Saturday, February 15, 2020

When frogs die off, snake diversity plummets

Conceptual diagram of the cascading effects of amphibian losses (shadowed in red) on other taxonomic groups. This study documents the collapse of snake diversity (shadowed in orange) after amphibian mass mortality from an invasive fungal pathogen. Other studies have documented changes in the structure and functional diversity of macroinvertebrates, primary producers, and inorganic and organic material (shadowed in yellow). Additional taxa in the ecosystem (shadowed in white) could also be impacted by amphibian declines but this may never be known because of data limitations. Credit: Mollie Newman

Since 1998, scientists have documented the global loss of amphibians. More than 500 amphibian species have declined in numbers, including 90 that have gone extinct, due to the fungal pathogen Batrachochytrium, commonly known as chytrid.

A new study by researchers from the University of Maryland and Michigan State University shows, for the first time, the ripple effects of amphibian losses on snakes. The results, published in the February 14, 2020, issue of the journal Science, reveal that after chytrid swept through a remote forest in Panama, decimating frog populations, the number of snake species scientists detected declined dramatically, causing the snake community to become more homogenized.

"This study highlights the invisibility of other changes that are occurring as a result of losing amphibians," said Karen Lips, a professor of biology at UMD and a co-author of the study.

Many snakes rely on frogs and frog eggs as part of their diet, so the researchers expected a decline in frogs to impact snake populations. But the slithery reptiles are notoriously cryptic and difficult to study in the wild. How snakes fare following a chytrid epidemic was mostly a matter of conjecture before this study.

Lips and her colleagues compared seven years of survey data collected in a national park near El Copé, Panama, before the 2004 chytrid outbreak caused mass amphibian die-off, with six years of survey data collected after the die-off.

When frogs die off, snake diversity plummets — A beautiful oxyrophus on the forest floor in Panama Credit: Credit Kelly Zamudio

"Comparing the after with the before, there was a huge shift in the snake community," Lips said. "The community became more homogeneous. The number of species declined, with many species going down in their occurrence rates, while a few species increased. Body condition of many snakes was also worse right after the frog decline. Many were thinner, and it looked like they were starving."

The researchers cannot say exactly how many snake species declined because snake sightings are rare in general. Some species were only seen once in the pre-chytrid surveys. The researchers could not confirm that a species had disappeared just because it was absent in the post-chytrid surveys. However, over half of the most common snakes (those observed more than five times throughout the total study) had declined in occurrence rates after the frog die-off. Further statistical analysis of the data confirmed a considerable drop in species diversity.

Frogs and their eggs are an important source of nutrition for many snakes.

Researchers are confident the changes they observed in the snake community were due to the loss of amphibians and not some other environmental factor. The study area is in a national park with limited impacts from habitat loss, development, pollution or other phenomena that might affect snake populations directly. The remoteness of the El Copé research site and the fact that Lips had been conducting annual surveys there in the years prior to the chytrid epidemic combined to provide a rare window into the rapid changes in an ecosystem following the catastrophic loss of amphibians.

A cat-eyed snake eats a toad in Panama. Many snakes depend on amphibians and their eggs for nutrition. Credit: Karen Warkentin When frogs die off, snake diversity plummets

"This work emphasizes the importance of long-term studies to our understanding of the invisible, cascading effects of species extinctions," Lips said. "Everything we watched changed after the frogs declined. We have to know what we are losing, or we run the risk of undermining effective conservation."

The research paper, "Tropical snake diversity collapses after widespread amphibian loss," Elise F. Zipkin, Graziella V. DiRenzo, Julie M. Ray, Sam Rossman, Karen R. Lips, was published in the February 14, 2020, issue of the journal Science.

Tropical frogs found to coexist with deadly fungus

More information: E.F. Zipkin el al., "Tropical snake diversity collapses after widespread amphibian loss," Science (2020). science.sciencemag.org/lookup/ … 1126/science.aay5733

DOWN UNDER FIRE AND FLOODS BUT NO LOCUSTS

FEBRUARY 13, 2020

Heavy rains are great news for Sydney's dams, but they come with a big caveat

by Ian Wright and Jason Reynolds, The Conversation

Throughout summer, Sydney's water storage level fell alarmingly. Level 2 water restrictions were imposed and the New South Wales government prepared to double the capacity of its desalination plant.

