Tag Archives: endangered species

A big step toward producing rhino gametes

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To save the northern white rhinoceros from extinction, the BioRescue team is racing to create lab-grown egg and sperm cells of the critically endangered subspecies. The team has now reported a milestone in Science Advances: they have generated primordial germ cells from stem cells – a world’s first.

Thirty-three-year-old Najin and her daughter Fatu are the last surviving northern white rhinos on the planet. They live together in a wildlife conservancy in Kenya. With just two females left, this white rhino subspecies is no longer capable of reproduction – at least not on its own. But all hope is not lost: according to a paper published in the journal Science Advances, an international team of researchers has successfully cultivated primordial germ cells (PGCs) – the precursors of rhino eggs and sperm – from embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs).

The last two surviving females live in the Ol Pejeta Conservancy in Kenya./CREDIT:Jan Stejskal, Safari Park Dvůr Králové


The last two surviving females live in the Ol Pejeta Conservancy in Kenya./CREDIT:Jan Stejskal, Safari Park Dvůr Králové

This represents a major milestone in an ambitious plan. The BioRescue project, which is coordinated by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) and has been funded by the German Federal Ministry of Education and Research (BMBF) since 2019, wants to save the northern white rhino from extinction. To this end, the scientists are pursuing two strategies – one of them trying to generate viable sperm and eggs from the skin cells of deceased rhinos. The idea is to implant the resulting embryos into closely related southern white rhino females, who will then carry the surrogate offspring to term. And so the northern white rhino subspecies, which humans have already effectively wiped out through poaching, may yet be saved thanks to state-of-the-art stem cell and reproductive technologies.

First success with an endangered species

To get from a piece of skin to a living rhinoceros may be a true feat of cellular engineering, but the process itself is not unprecedented: the study’s co-last author Professor Katsuhiko Hayashi leads research labs at the Japanese universities of Osaka and Kyushu in Fukuoka, where his teams have already accomplished this feat using mice. But for each new species, the individual steps are uncharted territory. In the case of the northern white rhinoceros, Hayashi is working in close cooperation with Dr. Sebastian Diecke’s Pluripotent Stem Cells Technology Platform at the Max Delbrück Center and with reproduction expert Professor Thomas Hildebrandt from Leibniz-IZW. The two Berlin-based scientists are also co-last authors of the current study.

“This is the first time that primordial germ cells of a large, endangered mammalian species have been successfully generated from stem cells,” explains the study’s first author, Masafumi Hayashi of Osaka University. Previously, it has only been achieved in rodents and primates. Unlike in rodents, the researchers have identified the SOX17 gene as a key player in rhinoceros PGC induction. SOX17 also plays an essential role in the development of human germ cells – and thus possibly in those of many mammalian species.

The southern white rhino embryonic stem cells being used in Japan come from the Avantea laboratory in Cremona, Italy, where they were grown by Professor Cesare Galli’s team. The newly derived northern white rhino PGCs, meanwhile, originated from the skin cells of Fatu’s aunt, Nabire, who died in 2015 at Safari Park Dvůr Králové in the Czech Republic. Diecke’s team at the Max Delbrück Center was responsible for converting them into induced pluripotent stem cells.

Next step: cell maturation

Masafumi Hayashi says that they are hoping to use the cutting-edge stem cell technology from Katsuhiko Hayashi’s lab to save other endangered rhino species: “There are five species of rhino, and almost all of them are classified as threatened on the IUCN Red List.” The international team also used stem cells to grow PGCs of the southern white rhino, which has a global population of around 20,000 individuals. In addition, the researchers were able to identify two specific markers, CD9 and ITGA6, that were expressed on the surface of the progenitor cells of both white rhino subspecies. “Going forward, these markers will help us detect and isolate PGCs that have already emerged in a group of pluripotent stem cells,” Hayashi explains.

