Ecology

NEWS AND VIEWS
08 October 2024

Lynx numbers ebb and flow as these predators hunt hares across Alaska, but analysis suggests that this population wave is mediated by survival rather than by how lynx disperse. More

Scientists have started swabbing short-tailed Shearwater (Ardenna tenuirostris) for evidence of bird flu. The birds are migrating from the northern hemisphere to Australia.Credit: John Holmes/Alamy

Australia and the rest of Oceania are the last regions free of the highly pathogenic strain of bird flu that has caused mass mortality in birds across the world and a massive outbreak in dairy cattle in the United States. Why animals in the southern region have so far escaped infection is a mystery, but scientists have several theories.For one, Australia is geographically isolated and doesn’t import live poultry, says Frank Wong, a virologist at the CSIRO Australian Centre for Disease Preparedness in Geelong. Many of the countries’ birds are endemic and do not migrate to regions where the virus is spreading.But the virus’s arrival in Australia is “a matter of when, not if”, says Michelle Wille, a virologist at the Centre for Pathogen Genomics at the University of Melbourne, Australia.Bird surveyWille thinks that long-distance migratory shorebirds and seabirds that come from Siberia and Alaska through southeast Asia to Australia are most likely to carry the virus into the country.This week, Australian scientists, including Wille, started swabbing the first of nearly 1,000 migratory birds for the virus. Over the coming weeks, the team will capture wedge-tailed shearwaters (Ardenna pacifica) and short-tailed shearwaters (Ardenna tenuirostris) as they migrate from the northern autumn to the southern spring. At night, shearwaters sleep in burrows and are relatively easy to grab. The researchers will swab the birds for the virus, and take blood to test for antibodies that will reveal previous exposure. They will be testing for the H5N1 clade 2.3.4.4b in particular, which has caused mass mortality in birds and some mammals.To swab the birds, the researchers will travel to seven locations across Australia, as far apart as Broome in the northwest, Lord Howe Island in the east and Phillip Island in the south.Deadly ducks?Wille says another possible route for the virus is through ducks. Scientists think migrating ducks and geese in other parts of the world can spread the disease without succumbing to it.That’s because ducks’ epithelial cells have a sensor, known as RIG-I, that detects an invading influenza virus and triggers an immune response that usually fends it off. Kirsty Short, a virologist at the University of Queensland in Brisbane, says ducks might have evolved such defences in Asia from repeated infections with many less-pathogenic forms of the virus, giving them pre-existing immunity. Although they don’t get sick from H5N1, they can still pass it on, and ducks congregate in lakes and ponds with other birds, increasing the chances of disease spread.Isolated ecosystemsAnother reason that Oceania is currently free of the virus is that the region’s ducks are endemic and they don’t tend to migrate overseas.This isolation is partly explained by a biogeographical division called the Wallace Line, first described by naturalist Alfred Russel Wallace in 1859, which runs through Indonesia. Many animal species tend to stay on one side of the line or the other, and because of this isolation, the fauna on each side are distinct. Michael Andersen, an evolutionary biologist at the University of New Mexico in Albuquerque describes this phenomenon as “one of the great mysteries” of the world.The sharp division might also mean that the virus is not adapted to animals east of the Wallace Line, says Wong. “Avian influenza viruses, including this high-pathogenicity avian influenza virus, are particularly well-adapted to certain species,” he says. Birds in Australia could have a genetic make-up that circumvents the usual infection route for the virus, but no one has yet tested this hypothesis.Although many duck species are short-distance migratory birds and tend not to cross the Wallace Line, some species — including Pacific black duck (Anas superciliosa) and spotted whistling duck (Dendrocygna guttata) — do, and Wille thinks they could introduce H5N1 to the region.If the virus is detected, government veterinarians will immediately move in to cull the affected population, which happened when H7N3 and H7N9 strains of the flu were detected in Victoria in May.Short says that, when it happens, the effect on Australia’s birds, mammals and ecosystems is unknown, but many species are probably susceptible. “It’s a big research gap,” she says. More

Hummocks of moss cover Ardley Island off the tip of the Antarctic Peninsula.Credit: Dan Charman