But then it began to rain, and rain. Sydney water storages jumped from 41% in early February to 75% now – the highest of any capital city in Australia.

This is great news for the city, but it comes with a big caveat. Floodwaters will undoubtedly wash bushfire debris into reservoirs—possibly overwhelming water treatment systems. We must prepare now for that worst-case pollution scenario.

Reservoirs filled with rain

The water level of Sydney's massive Lake Burragorang—the reservoir behind Warragamba Dam—rose by more than 11 meters this week. Warragamba supplies more than 80% of Sydney's water.

Other Sydney water storages, including Nepean and Tallowa dams, are now at 100%.WaterNSW report that 865,078 megaliters of extra water has been captured this week across all Greater Sydney's dams.

This dwarfs the volume of water produced by Sydney's desalination plant, which produces 250 megaliters a day when operating at full capacity. Even at this rate, it would take more than 3,400 days (or nine years) to match the volume of water to added to Sydney's supply this week.

But then comes the pollution

Thankfully, the rain appears to have extinguished bushfires burning in the Warragamba catchment for months.

But the water will also pick up bushfire debris and wash it into dams.

Over the summer, bushfires burnt about 30% of Warragamba Dam's massive 905,000 hectare water catchment, reducing protective ground cover vegetation. This increases the risk of soil erosion. Rain will wash ash and sediment loads into waterways—adding more nitrogen, phosphorous and organic carbon into water storages.

Waterways and ecosystems require nutrients like phosphorous and nitrogen, but excess nutrients aren't a good thing. They bring contamination risks, such as the rapid growth of toxic blue-green algae.

Drinking water catchments will always have some degree of contamination and water treatment consistently provides high quality drinking water. But poor water quality after catchment floods is not without precedent.

We've seen this before

In August 1998, extreme wet weather and flooding rivers filled the drought-affected Warragamba Dam in just a few days.

This triggered the Cryptosporidium crisis, when the protozoan parasite and the pathogen Giardia were detected in Sydney's water supplies. It triggered health warnings, and Sydneysiders were instructed to boil water before drinking it. This event did not involve a bushfire.

The Canberra bushfires in January 2003 triggered multiple water quality problems. Most of the region's Cotter River catchments, which hold three dams, were burned. Intense thunderstorms in the months after the bushfire washed enormous loads of ash, soil and debris into catchment rivers and water reservoirs.

This led to turbidity (murkiness), as well as iron, manganese, nitrogen, phosphorus and carbon in reservoir waters. The inflow of organic material also depleted dissolved oxygen which triggered the release of metals from reservoir sediment. At times, water quality was so poor it couldn't be treated and supplied to consumers.

The ACT Government was forced to impose water restrictions, and built a A$38 million water treatment plant.

Have we come far enough?

Technology in water treatment plants has developed over the past 20 years, and water supply systems operates according to Australian drinking water guidelines.

Unlike the 1998 Sydney water crisis, WaterNSW, Sydney Water and NSW Health now have advanced tests and procedures to detect and manage water quality problems.

In December last year, WaterNSW said it was aware of the risk bushfires posed to water supplies, and it had a number of measures at its disposal, including using booms and curtains to isolate affected flows.

However at the time, bushfire ash had already reportedly entered the Warragamba system.

Look to recycled water

Sydney's water storages may have filled, but residents should not stop saving water. We recommend Level 2 water restrictions, which ban the use of garden hoses, be relaxed to Level 1 restrictions which ban most sprinklers and watering systems, and the hosing of hard surfaces.

While this measure is in place, longer term solutions can be explored. Expanding desalination is a popular but expensive option, however greater use of recycled wastewater is also needed.

Highly treated recycled water including urban stormwater and even treated sewage should be purified and incorporated into the water supply. Singapore is a world leader and has proven the measure can gain community acceptance.

It's too early to tell what impact the combination of bushfires and floods will have on water storages. But as extreme weather events increase in frequency and severity, all options should be on the table to shore up drinking water supplies.

Dams overflow as Australia braces for more floods

FEBRUARY 13, 2020

Recent downpours have brought chaos and destruction to towns and cities along the eastern seaboard

Dams near Sydney overflowed Thursday after days of torrential rain, as Australia braced for more storms expected to bring dangerous flash flooding to the country's east.