The BioRescue scientists must now move on to the next difficult task: maturing the PGCs in the laboratory to turn them into functional egg and sperm cells. “The primordial cells are relatively small compared to matured germ cells and, most importantly, still have a double set of chromosomes,” explains Dr. Vera Zywitza from Diecke’s research group, who was also involved in the study. “We therefore have to find suitable conditions under which the cells will grow and divide their chromosome set in half.”

Genetic variation is key for conservation

Leibniz-IZW researcher Hildebrandt is also pursuing a complementary strategy. He wants to obtain egg cells from 22-year-old Fatu and fertilize them in Galli’s lab in Italy using frozen sperm collected from four now deceased northern white rhino bulls. This sperm is thawed and injected into the egg in a process known as intracytoplasmic sperm injection (ICSI). However, Hildebrandt explains that Fatu is not able to bear her own offspring, as she has problems with her Achilles tendons and cannot carry any additional weight. Her mother Najin, meanwhile, is past child-bearing age and also suffers from ovarian tumors. “And in any case, since we only have one donor of natural eggs left, the genetic variation of any resulting offspring would be too small to create a viable population,” he adds.

The team’s top priority, therefore, is turning the PGCs they now have at their disposal into egg cells. “In mice, we found that the presence of ovarian tissue was important in this crucial step,” Zywitza explains. “Since we cannot simply extract this tissue from the two female rhinos, we will probably have to grow this from stem cells as well.” The scientist is hopeful, however, that ovarian tissue from horses could come in useful, as horses are among the rhinos’ closest living relatives from an evolutionary standpoint. If only humans had taken as good care of the wild rhino as they had of the domesticated horse, the immense challenge now facing the BioRescue scientists could perhaps have been avoided altogether.

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Clarifying the chaos of narwhals behavior; what are narwhals, how they help [Details]

Sound reveals ‘Ocean giants’ dance with wind to find food

Sound reveals ‘Ocean giants’ dance with wind to find food

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A study by MBARI researchers and their collaborators published today in Ecology Letters sheds new light on the movements of mysterious, endangered blue whales. The research team used a directional hydrophone on MBARI’s underwater observatory, integrated with other advanced technologies, to listen for the booming vocalizations of blue whales. They used these sounds to track the movements of blue whales and learned that these ocean giants respond to changes in the wind.

Along California’s Central Coast, spring and summer bring coastal upwelling. From March through July, seasonal winds push the top layer of water out to sea, allowing the cold water below to rise to the surface. The cooler, nutrient-rich water fuels blooms of tiny phytoplankton, jumpstarting the food web in Monterey Bay, from small shrimp-like krill all the way to giant whales. When the winds create an upwelling event, blue whales seek out the plumes of cooler water, where krill are most abundant. When upwelling stops, the whales move offshore into habitat that is transected by shipping lanes.

“This research and its underlying technologies are opening new windows into the complex, and beautiful, ecology of these endangered whales,” said John Ryan, a biological oceanographer at MBARI and lead author of this study. “These findings demonstrate a new resource for managers seeking ways to better protect blue whales and other species.”

CREDIT:Image: Goldbogen Lab/Duke Marine Robotics and Remote Sensing Lab (NMFS Permit 16111)

The directional hydrophone is a specialized underwater microphone that records sounds and identifies the direction from which they originate. To use this technology to study blue whale movements, researchers needed to confirm that the hydrophone reliably tracked whales. This meant matching the acoustic bearings to a calling whale that was being tracked by GPS. With confidence in the acoustic methods established, the research team examined two years of acoustic tracking of the regional blue whale population.

This study built upon previous research led by MBARI Senior Scientist Kelly Benoit-Bird, which revealed that swarms of forage species—anchovies and krill—reacted to coastal upwelling. This time, researchers combined satellite and mooring data of upwelling conditions and echosounder data on krill aggregations with the acoustic tracks of foraging blue whales logged by the directional hydrophone.

“Previous work by the MBARI team found that when coastal upwelling was strongest, anchovies and krill formed dense swarms within upwelling plumes. Now, we’ve learned that blue whales track these dynamic plumes, where abundant food resources are available,” explained Ryan.