A fast-warming region of Antarctica is getting greener with shocking speed. Satellite imagery of the region reveals that the area covered by plants increased by almost 14 times over 35 years — a trend that will spur rapid change of Antarctic ecosystems.“It’s the beginning of dramatic transformation,” says Olly Bartlett, a remote-sensing specialist at the University of Hertfordshire in Hatfield, UK, and an author of the study1, published today in Nature Geoscience, that reports these results.From white to greenBartlett and his colleagues analysed images taken between 1986 and 2021 of the Antarctic Peninsula — a part of the continent that juts north towards the tip of South America. The pictures were taken by the Landsat satellites operated by NASA and the US Geological Survey in March, which is the end of the growing season for vegetation in the Antarctic.To assess how much of the land was covered with vegetation, the researchers took advantage of the properties of growing plants: healthy plants absorb a lot of red light and reflect a lot of near-infrared light. Scientists can use satellite measurements of light at these wavelengths to determine whether a piece of land is covered by thriving plants.The team found that the area of the peninsula swathed in plants grew from less than one square kilometre in 1986 to nearly 12 square kilometres in 2021 (see ‘An icy land goes green’). The rate of expansion was roughly 33% higher between 2016 and 2021 compared with the four-decade study period as a whole.

Source: Ref. 1

“These numbers shocked us,” says Thomas Roland, a study co-author and an environmental scientist at the University of Exeter, UK. “It’s simply that rate of change in an extremely isolated, extremely vulnerable area that causes the alarm.”The research is “really important”, says Jasmine Lee, a conservation scientist at the British Antarctic Survey in Cambridge, UK. Other studies2,3 have found evidence that vegetation on the peninsula is changing in response to climate change, “but this is the first study that’s taken a huge-scale approach to look at the entire region”, she says.Previous visits by the authors to the peninsula lead the authors to think that most of the vegetation is moss. As mosses spread to previously ice-covered landscapes, they will build up a layer of soil, offering a habitat for other plant life, Roland says. “There’s a huge potential here to see a further increase in the amount of non-native, potentially invasive species,” he says.

Moss covers rocks on Norsel Point, an arm of an island off the Antarctic Peninsula.Credit: Dan Charman

This is a concern because Antarctica’s native flora are adapted to extreme conditions, and they might not be able to compete with an influx of other species, Lee says.The researchers point to climate change as the driver of the landscape’s shift from white to green. Temperatures on the peninsula have risen by almost 3°C since 1950, which is a much bigger increase than observed across most parts of the planet. The “phenomenal” rate of expansion of greenery, Roland says, highlights the unprecedented changes that humans are imposing on Earth’s climate. More

“I’ve always felt a connection with the ocean. I completed my PhD, on seabirds’ movement decisions, at the University of Milan in 2022. The following year, I joined the Institute for Environmental Protection and Research (ISPRA) at Ozzano dell’Emilia, Italy, as a researcher. In this photograph, taken in 2021, I was on an expedition that forms part of a collaborative project between ISPRA and the University of Milan. Its aim is to track the sea movements of European storm petrels (Hydrobates pelagicus).My colleagues and I had travelled to the caves on Foradada Island off the northwestern coast of Sardinia, which is a popular nesting site for the birds. It’s hard to get there: you arrive on a small boat, before climbing through the cave in the picture to reach the main chamber. Here, field assistant Danilo Pisu (on the right) and I are fitting petrels with tiny GPS loggers before returning them to their eggs. The birds have a distinctive smell, which everyone describes differently. To me, they have the slightly dusty scent of an old book.For thousands of years, humans have lived around the coastline of the Mediterranean Sea, and because of this it’s heavily polluted. We wanted to find out where the storm petrels range over the sea, and why, so that we could protect them better in this area.We found that the birds are attracted to parts of the sea where the water churns from currents meeting far below the waves. This creates a phenomenon that brings plankton up to the surface.Out of all the birds I have studied, these are the most interesting. They have a history of myth and mystery. In nineteenth-century folklore, seafarers believed them to be the spirits of dead sailors, who brought storms to ships. In reality, the birds were seeking shelter near the boats in bad weather. Having a deeper understanding of them makes them even more special.” More

Workers for the Billion Oyster Project prepare to place juvenile oysters in a waterway running through New York City.Credit: Diana Cervantes/Redux/eyevine