Recent downpours have brought relief to areas ravaged by bushfires and drought—as well as chaos and destruction to towns and cities along the eastern seaboard.

On Thursday, Nepean Dam south of Sydney was at full capacity and spilling over, with video footage showing excess water cascading over the dam wall and downstream.

Two other dams in New South Wales, Tallowa and Brogo, were also overflowing and more dams could reach capacity in the coming days, a WaterNSW spokesman told AFP.

Sydney's dams have seen water levels spike dramatically—the Nepean was just a third full less than a week ago—though many inland areas are facing severe water shortages missed out on the flows.

A devastating months-long bushfire crisis that killed 33 people has effectively been ended by the downpours, with just one blaze yet to be brought under control in New South Wales.

Hundreds of people have been rescued from floodwaters in recent days.

Police said a man's body was discovered in a flooded river on Queensland's Sunshine Coast on Thursday, though the cause of his death was not immediately clear.

Wild weather is set to ramp up again from Friday, with the Bureau of Meteorology forecasting ex-Tropical Cyclone Uesi would bring "damaging to destructive winds" and heavy rainfall to remote tourist destination Lord Howe Island.

Senior meteorologist Grace Legge said storms were also expected for Queensland and New South Wales—with areas still recovering from bushfires likely to be hit again.

"Any showers and thunderstorms that do develop are falling on already saturated catchments, so there is a risk with severe thunderstorms of flash flooding," she said.

Emergency services have warned residents in affected areas to be cautious in the dangerous conditions.

FEBRUARY 11, 2020

Floods fail to end Australia's years-long drought

Heavy rain has given hope to Australia's drought-stricken regions, but scientists warned Tuesday sustained falls were needed to end a years-long dry spell.

Stormy weather has brought days of chaos and destruction in the country's east, with one man missing after his car was swept off a road in Sydney's north and hundreds more rescued from floodwaters.

In the small town of Stanthorpe, Queensland, Tracy Dobie said the rain had been "a boost for everyone".

"But the drought has not ended," the regional mayor told AFP.

"Our land is so dehydrated—we've gone three years without rain in some places and five years in others—it's going to take a long time to get moisture back in the soil."

Hydrologists believe this week's deluge—which has caused flooding and doused many fires—is a taste of things to come, with cities getting inundated while rural areas struggle to offset worsening droughts.

Professor Ashish Sharma from the University of New South Wales said heavy rain can give people in cities a "twisted view" of the impact, as water builds up on hard surfaces.

Even as people in cities see flooding and property damage, in rural regions sustained rainfall is needed to soak through the dry soil before dams fill.

During the latest downpours—the heaviest in 30 years in some areas—dam levels near Sydney have risen dramatically.

But most of New South Wales' drought-hit towns facing down a water "Day Zero" had seen "negligible" increases, as much of the rain was flowing into rivers not dams, said a spokesman for WaterNSW, which manages the state's water resources.

"Unfortunately (that is) largely because the volume hasn't been sufficient and the catchments are extremely dry after a very hot start to the summer and a prolonged drought," he said.

Despite climate change driving increases in extreme rainfall, Sharma and his team predict it will not be enough to keep up with rising temperatures.

Moderate and frequent floods, which form "the backbone of all our water supply", will likely decrease, Sharma said.

"I just hope that people have the wisdom and the foresight to realise that this should not be seen as a sign of not needing to act," he added.

Dobie said the rain was more than welcome but "one rain event doesn't close the door on the drought".

"We need a year of average rainfall."

FEBRUARY 10, 2020

Downpours to end Australia bushfires within days

UH NO

The catastrophic bushfires have left dozens dead and devastated vast swathes of the country since September

Australia's months-long bushfires crisis will likely be over within days, officials said Monday as heavy rainfall extinguished several massive blazes and was forecast to douse dozens more as downpours swept south.

Days of torrential rains have caused flash flooding in New South Wales and Queensland, dampening once-raging fires that volunteers had battled in vain for months.

Sydney experienced its wettest period in 20 years amid several days of heavy rainfall that led to chaotic scenes across the city.

The Bureau of Meteorology said 391.6mm (15.42 inches) of rain fell in Sydney over the past four days—the highest total in such a period since 414.2mm were recorded in February 1990.

