrich the model, we added more accurate information about the boundaries of deformation zones: previous models showed these as discrete areas rather than wide zones,” said Dr. Hasterok.

“The biggest changes to the plate model have been in western North America, which often has the boundary with the Pacific Plate drawn as the San Andreas and Queen Charlotte Faults. But the newly delineated boundary is much wider, approximately 1500 km, than the previously drawn narrow zone.

“The other large change is in central Asia. The new model now includes all the deformation zones north of India as the plate bulldozes its way into Eurasia.”

A tale told by the continents. Credit: Dr. Derrick Hasterok, University of Adelaide

Published in the journal Earth-Science Reviews, the team’s work provides a more accurate representation of the Earth’s architecture and has other important applications.

“Our new model for tectonic plates better explains the spatial distribution of 90 percent of earthquakes and 80 percent of volcanoes from the past two million years whereas existing models only capture 65 percent of earthquakes,” said Dr. Hasterok.

“The plate model can be used to improve models of risks from geohazards; the orogeny model helps understand the geodynamic systems and better model Earth’s evolution and the province model can be used to improve prospecting for minerals.”

Reference: “New Maps of Global Geological Provinces and Tectonic Plates” by Derrick Hasterok, Jacqueline A. Halpin, Alan S. Collins, Martin Hand, Corné Kreemer, Matthew G. Gard and Stijn Glorie, 31 May 2022, Earth-Science Reviews.
DOI: 10.1016/j.earscirev.2022.104069

The work included researchers at the Universities of Adelaide, Tasmania, Nevada-Reno, and Geoscience Australia

419-Million-Year-Old Chinese Fossil Shows Human Middle Ear Evolved From Fish Gills

JUNE 20, 2022

The 3D braincase of Shuyu. Credit: IVP

The human middle ear—which houses three tiny, vibrating bones—is key to transporting sound vibrations into the inner ear, where they become nerve impulses that allow us to hear.

Embryonic and fossil evidence proves that the human middle ear evolved from the spiracle of fishes. However, the origin of the vertebrate spiracle has long been an unsolved mystery in vertebrate evolution.

“These fossils provided the first anatomical and fossil evidence for a vertebrate spiracle originating from fish gills.” — Prof. GAI Zhikun

Some 20^th century researchers, believing that early vertebrates must possess a complete spiracular gill, searched for one between the mandibular and hyoid arches of early vertebrates. Despite extensive research spanning more than a century, though, none were found in any vertebrate fossils.

Now, however, scientists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences and their collaborators have found clues to this mystery from armored galeaspid fossils in China.

Their findings were published in the journal Frontiers in Ecology and Evolution on May 19, 2022.

According to Prof. GAI Zhikun from IVPP, first author of the study, researchers from the institute successively found over the last 20 years a 438-million-year-old Shuyu 3D braincase fossil and the first 419-million-year-old galeaspid fossil completely preserved with gill filaments in the first branchial chamber. The fossils were found in Changxing, Zhejiang Province and Qujing, Yunnan Province, respectively.

The 3D virtual reconstruction of Shuyu. Credit: IVPP

“These fossils provided the first anatomical and fossil evidence for a vertebrate spiracle originating from fish gills,” said GAI.

A total of seven virtual endocasts of the Shuyu braincase were subsequently reconstructed. Almost all details of the cranial anatomy of Shuyu were revealed in its fingernail-sized skull, including five brain divisions, sensory organs, and cranial nerve and blood vessel passages in the skull.

“Many important structures of human beings can be traced back to our fish ancestors, such as our teeth, jaws, middle ears, etc. The main task of paleontologists is to find the important missing links in the evolutionary chain from fish to humans. Shuyu has been regarded as a key missing link as important as Archaeopteryx, Ichthyostega and Tiktaalik,” said ZHU Min, academician of the Chinese Academy of Sciences.

The first 419-million-year-old galeaspid fossil completely preserved with 

gill filaments in the first branchial chamber. Credit: IVPP

The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In sharks and all rays, the spiracle is responsible for the intake of water into the buccal space before being expelled from the gills. The spiracle is often located towards the top of the animal allowing breathing even while the animal is mostly buried under sediment.

In the Polypterus, the most primitive, living bony fish, the spiracles are used to breathe air. However, fish spiracles were eventually replaced in most non-fish species as they evolved to breathe through their noses and mouths. In early tetrapods, the spiracle seems to have developed first into the Otic notch. Like the spiracle, it was used in respiration and was incapable of sensing sound. Later the spiracle evolved into the ear of modern tetrapods, eventually becoming the hearing canal used for transmitting sound to the brain via tiny inner ear bones. This function has remained throughout the evolution to humans.

