Ecology

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Botos use clicks and whistles to communicate with each other and to find prey.Credit: Sylvain Cordier/Gamma-Rapho via Getty

Researchers have used artificial intelligence (AI) to map the movements of two endangered species of dolphin in the Amazon River by training a neural network to recognize the animals’ unique clicks and whistles.The findings, published in Scientific Reports on 27 July1, could lead to better conservation strategies by helping researchers to build an accurate picture of the dolphins’ movements across a vast area of rainforest that becomes submerged each year after the rainy season.Using sound is much less invasive than conventional tracking techniques, such as the use of GPS tags, boats or aerial drones.
Saving the Amazon: how science is helping Indigenous people protect their homelands
“Sound is probably the only sense that we know of that we all share on Earth,” says co-author Michel André, a bioacoustician at the Technical University of Catalonia in Barcelona, Spain.André and his colleagues wanted to explore the activity of two species, the boto (Inia geoffrensis) — also known as the pink river dolphin — and the tucuxi (Sotalia fluviatilis) across the floodplains of the Mamirauá reserve in northern Brazil. The researchers placed underwater microphones at several sites to eavesdrop on the animals’ whereabouts.To distinguish the dolphin sounds from the noisy soundscape of the Amazon, they turned to AI, feeding the recordings into a deep-learning neural network capable of categorizing sounds in real time, “exactly as we do with our own brain”, says André.Using this technology, researchers can analyse volumes of information “that would otherwise be almost impossible”, says Federico Mosquera-Guerra, who studies Amazonian dolphins at the National University of Colombia in Bogotá.The AI was trained to identify three types of sound: dolphin, rainfall and boat engines. Both dolphin species use echolocation clicks almost constantly to sense their environment, and they communicate to others by whistling. Detecting these clicks and whistles enabled the researchers to map the animals’ movements. Botos and tucuxis have distinct whistles, so the neural network could distinguish between the species.Conservation effortsThe study is a part of a collaboration between the Technical University of Catalonia and the Mamirauá Institute of Sustainable Development in Tefé, Brazil, which aims to use this technology for monitoring the Amazon’s biodiversity and threats to it.
AI empowers conservation biology
Both dolphin species are endangered: estimates suggest that the boto population is declining by 50% every ten years, and the tucuxi population every nine years2. Monitoring when and where the animals move will allow researchers to help protect their populations and come up with measures to help “Indigenous communities to cohabitate with the presence of dolphins”, says André. Dolphins can disrupt fisheries across the floodplains, for example, by competing for fish or becoming tangled in nets.Mosquera-Guerra says that collecting such information is “fundamental” to inform decisions on conservation across the Amazon region.In future, the team wants to train the neural network to detect other aquatic species, and to deploy the system over a wider area. The same approach could also be used in the ocean. André’s previous work using this system has shown the effects of human-made noise pollution on sperm whales, and has enabled the development of a warning system for ships to help avoid the animals3. More

Helmeted hornbills (Rhinoplax vigil) eat fruit and so are key to seed dispersal. Over-trading in this species is likely to damage its native ecosystem.Credit: Tim Plowden/Alamy

Every year, more than 100 million plants and animals are traded legally and illegally around the world. But whether this is sustainable remains hotly debated by researchers. A study published on 26 July in Nature1 sheds some light on the issue by creating a global map of ecosystems’ resilience to current levels of wildlife trade.The findings could help to show conservation scientists and policymakers where to focus resources, by identifying the hotspots where wildlife trade could cause the most damage.
Major wildlife report struggles to tally humanity’s exploitation of species
“It’s one thing to say, ‘we know that trade is unsustainable’,” says study co-author Oscar Morton, a conservation biologist at the University of Sheffield, UK. “It’s another thing to say, ‘we know what happens to ecosystem X when we take out species A’.”For example, he says more than one million tokay geckos (Gekko gecko) — small, colourful lizards common in southeast Asia — are traded every year as pets. But whether that volume of trade is sustainable is unknown.Whole-ecosystem effectsWhen measuring the overall sustainability of the wildlife trade, individual species cannot be considered in isolation, says Morton. Yet it’s so complex to analyse the impact of the industry on ecosystems as a whole that few attempt it.Morton and his colleagues addressed this gap by collating data on the legal trade in birds and mammals collected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and legal and illegal trade from the International Union for Conservation of Nature (IUCN). The researchers overlaid this information on maps of the distribution of various species across the world.

Source: Ref 1.