Several major bushfires have been extinguished by the deluge, including a "mega-blaze" that burned through 500,000 hectares (1.2 million acres) north of Sydney and a similar-sized fire to the city's south, bringing relief to residents and firefighters.

New South Wales Rural Fire Service spokesman James Morris said about 30 fires were still burning Monday, but it was expected they would soon be extinguished as the rain moves south in the coming days.

"By the end of the week it's likely they will be out," he told AFP.

Drought-stricken areas across the country's east also received welcome downpours but more sustained and widespread rainfall will be needed to offset a years-long dry spell.

The stormy weather has brought days of chaos and destruction, with one man missing after his car was swept off a road in Sydney's north and hundreds more rescued from floodwaters across the state.

Police said a search was under way for the missing man Monday but no sign of him or his vehicle had been found.

Several rivers, including the Parramatta River in Sydney's west, overflowed while residents living near Narrabeen Lagoon in the city's north were ordered to evacuate late Sunday amid fears their homes could be inundated.

Emergency services scrambled to respond to calls for assistance as strong winds uprooted trees, ocean foam coated seaside homes and boulders fell on parked cars.

Almost 90,000 homes remained without power Monday, with utility providers warning it could take days for electricity to be restored in some areas.

The Insurance Council of Australia said insurers had received an estimated Aus$45 million ($30 million) in claims by early Monday, with that figure expected to rise as the full extent of the damage becomes clear

Understanding different brown bear personalities may help reduce clashes with people

by Anthony King, From Horizon Magazine,
Horizon: The EU Research & Innovation Magazine

Understanding different brown bear personalities may help reduce clashes with people

Brown bears show individuality in the distance they travel each day, their preference for daytime or night-time movement and other behaviours, according to research. Credit: Rufus46, licensed under CC BY-SA 3.The brown bear is one of Europe's five large carnivores and can sometimes cross paths with people, with potentially fatal consequences. But bears have different personalities and behaviours, say researchers, and understanding this is the key to reducing conflict and protecting both them and humans.

Brown bears once thrived in woodlands throughout Europe, but human persecution decimated their numbers. Today, populations are highest in mountainous rural regions close to the Balkans and Carpathian Mountains, which are home to around 12,000 of Europe's 17,000 brown bears.

With greater legal protections, bears are recovering and recolonising landscapes, such as the Alps and Pyrenees. The challenge now is in managing co-existence of people and carnivores, as brown bears prey on livestock, raid beehives and sometimes pose a threat to people.

In Romania, home to an estimated 6,000 bears, they may enter villages, towns, even cities. They can maim or kill people, with brown bears being responsible for multiple deaths in 2019.

People are also a problem for the bears. "We have this return of large carnivores often returning to landscapes that are human dominated and that is a challenge for many of the carnivores themselves," said Professor Thomas Mueller, an expert in animal movements at the Senckenberg Biodiversity and Climate Research Centre in Frankfurt, Germany.

Adolescent bears typically can suffer high death rates, for example due to road collisions.

Understanding carnivore behaviour is one way to help manage conflict between people and animals, said Prof. Mueller.

Movements

According to Dr. Anne Hertel, who studies bear behaviour as part of Prof Mueller's group, this needs to be done at an individual level. As part of her Ph.D. studies at the Norwegian University of Life Sciences, she tracked bear movements in Swedish forests, examining how they foraged, avoided humans and selected areas to live.

Bears hibernate in dens from November to April, when females give birth to cubs. Females stay with their mothers for around two years and set up home nearby, whereas males disperse much further. Dr. Hertel never once chanced upon a wild bear in Sweden.

"They avoid humans at all cost, which makes studying their personality hard," she explained. She relied on movement data from radio-collared bears, generally captured as cubs with their mother in their second year. Before release, a sample of hair was taken.

By tracking 46 adult brown bears, she identified six ways in which bears' behaviour can vary: the distance they travel per day, the distance between where they began and where they ended up each day, their preference for night-time or day-time movement, and whether they liked or avoided open areas including roads, bogs and forest clearings.

"We find that bear behaviour is consistent over time, with some more active in daytime, and some selecting habitat closer to roads, or more open habitat such as bogs and clear-cut forest," Dr. Hertel said. "Bears are quite different from each other. Nocturnal bears tend to be quite sedentary, while others more active during daytime move a lot."