“Our finding bridges the entire history of the spiracular slit, bringing together recent discoveries from the gill pouches of fossil jawless vertebrates, via the spiracles of the earliest jawed vertebrates, to the middle ears of the first tetrapods, which tells this extraordinary evolutionary story,” said Prof. Per E. Ahlberg from Uppsala University and academician of the Royal Swedish Academy of Sciences.

Reference: “The Evolution of the Spiracular Region From Jawless Fishes to Tetrapods” by Zhikun Gai, Min Zhu, Per E. Ahlberg and Philip C. J. Donoghue, 19 May 2022, Frontiers in Ecology and Evolution.
DOI: 10.3389/fevo.2022.887172

Sharks may be closer to the city than you think, new study finds

Unlike big land predators, the ocean’s top predators don’t avoid urban areas

Peer-Reviewed Publication

UNIVERSITY OF MIAMI ROSENSTIEL SCHOOL OF MARINE & ATMOSPHERIC SCIENCE

 

VIDEO: A GREAT HAMMERHEAD EXPLORING THE SHALLOWS OFF MIAMI BEACH CRUISES UNDER A SWIMMER. view more 

CREDIT: VIDEO CREDIT: JMAC / JASON MCINTOSH

MIAMI— The world’s coastlines are rapidly urbanizing, but how this increased human presence may impact species living in the ocean is not fully understood. In a new study led by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, researchers tracked the movements of three shark species, bull, nurse and great hammerhead, in relation to the city of Miami. Given the chemical, light, and noise pollution emanating from the coastal metropolis, researchers expected sharks to avoid areas close to the city, but that’s not what they found.

Some animals, like pigeons and racoons, thrive in cities. These species, known as “urban exploiters,” often become dependent on human garbage for food. Other animals, known as “urban adapters,” may show some use of urbanized areas, but still largely rely on natural areas. On the other hand, some species such as land predators such as wolves are very sensitive to human disturbance. These “urban avoiders” avoid big cities.

“Few studies have investigated the movements of ocean predators in relation to urbanization, but since other studies have shown that land predators are urban avoiders, we expected sharks to be too,” said Neil Hammerschlag, director of the UM Shark Research and Conservation Program and lead author of the study. “We were surprised to find that the sharks we tracked spent so much time near the lights and sounds of the busy city, often close to shore, no matter the time of day.” The researchers concluded that the behaviors of the tracked sharks resembled that of “urban adapters”. The study speculates sharks could be attracted to shore from land-based activities, such as the discarding of fish carcasses.

The relatively high use of urban-impacted areas by the tracked sharks may have consequences for both sharks and humans. “By spending so much time close to shore, sharks are at risk of exposure to toxic pollutants as well as fishing, which could impact their health and survival,” said Hammerschlag. While shark bites on humans are rare, the study also pinpoints areas close to shore that could be avoided by human water users to reduce probability of a negative shark encounter, promoting human-shark coexistence.

The study, titled “Urban Sharks: Residency patterns of marine top predators in relation to a coastal metropolis” was published June 16, 2022 in the journal Marine Ecology Progress Series.

The study’s authors include: Neil Hammerschlag, Mitchell Rider from the UM Rosenstiel School, and Robbie Roemer, from Ocearch; Austin J. Gallagher from Beneath the Waves; and Lee Gutowsky from Trent University.

This research was funded through support from the Ocean Tracking Network, the Disney Conservation Fund, the Save Our Seas Foundation, the National Oceanic and Atmospheric Administration (NOAA) Southeast Fisheries Science Center, the Batchelor Foundation, the Herbert W. Hoover Foundation, Ruta Maya Coffee, the International Seakeepers Society, and through a grant ‘Implementing a Marine Biodiversity Observation Network (MBON) in South Florida to Advance Ecosystem-Based Management’ funded under the National Oceanographic Partnership Program (NOPP, RFP ONR BAA #N00014-18-S-B007, in partnership with NOAA, BOEM, and NASA) and the US Integrated Ocean Observing System (IOOS) Program Office.

  

CAPTION

Researchers release an acoustically tagged nurse shark into waters off Miami, Florida, to investigate shark residency patterns in relation to coastal urbanization.

CREDIT

Robbie Roemer.

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JOURNAL

Marine Ecology Progress Series

DOI

10.3354/meps14086 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Urban Sharks: Residency patterns of marine top predators in relation to a coastal metropolis

ARTICLE PUBLICATION DATE

16-Jun-2022