Blue whales recognize when the wind is changing their habitat and identify places where upwelling aggregates their essential food—krill. For a massive animal weighing up to 150 tonnes (165 tons), finding these dense aggregations is a matter of survival.

While scientists have long recognized that blue whales seasonally occupy Monterey Bay during the upwelling season, this research has revealed that the whales closely track the upwelling process on a very fine scale of both space (kilometers) and time (days to weeks).

“Tracking many individual wild animals simultaneously is challenging in any ecosystem. This is especially difficult in the open ocean, which is often opaque to us as human observers,” said William Oestreich, previously a graduate student at Stanford University’s Hopkins Marine Station and now a postdoctoral fellow at MBARI. “Integration of technologies to measure these whales’ sounds enabled this important discovery about how groups of predators find food in a dynamic ocean. We’re excited about the future discoveries we can make by eavesdropping on blue whales and other noisy ocean animals.”

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Clarifying the chaos of narwhals behavior; what are narwhals, how they help [Details]

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Researchers have used the mathematical equations of chaos theory to analyse the data from long-term monitoring of an electronically tagged narwhal. They have extracted previously undetected diurnal patterns within what initially appeared to be irregular diving and surface resting behavior, using records extending across 83 days.

“While animal-borne ocean sensors continue to advance and collect more data, there is a lack of adequate methods to analyse records of irregular behavior,” says Hokkaido University geophysicist Evgeny A. Podolskiy, first author of the research published in the journal PLOS Computational Biology.

Podolskiy developed the procedure to find behavioral patterns in seemingly intractable complexity with Mads Peter Heide‐Jørgensen at the Greenland Institute of Natural Resources.

Narwhals (Monodon monoceros) are relatively small whales found in Arctic seas, famous for their long single tusks and called the unicorns of the sea. They are one of the most endangered Arctic species due to climate change, human activity, and predation by such invasive species as killer whales. The narwhals are notable for undertaking dives to extreme depths of more than 1,800 metres. Their life cycle is tightly coupled with sea ice, which is rapidly declining.

A pod of adult male narwhals, Greenland, September 2019 (Photo: Carsten Egevang; This image may exclusively be used in relation to this press release. The image can not be included in media archives for use apart from the above and not be handed over to third parties, without prior acceptance by the photographer)./CREDIT: Carsten Egevang

Podolskiy and Heide‐Jørgensen combined their expertises in signal processing and biologging to understand the full diversity of behaviors of a satellite-tagged narwhal. Mathematical techniques developed as part of chaos theory can interpret complicated and seemingly chaotic behavior in dynamic systems to reveal states called ‘attractors’, which the systems tend to develop towards. In essence, the approach identifies significant patterns that would otherwise be difficult to detect.

The analysis of the behavior of the electronically tagged narwhal, inspired by Podolskiy’s previous work on turbulence, revealed a daily pattern of activity and how it was affected by changing seasons, features of narwhal behavior that were previously unrecognised. The animal rested nearer to the surface around noon, but when they did dive at that time the dives were very deep. During twilight and at night the dives became more shallow but also more intense, possibly due to hunting for squid, which is known for diurnal vertical migration. It was also found that increased sea ice constrains the narwhal’s surface activity, and is correlated with more intense diving.

“Our approach is relatively simple to implement and can map and label long term data, identifying differences between the behavior of individual animals and different species, and also detecting perturbations in behavior caused by changing influences,” the authors suggest.

The researchers expect that their new method may be especially useful for assessing the challenges to narwhals and other Arctic animals posed by climate change and the loss of sea ice. Such information may prove vital in adopting policies to protect endangered species in the face of natural change and increased human activity.

Related: http://dx.doi.org/10.1371/journal.pcbi.1010432

J

More than 1.1 million sea turtles poached over last three decades: Study

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One of the most serious threats to wildlife biodiversity, in addition to the climate crisis, is the illegal killing and trafficking of animals and plants. Despite many laws against the black-market wildlife trade, it is considered to be one of the most lucrative illicit industries in the world.