Carnivory

Swedish bears eat mostly forest berries, but some have a higher meat intake, preying on young moose. Dr. Hertel is determining which bears eat more meat by examining a chemical signature in the hair collected. "Our next step is to see whether carnivory is a trait which can be learnt from their mother," she said.

Europe, according to the IUCN's Large Carnivore Initiative for Europe, 44% of which live in the Carpathian mountains, which span Romania, Poland, Slovakia and Serbia. Credit: Horizon

She is also trying to work out how individuality in behaviour can change over time through learning, or remain stable, and whether it can be predicted, as part of a project called PERSONALMOVE. Her findings could feed into predictions of bear movements, especially of young males which disperse to establish new territories, and help understand which ones are most likely to move through areas where people live.

Whether findings from Sweden can be translated to other parts of Europe, such as Romania, is unclear as conditions are different and there is very little data to test the hypothesis, says Dr. Hertel.

"Romania is one country in Europe which has the most bears by far, and they have more conflict in terms of them entering human settlements and causing problems," she said. She believes that this conflict stems from a combination of bear behavioural traits, opportunities for them to feed on foods like human trash and management techniques.

Hunting

Romania traditionally allowed bear hunting, but when it entered the EU in 2007, bears became a protected species. Hunting was banned altogether in 2016, but it is difficult to know the effect this has had on bear populations as there is no data available.

"Previously, populations were managed in order to maximise hunting bags," said Dr. Valeria Salvatori at the Istituto di Ecologia Applicata in Italy. "The population of bears in Romania has been maintained at artificially high levels through artificial feeding for decades."

Forestry activity has risen since the country joined the EU, and some suggest that disturbance is driving bears out to search villages for food. But Dr. Salvatori had first seen bears eating from city garbage dumps almost two decades ago, when she did Ph.D. research in the Carpathians.

While pro-hunting groups highlight conflicts between bears and people, Dr. Salvatori says that in rural areas, attitudes towards bears are not negative.

In places such as Hargita, a hotspot for bears in Transylvania, people believe that the current situation and the damage being caused by bears is not sustainable, but they are used to bears and often seek to explain and even excuse bear behaviour when conflict arises, says Dr. Salvatori.

She ran EU-funded workshops to try to improve co-existence with bears in Romania, with livestock owners, beekeepers, game managers, hunters, and small environmental organisations included in monthly meetings.

Normal

"The general attitude is that it is normal to have bears, but that encounters with bears should be better managed," Dr. Salvatori said. "There is no strong opposition to using hunting as a management tool, provided that it is not detrimental to their population." Also, people felt that bear tourism needed to be better regulated.

Her workshops generated various recommendations to avoid conflicts with bears and stop them raiding beehives and crops and killing livestock, such as securing bins in bear areas, and putting up electric fences in touristic spots.

Another, more individual, option highlighted by Dr. Hertel is hazing, where specific problem bears are targeted with rubber bullets or dogs to deter them from people.Scientists, animal activists: Don't cull Romanian brown bear

Provided by Horizon: The EU Research & Innovation Magazine

Panamanian field expeditions examine how species persevere in face of climate change

by Deborah Blackwell, Harvard University

Student researchers Ben Goulet-Scott (left), Sylvia Kinosian, and Jacob Suissa, reach the crest of a hill overlooking the Mamoní Valley Preserve while carrying 90 species of ferns on their backs. Credit: Ben Goulet-Scott/Harvard University Department of Organismic and Evolutionary Biology

Last month, two graduate students from the Arnold Arboretum of Harvard University traveled to one of the most species-rich landscapes in the world: a remote strip of tropical rainforest at the narrowest point in the Central American country of Panama.

Ben Goulet-Scott, a Ph.D. candidate in the Graduate School of Arts and Sciences' Department of Organismic and Evolutionary Biology (OEB) and a fellow in the Arboretum's Hopkins Lab, and Jacob Suissa, OEB Ph.D. candidate in the Friedman Lab at the Arboretum, hope their research in the Mamoní Valley Preserve in Panama will increase our understanding of how biodiversity can persevere in the face of climate change, deforestation, and human disturbance.

The 20-square-mile land conservancy on the isthmus separating Central and South America teems with life, making the condensed rainforest habitat a perfect location for their research project because of the vast number of known and potentially undiscovered species living there, Goulet-Scott said.