New York CityAs the Sun dropped behind the Statue of Liberty on Saturday, a staff member for a conservation group unlocked a gate on a nearby island to reveal the ingredients for a potential oyster renaissance: stacks of ‘reef balls’, large domes made of oyster shells and concrete. They will soon be placed in tanks filled with free-swimming oyster larvae. Once the larvae latch onto the balls and mature, the structures will be submerged in the murky waters off New York City in an effort to revive a lost ecosystem.Coastlines around the globe were once protected by oyster reefs, expansive masses of oysters that had fused to rocks and each other. Overharvesting and habitat loss have demolished about 85% of Earth’s oyster reefs in the past two centuries. But bringing them back could help coastlines to become more resilient to the effects of climate change, including intense storms and erosion, scientists say.
Can floating homes make coastal communities resilient to climate risk?
The Billion Oyster Project, a non-profit organization in New York City, is leveraging the bivalve’s engineering skills to slowly build a living breakwater. After a decade of refining the process, the project is generating know-how for other efforts that it has inspired elsewhere.“The foundations are there to rebuild these ecosystems, and there are considerable environmental and social benefits of doing this,” says Melanie Bishop, a marine ecologist at Macquarie University in Sydney, Australia. But it is still unknown1 whether restored reefs can grow large enough to buffer coastlines, and oyster-restoration proponents acknowledge that it will take an untold number of transplanted oysters and many years before reefs can provide a bulwark against rising seas.Mass of molluscsCenturies ago, New York Harbor, which lies between the five boroughs of the city — Manhattan, Staten Island, Brooklyn, the Bronx and Queens — and parts of New Jersey, was home to a massive conglomeration of eastern oysters (Crassostrea virginica) spanning nearly 900 square kilometres. Demand for the succulent molluscs skyrocketed as the city’s population boomed; at the same time, pollution in the harbour escalated, and by 1927, the oyster-reef ecosystem had collapsed.The Billion Oyster Project seeds oyster beds at 18 sites around New York City. Its goal: to initiate the reef-building process. If the oysters can consistently reproduce on their own, they could one day form a structure that buffers against hurricanes and extreme storms while protecting the shoreline from eroding into the rising sea, says Asly Ventura, a public-outreach coordinator for the project. Studies have found that oyster reefs boost biodiversity2 and can improve water quality3, which could create safe havens for other species as ocean conditions change.The larval molluscs need to settle onto hard, stable surfaces to grow. To provide a home for them, the project staff and volunteers mix crushed oyster shells, donated by restaurants, with recycled concrete, and use the slurry to make hollow, domed structures pocked with holes that are roughly one metre in diameter. Staff drop several of these domes at the project’s reef sites each summer, with the goal of forming vast shoals of oysters at each site.

Domed structures called reef balls are stored in New York City. They will be lowered into the nearby waters to provide a home for young oysters.Credit: Alix Soliman/Nature

The campaign has had mixed success. Of the 122 million oysters that were transplanted into the harbour by the end of last year, about half have died. “We do expect a large amount of die-off,” Ventura says. Oysters produce a lot of young because so many larvae die, she says. In 2022, the organization reported that oysters were naturally reproducing at about half of the installations.Pollution could partially explain why the molluscs aren’t multiplying on their own at every site. After it rains, a combination of raw sewage and stormwater is piped into the harbour. Lingering industrial waste contributes to poor water quality. Noise pollution could also be interfering with the larvae’s ability to find a suitable place to settle, because they use auditory clues to locate existing reefs, Ventura says.Ray Grizzle, a marine biologist at the University of New Hampshire in Durham, who has done scientific assessments for the project, says that juvenile oysters mostly settle within 400 metres of their parent reef. As a result, oysters might not self-seed readily at sites far from existing reefs.Grizzle’s greatest concern is how pathogens, such as the parasites Haplosporidium nelsoni and Perkinsus marinus, might affect oysters over the long term. “They’re down to about a 3- to 5-year lifespan now, when historically it was probably 10 to 20,” he says. When the lifespan is reduced, so is the population’s ability to form lasting vertical reef structures, he says. All the same, the project is “moving in a good direction”, Grizzle says.Reef resurgenceOther restoration projects are taking off around the world. In Australia, biologists attracted oysters simply by dropping limestone boulders onto a sandy sea bed. Larval flat oysters (Ostrea angasi) naturally settled on the rocks in densities that far exceeded expectations2, suggesting the larvae are travelling from unknown remnant reefs or oyster farms.“We didn’t know we were going to get any natural recruitment when we started,” says study co-author Dominic McAfee, a marine biologist at the University of Adelaide in Australia. The effort is meant to sustain the seafood industry and has increased the biodiversity of invertebrates at the site.In the North Sea, researchers are placing oyster larvae on the granite boulders at the base of wind turbines in an effort to fortify the structures and increase biodiversity.Bishop says that for oyster-reef projects to be successful, they need to be located in areas where the issues that led to their demise are no longer present, constructed to withstand predicted changes to the ecosystem and monitored for much longer than two to three years. Although there is a long way to go, “there is a lot of hope”, she says. More