Animals, especially endangered and threatened species, are often exploited and sold for their pelts or used as medicine, aphrodisiacs, curios, food and spiritual artifacts.

In a new study published in Global Change Biology, Arizona State University researchers estimate that more than 1.1 million sea turtles have been illegally killed and, in some cases, trafficked between 1990 and 2020. Even with existing laws prohibiting their capture and use, as many as 44,000 sea turtles were exploited each year over the past decade in 65 countries or territories and in 44 of the world’s 58 major sea turtle populations.

Hawksbills turtle/Photo:en.wikipedia.org

Despite the seemingly large number of poached turtles, the study shows that the reported illegal exploitation of sea turtles declined by approximately 28% over the last decade —something that surprised the researchers. They initially expected to see an overall increase in reported poaching.

“The decline over the past decade could be due to increased protective legislation and enhanced conservation efforts, coupled with an increase in awareness of the problem or changing local norms and traditions,” says Kayla Burgher, co-first author of the study and a doctoral student in ASU’s environmental life sciences program in the School of Life Sciences.

In addition to the slight decline, the researchers found that most of the reported illegal exploitation over the past decade occurred in large, stable and genetically diverse sea turtle populations.

Jesse Senko, co-first author of the study and an assistant research professor with the ASU School for the Future of Innovation in Society says this discovery may be a silver lining to the high number of turtles illegally exploited. “What this means is that most of these sea turtles came from healthy, low-risk populations, which suggests that, with a few exceptions, current levels of illegal exploitation are likely not having a major detrimental impact on most major sea turtle populations throughout the world’s oceans.”

Sea turtle/Photo:en.wikipedia.org

Our assessment also did not include eggs or turtle products, such as bracelets or earrings made from sea turtle shells that could not be easily attributed to individual turtles,” says Senko.

The study revealed additional patterns and trends that may assist in determining conservation management priorities. For example, Vietnam was the most common country of origin for illegal sea turtle trafficking, while China and Japan served as destinations for nearly all trafficked sea turtle products. Similarly, Vietnam to China was the most common trade route across all three decades.

Across the 30-year study period, 95% of poached sea turtles came from two species — green and hawksbill turtles — both of which are listed under the U.S. Endangered Species Act. Also, Southeast Asia and Madagascar emerged as major hotspots for illegal sea turtle take and trade, particularly for critically endangered hawksbills, which are prized in the illicit wildlife trade for their beautiful shells.

“Our assessment is an important foundation for future research and outreach efforts regarding illegal sea turtle exploitation. We believe this study can help conservation practitioners and legislators prioritize conservation efforts and allocate their resources to best help protect sea turtle populations from harmful levels of exploitation worldwide,” says Burgher.

The research team says much more needs to be done to sustain global biodiversity.

“Increased support for governments lacking the resources to protect sea turtles is needed, along with support for communities to sustain human well-being in the face of restrictions or bans on sea turtle exploitation. We must develop conservation strategies that benefit both people and turtles,” says Senko.

Mysterious 350-ft ‘blue hole’ off Florida reveals huge wealth of undersea life

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Blue holes, or underwater sinkholes similar to sink holes on land, are scattered across Florida’s Gulf continental shelf though vary in size, shape and depth, but most are rich in ecological diversity with  plants and animals. NOAA-supported project has come out with new findings of one such blue hole called Amberjack Hole.

Last year, in May and September, a team of scientists from Mote Marine Laboratory, Florida Atlantic University/Harbor Branch, Georgia Institute of Technology and the U.S. Geological Society, with support from the NOAA Office of Ocean Exploration and Research, explored one blue hole, dubbed “Amberjack Hole,” approximately 30 miles off west of Sarasota shore.