"New England has twice the land area of Panama, but half the number of bird species, and 10 times fewer reptiles and amphibians," he said. "This particular location contains species that migrate or move from north to south and get funneled into this very narrow area, concentrating an incredible amount of biodiversity."

The Mamoní Valley Preserve (MVP) Natural History Project is an ongoing series of student-led field expeditions, organized by Goulet-Scott in 2017. The project is designed to establish a baseline understanding of how the different land-use conditions within the preserve—from fully deforested cattle pasture to recovering secondary forest and intact primary forest—affect patterns of diversity.

Student members of the Mamoní Valley Preserve Natural History Project, Jacob Suissa (left), Sylvia Kinosian, Brian Vergara, Jose Palacios, and Christian López examine the rhizome vasculature of a fern species during their first collection trip in the rainforest. Credit: Harvard University

By bringing early career biologists like himself to the site for fieldwork, Goulet-Scott is building a list of species and observations to eventually make available in a central repository for scientists and researchers focused on conservation.

"Identifying every species there is actually probably not possible, but that's how we think about the mission of these trips," he said. "By bringing groups of students who have expertise in identifying different types of organisms, we work to document all the different species we see in each type of habitat."

Creating a baseline is vital because it will help determine which areas are of high priority for conserving certain species, and which species might already be threatened.

"It's an interesting exploration," Goulet-Scott said. "The more frequently we do biodiversity studies, the better we are able to track how conservation is going in this area."

The MVP Natural History Project intrigued Robert Brooker, M.B.A., who learned about Goulet-Scott's research and funded this expedition.

"I met Ben on a trip there a year ago and was excited about what he was doing and wanted to support it," said Brooker, the chairman of WIN-911 Software in Austin, Texas. "Ben and his colleagues are very interested in this work and I want to help a group of creative and intelligent students to accomplish whatever they want to accomplish to make the world a better place."

The trip in January was Goulet-Scott's third expedition for the project. The first, in 2017, included four doctoral students from Harvard, with a taxonomic focus on reptiles and amphibians. During the second trip in 2018, seven Harvard Ph.D. students and one from the University of Texas collected data on insects, specifically butterflies and moths.

This year's team—two Harvard Ph.D. students, one Harvard undergraduate, a Ph.D. student from the University of Utah, and three undergraduates from the University of Panama—investigated ferns, the second-most-diverse lineage of vascular plants behind flowering plants. Ferns are a focal point for Suissa, who investigated an ancient lineage of fern relatives as a research technician at the Smithsonian Institution Museum of Natural History in Washington, D.C. At Harvard he studies the evolution of the water transport system in ferns, which is a building block for the downstream analysis of climate change.

"Studying ferns in locations like the preserve furthers our understanding of global patterns of biodiversity and can help inform conservation practices in the future," he said. "We need to know what is where in order to protect it."

Suissa has done fieldwork in Costa Rica four times, but this was his first time in Panama, where there may be as many as 700 different species of plant in a 100 square kilometer region. He said this intense diversity in such a small space is an important educational opportunity for students studying tropical biology. Survey findings from each MVP expedition are also used to create educational materials such as field guides and brochures for the preserve, as well as for youth environmental education.

Christian Lopez, a graduate student in botany from the University of Panama, said he appreciated being part of this MVP Natural History Project expedition, on which he was able to find species he had never previously seen in the wild.

"This collaboration with Harvard University and its doctoral students has been a great learning opportunity for me, and the exchange of knowledge went both ways," he said.

Other team members included Jon Hamilton, environmental science and public policy; Sylvia Kinosian, Ph.D. candidate in biology, Utah State University; and Jose Palacios and Brian Vergara, undergraduate students studying biology at the Universidad de Panama. Goulet-Scott said one of the most exciting things about the MVP Natural History Project is that it is student-run.

"There's no one more experienced than a grad student involved, so it's all about being self-organized," he said. "We are in charge of figuring out all the logistics and planning how we're going to spend our day, what the goals of the trip are, and what equipment we need to bring."

Conducting field work in the rainforest is not for the weak of body or spirit. Sweltering heat and humidity, unpredictable weather, potential for infection, deadly snakes and spiders, and even the chiggers that burrow into waistbands and armpits can impact the best-prepared researcher. The team traveled in the beds of pickup trucks over unpaved, bumpy roads and through 15 river crossings. One of their trucks slid off of a riverbank and got stuck, partially submerged. Once a fallen tree blocked their passage until they helped local farmers chop it up with machetes.