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As a student in China in the late 1980s, I spent several wonderful semesters studying zoology and botany. I vividly remember the joy of a summer field trip, immersed in taxonomy and biodiversity, where I learnt about a weed called goose-grass. Its well-developed root system makes it difficult to pull out of the soil — earning it the nickname the ‘Dunzhao donkey’, because those attempting to extract it look like exhausted donkeys squatting on the ground.Taxonomy is crucial for biodiversity conservation — if we can’t properly identify animals, plants and fungi, we can’t find ways to preserve them. But since my student years, working as an ecologist in Shandong, China, I’ve witnessed a decline in the teaching of this important subject. Credit hours for botany and zoology modules have halved at many universities in China. The length of field trips has been reduced owing to lack of funding.
No basis for claim that 80% of biodiversity is found in Indigenous territories
It’s a similar story worldwide. Funding for projects involving taxonomy dropped drastically in the United Kingdom in the 1990s, replaced by those using molecular biology and genetics. Taxonomists in Europe worry that they themselves are becoming an endangered species, with retiring experts often not being replaced. And some low- and middle-income countries (LMICs), including tropical nations that contain some of the world’s biodiversity hotspots, have long faced a shortage of domestic talent.Decades on, and the costs of these cuts are now apparent. Biodiversity initiatives are struggling to find specialists. For example, in China, hundreds of surveys of animals, plants and fungi are under way, with the aim of improving the conservation of native habitats and species. But many organizers have found it difficult to recruit qualified researchers. Qiao Gexia, an entomologist at the Chinese Academy of Sciences in Beijing, has voiced concern that, as current taxonomists retire, there will be a reduction in studies of important taxa — such as termites, which are crucial to ecosystems but also can damage buildings, roads and bridges, and earwigs, which are useful for pest control but are detrimental to fruit production (see go.nature.com/3msjcxh).Indeed, a lack of taxonomic knowledge, especially at the local level, is leading to errors. For example, in 2022, a common fish in Xiaoqing River, China, was mistakenly reported to be an endangered species, causing confusion among conservationists and the public.
Harrowing trends: how endangered-species researchers find hope in the dark
If taxonomic knowledge is not maintained, it will become harder to prevent species becoming extinct.That’s why I feel it’s so important that the Kunming Biodiversity Fund — aimed at supporting global biodiversity conservation — includes a substantial pot of money for biodiversity education. The fund was launched in Beijing in May. Its co-chairs, the Chinese government and the United Nations Environment Programme, hope that the initial investment of 1.5 billion yuan (US$210 million) from China will attract other countries, institutes and organizations to invest in the fund. The money will be used to help LMICs meet the goals of the Kunming–Montreal Global Biodiversity Framework, which has been agreed on by almost 200 countries. The framework sets out 23 targets to be reached by 2030 and 4 goals for 2050, all of which aim to see humans living in harmony with nature.The first projects to be supported by the Kunming fund are expected to be announced before the start of the COP16 UN biodiversity conference on 21 October, at which progress towards meeting the biodiversity framework targets will be discussed and evaluated. As yet, education has not been mentioned as a focus — but I think it should be.I would like to see 10% of the Kunming fund’s annual budget put aside for education. It’s crucial to build up taxonomic know-how in LMICs that lack it, and to ensure that it is preserved in those where it might be dwindling.One priority should be funding programmes in LMICs that teach students taxonomic methods, such as observation of specimens, and modern techniques for assessing the biodiversity of animal and plant communities.
Can floating homes make coastal communities resilient to climate risk?
Laying camera traps and analysing the footage, for instance, is often cheaper, easier and requires fewer people than using live traps does. Analysis of DNA gathered from soil, water or air can be used to accurately assess the species in a local community, without the need to spot them all in the wild. And training in the use of online digital herbaria and collection galleries will enable young scientists to share knowledge and resources across countries.Universities can support this endeavour by incentivizing biodiversity and taxonomy courses for their students, perhaps by giving them more credits. And they should also offer general courses in taxonomy and biodiversity to students outside the biological sciences, to build awareness.Some might argue that a focus on direct conservation efforts is the best way for the Kunming fund to help achieve the framework’s 2030 targets. But education is the key to reaching many of those goals, especially because those living in a particular country are the ones best placed to understand its flora and fauna.Ignoring education will waste the Kunming fund’s resources. There can be no sustainable support for global conservation efforts without generation after generation of properly educated specialists. A lack of expertise will be devastating for the estimated one million species facing extinction worldwide today. More

The US National Wilderness Preservation System, created by the Wilderness Act of 1964, was a profound invention. In his review of Sophie Yeo’s book Nature’s Ghosts, Douglas Erwin trivializes the legislation’s origin as forester Aldo Leopold’s ‘pragmatic’ solution to allow undisturbed hunting (Nature 632, 974–975; 2024).
Competing Interests
The author declares no competing interests. More