They deployed divers and a “benthic lander” with scientific instruments collectively weighing more than 270 kilograms (600 pounds into Amberjack Hole, whose bottom extends deeper than 107 meters (350 feet). The team documented life around the rim of the hole and carbon, nutrients, and microscopic life throughout the hole and in its bottom sediments.

The benthic lander was deployed to the bottom of Amberjack Hole to collect data and samples for longer periods than divers can, right where the bottom water meets the sediment. Image courtesy of Mote Marine Laboratory

What Can We Learn?

From this “mission,” scientists are hoping to learn whether these submersed sinkholes are connected to Florida’s groundwater or if there is groundwater intrusion into the Gulf of Mexico. If a particular blue hole is secreting nutrients and thus affecting an area’s primary production or whether such microenvironments harbor unique or new species of microbes. If the Amberjack site should become a protected area or not is the next on agenda.

The rim of Amberjack Hole is 34 meters (113 feet) from the surface, and the rest of the hole extends down another 72+ meters (237 feet)! In May 2019, scientific divers traveled to the bottom of Amberjack Hole and deployed a special benthic lander created for this project to s depth where bottom water meets the sediment.

In September, the team returned with 17 water samples from just outside the hole down to the bottom and collected 4 sediment cores at the bottom. Remarkably, they also discovered two dead but intact smalltooth sawfish, Pristis pectinata, an endangered species, at the bottom of the hole. One of the animals was subsequently recovered to undergo a necropsy.

The deceased sawfish were intact enough to be collected for research, and Mote scientists quickly reported the discovery to NOAA and the Fish and Wildlife Conservation Commission and obtained the required permit for collection of one of the sawfish, a male measuring an impressive 12 feet long. Video courtesy of Mote Marine Laboratory.

 

A diver’s view looking up to the opening of Amberjack Hole. Image courtesy of Mote Marine Laboratory

Water sampled inside the hole was found to contain naturally occurring isotopes of radium and radon, two markers of groundwater, suggesting that blue holes are not isolated from groundwater and could provide insights into potential groundwater connection between the Floridan Aquifer and the Gulf of Mexico.

Further, in August 2020 and May 2021 a second deeper site, Green Banana, will be explored using the same techniques developed for the Amberjack Hole. The first trip is scheduled for August 2020, and work will continue in 2021.

 

Crocodiles Set to Face Extinction, Says Australian Researcher

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An estuarine crocodile, also known as a “saltie”.

Many of the world’s 27 species of crocodylians will soon be either totally or locally extinct due to human population expansion and intensive land-use for agriculture depleting the water bodies, which provide succour to crocs, said a University of Queensland researcher.

Emeritus Professor Gordon Grigg of UQ says the fact that these reptiles had survived millions of years was no good owing to current rate of human expansion and encroachment of natural resources. “The current human population level and its magnitude and rate of resource consumption are unprecedented,” Professor Grigg said.

Only those crocs living in remote wetland habitats in which humans see no benefit may survive into the future, he said. Some crocodylians might have already become extinct if not for active conservation management undertaken in the second half of the 20th Century.

“For some species, the incentive for conserving them has been the commercial value of their hides, but that is dependent upon its use in high fashion garments and accessories, and that is a somewhat fragile foundation,” he said.

On flip side, the rising temperatures and sea levels may turn a more positive note for crocodylians, as it may create more habitat that will be suitable for any species to survive the human onslaught, he said wryly.

The largest living crocodiles, the estuarine or saltwater crocodile (Crocodylus porosus), are found in Northern Australia and can grow to six metres and weigh more than 900 kilograms.

Professor Grigg said estuarine crocodiles, also known as Indo-Pacific crocodiles or “salties”, were one of the luckier species because human populations across Australia’s north were unlikely to increase significantly in the next few decades.  They might be among the survivors.

Professor Grigg and illustrator and biologist David Kirshner, in their recent book, Biology and Evolution of Crocodylians, reviewed the biology of the crocodiles, alligators, caimans and gharials, and also discusses the great diversity of their gigantic extinct ancestors, some of which were probably warm-blooded.