The weeklong expedition included challenging hikes in pouring rain while carrying heavy packs full of equipment and trash bags full of plant specimens. The students hiked up a 900-meter mountain, felt their way through the wet cloud mist of an elfin forest, and bathed in a pristine waterfall. Suissa avoided stepping on a deadly fer-de-lance viper thanks only to one of the local guides. But his first trip to the neotropics as an undergraduate was enough to change the trajectory of his career.

Guide Gabriel Salazar takes a moment of rest overlooking the top of Cerro Brewster (Dianmayala) after a three-hour intense uphill hike. Credit: Harvard University

On this expedition, Suissa collected more than 100 fern stems, spanning their evolutionary tree. The group's efforts yielded 170 specimens and an estimated 160 species, including rare and hybrid ferns and lycophytes—unexpected and exciting findings for the researchers, Goulet-Scott said.

Lider Sucre, M.B.A., CEO of Mamoní 100 (one of the three organizations involved in protecting the Mamoní Valley), said the MVP History Project is a catalyst to bigger and deeper opportunities for the future of global science.

"For three years now we've been seeing that the Mamoní Valley Natural History Project that Harvard University students have led and been engaged with is an incredibly important part of how we give greater substance to the biodiversity that lives here," he said. "It is a unique keystone location matched by nothing else, a crossroads to so many lifeforms, and they have been incredibly lucky with their exceptionally rare finds with wildlife that is not usually seen."

Climate may play a bigger role than deforestation in rainforest biodiversity

Sea lions could point the way to monitor riverbed erosion

by City University London

A recent research study conducted by City, University of London's Professor Christoph Bruecker and his team, has revealed a novel correlation in the way sealions and rats use their whiskers, which paves the way for the online-monitoring underwater events which trigger riverbed erosion.

The Riverfly Conference, held at London's Natural History Museum on 20th March 2020 will bring together organisations and individuals participating in the Riverfly Partnership and the Anglers' Riverfly Monitoring Initiative (ARMI). The morning will focus on new developments in ARMI while the afternoon's theme will be about pressures on rivers and ways to mitigate them.

The research team has found that in the same way rats use their whiskers for detecting textures and hard surfaces on dry land, sea lion whiskers use their whiskers to detect swirling fluid elements—so-called vortices—in the flow of the water they move around in.

Using the specially equipped water tank in City's aeronautical engineering laboratory for sea lion simulations, Professor Bruecker and his team have mapped out the typical signatures used by sea lion whiskers to detect such vortices, which signal whether prey has swum into a region and allows the animal to track the path of their prey.

Professor Bruecker, City's Royal Academy of Engineering Research Chair in Nature-Inspired Sensing and Flow Control for Sustainable Transport and Sir Richard Olver BAE Systems Chair for Aeronautical Engineering, has published a study of his findings in Nature: Scientific Reports, in a paper titled "Seal and Sea lion Whiskers Detect Slips of Vortices Similar as Rats Sense Textures."

Professor Bruecker has transferred the idea of sea lion whiskers to arrays of bio-inspired optical flow sensors, which are submersible and can remotely monitor the vortices passing over the riverbed and can detect strong events that may trigger the erosion processes.

Having sought support from the Engineering and Physical Sciences Research Council (EPSRC), discussions are currently underway with the River Thames Restoration Trust to mark out and implement a test area on the Thames for the first tests of this monitoring system.

This research could make way for the online monitoring of the environmental impact of large cruiser vessels on the river bed in the shallow waters found near urban settlements such as London, Venice and Amsterdam, providing warnings of high flow speeds close to the riverbed.

Drones sensing by a whisker

More information: Muthukumar Muthuramalingam et al. Seal and Sea lion Whiskers Detect Slips of Vortices Similar as Rats Sense Textures, Scientific Reports (2019). DOI: 10.1038/s41598-019-49243-5

Brain imaging study reveals new clues about PTSD in victims of terrorist attacks

by Institut National de la Sante et de la Recherche Medicale

The terrorist attacks committed in Paris and Saint-Denis on November 13, 2015 have left lasting marks, not only on the survivors and their loved ones, but also on French society as a whole. A vast transdisciplinary research program, the 13-Novembre Project, is co-directed by Francis Eustache, neuropsychologist and director of the Inserm Neuropsychology and Imaging of Human Memory Laboratory and Denis Peschanski, historian and CNRS research director. It seeks the ongoing construction and evolution of the individual and collective memory of these traumatic events and to improve our understanding of the factors that protect against the development of post-traumatic stress disorder (PTSD).

Part of this program is a brain imaging study called Remember, which is focused on the cerebral networks implicated in PTSD. Its findings will be published in the journal Science on February 14, 2020. This study, which is sponsored by Inserm and led by Inserm researcher Pierre Gagnepain, shows that the untimely resurgence of intrusive images and thoughts in PTSD patients—a phenomenon long attributed to a deficiency of memory—is also linked to a dysfunction of the brain networks that control memory. The researchers expect that these findings will lead to the identification of new treatment options for PTSD sufferers.

Understanding more about the cause of intrusive memories

According to the traditional models of PTSD, the persistence of painful intrusive memories is caused by memory dysfunction—a bit like a scratched record playing the same fragments of our memories over and over again. From the anatomical point of view, such dysfunctions are particularly visible in the hippocampus—a key region for the formation of memory.

In addition, patients' attempts to suppress their traumatic memories have long been considered an ineffective mechanism. Instead of confronting these painful images in order to leave them in the past, the way they were trying to repress or drive them out was seen more as a negative strategy, intensifying the intrusions and worsening the situation of those with PTSD.

The brain imaging study published in the journal Science challenges some of these ideas, hypothesizing that the untimely resurgence of intrusive images and thoughts could also be linked to a dysfunction of the brain networks implicated in controlling memory (going back to the previous metaphor of the record player, the turntable arm is not working correctly). "These control mechanisms act like a regulator of our memory and are engaged in halting or suppressing the activity of the regions associated with memories, such as the hippocampus," Pierre Gagnepain explains.

Together with his colleagues, Gagnepain worked with 102 survivors of the Paris attacks, 55 of whom had PTSD. Also involved in the study were 73 people who had not been exposed to the attacks.

In order to model the resurgence of intrusive memories observed in the PTSD of these volunteers without putting them through the ordeal of viewing the shocking images of the attacks, the scientists opted for a brain imaging research protocol based on the Think/No-Think method (see box).

The aim of this method is to create associations between a cue word and an unrelated everyday object (for example, the word chair with the image of a ball), in order to reproduce the presence of an intrusion when confronted with the cue word. "Then we can study the capacity of the participants to drive and suppress from their mind the intrusive image that emerges against their will when confronted with the cue word," says Alison Mary, researcher and co-author of the article.

The researchers looked at the brain connections between the control regions located in the frontal cortex (at the front of the brain), and the memory regions, such as the hippocampus. They hoped to identify any differences among the three groups of participants (the first not exposed to the attacks, the second exposed but without PTSD, and the third also exposed but with PTSD).

The results show that the participants with PTSD present a deficiency of the mechanisms that suppress and regulate the activity of the memory regions during an intrusion (particularly the activity of the hippocampus).

Conversely, the functioning of these mechanisms is to a large extent preserved in the individuals without PTSD, who are able to fight the intrusive memories. "In our study, we suggest that the memory suppression mechanism is neither intrinsically poor nor responsible for the intrusions, as was previously believed. However, its dysfunction is. If we use the analogy of a car's brakes, it is not the act of applying them—or in our case the act of suppressing the memories—that poses a problem, but the fact that the braking system is faulty, which leads to their overuse," explains Pierre Gagnepain.

Many of the current PTSD therapies are aimed at recontextualizing the problematic memories, at making the patients aware that these memories belong in the past, and at reducing the feeling of fear that they generate.

Designing new interventions which are disconnected from the traumatic events and which stimulate the control mechanisms identified in this study could be a useful addition in training patients how to implement more effective mechanisms of suppression. "The current treatments all involve confronting the trauma, which is not always easy for the patients. It could be imagined that this type of task stimulates the mechanisms of suppression, thereby facilitating the processing of the traumatic memory in the traditional therapies," the researchers conclude.

Exposure to trauma impacts ability to squash bad memories

More information: "Resilience after trauma: The role of memory suppression" Science (2020). science.sciencemag.org/cgi/doi … 1126/science.aay8477

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