They added data on the phylogeny of species — their evolutionary histories — to indicate whether each has unique traits (See ‘Hotspots of uniqueness’). They also included information about the species’ functional role in the ecosystem — for example, whether it is a large predator or a tiny grazer. “In a healthy ecosystem, you want a wide range of traits, because then they do all of your ecosystem services — so seed dispersal, carbon stocking, pest control,” says Morton.The resulting maps allow the team to visualize the potential impact of removing a species from an ecosystem.For example, hornbill birds are heavily traded for their casques, the bony protrusions on their upper beaks. But as large fruit-eaters, the birds have a key role in seed dispersal in their ecosystems. If hornbills were to be depleted from an area, the vegetation would change radically, with knock-on effects for the birds, insects and other animals that inhabit the ecosystem, says Morton.Damaging tradeThe map revealed global hotspots where trade has the most potential to damage, that is, ecosystems where functional and evolutionary diversity was high. “It’s an impressive piece of research that brings together a huge amount of data,” says Vincent Nijman, a specialist in wildlife trade at Oxford Brookes University, UK. He says the map clearly shows that in relatively small areas of the world, the industry could put ecosystems at risk. He points to parts of Africa and southeast Asia as being important hotspots.
Ivory hunting drives evolution of tuskless elephants
“If we were to be able to pay more attention” to regulating trade in those regions, says Nijman, “then we’re going to get a much better return on our investment”.International and domestic policies should require assessments of the impact of the wildlife trade on entire ecosystems, says Morton. “We should be looking at ecosystem sustainability as well as species sustainability, when we talk about trade sustainability,” he says.As well as playing a part in their ecosystems, many species have intrinsic scientific value, says data scientist Mike Massam at the University of Sheffield, a co-author of the study. “We don’t want to lose millions and millions of years of evolutionary history.” More

Last month, I led a team in the thrilling discovery of a deep-sea octopus nursery on underwater mountains, only the fourth such location known in the world. It was incredible to witness octopuses being born, their tiny pink tentacles springing to life. Worryingly, any day now, the International Seabed Authority (ISA) could green-light mining for metals and rare-earth elements in habitats such as these.Between 10 and 21 July, ISA’s council met in Kingston, Jamaica, to hash out a code of rules for deep-sea mining in international waters. Interest in exploiting the deep sea is exploding thanks to its deposits of cobalt, nickel, rare-earth elements and other metals that are used in key green-energy technologies such as electric-vehicle batteries, solar panels and wind-turbine magnets. ISA, an intergovernmental body tasked by the United Nations with regulating deep-sea mining while ensuring the protection of the marine environment, missed a 9 July deadline to finish the code. Now, commercial mining applications could be submitted to ISA even though the code is not complete, which raises many legal issues that its council is rushing to try to resolve.
Deep-sea mining could soon be approved — how bad is it?
The code would be a legally binding document defining: how environmental-impact assessments must be done; the thresholds for harm to the marine environment; how inspection, monitoring and enforcement would occur; and how the benefits of mining would be shared equally between countries.In my view, it is impossible to effectively protect, monitor for harm or restore these ecosystems without a basic understanding of their biology. Some of the sought-after minerals are found in lumps called nodules that form on the sea floor over millions of years. Mining them currently requires scraping large tracts of sea bed, which is destructive and indiscriminate.For the two weeks of the ISA meeting, I fielded hundreds of daily messages while providing expert scientific guidance to delegations in my capacity as a contributor to the Deep-Ocean Stewardship Initiative.I told the delegations that the world knows too little about deep-sea ecosystems to judge what rules would ensure their protection. It is difficult to even convey the immense scale of our knowledge gaps. Deep-sea corals — like trees on land — are keystone species in their habitats, providing crucial structure for other forms of life. Scientists don’t really know how these corals reproduce: spawning has never been documented. How can we restore a baseline that we have never observed? We need research covering at least ten years for each habitat to be able to make evidence-based decisions.Mining will affect animals, such as corals, that are attached to the sea bed and microorganisms that provide crucial ecosystem services, such as carbon fixation and nutrient recycling. It will affect the entire water column above the sea floor, generating plumes of debris as well as noise and light pollution that could affect migratory species, including commercially important animals such as tuna. The deep sea is a repository for immense genetic diversity that could yield new scientific insights.There is irreplaceable scientific value in some deep-sea ecosystems, such as the Lost City field of hydrothermal vents near the Mid-Atlantic Ridge, with its towering ‘cathedrals’ of carbonates. Its unique chemistry and microbiology yield clues about how life evolved on Earth and whether it might exist on other planets.
The global fight for critical minerals is costly and damaging
Restoration is commonly used in land-based mining to make up for harm caused. But the deep sea operates on a profoundly slower timescale than ecosystems on land, and there is no evidence that restoration would work as a mitigation strategy. Forests can be replanted, but there is no current evidence that deep-sea habitats could be repaired on human timescales after extensive damage. In fact, studies suggest that natural restoration of deep-sea ecosystems and their services will probably take thousands to millions of years.Proponents of deep-sea mining argue that it causes less environmental damage and has fewer human impacts than does mining on land, but it is not yet possible to know the effects on the deep sea, let alone compare them with those of land-based mining. Besides, this argument seems a false dichotomy to me. Deep-sea mining will not replace mining on land — both types will probably continue.I think that the urgent need for critical minerals should further spur innovation instead of leading to irreplaceable deep-sea ecosystems being wiped out. Nations should boost investment in battery chemistry research, which shows promise for reducing the need for these materials, and in reuse and reclamation programmes for the metals already extracted that are currently destined to sit in landfill.It’s not just hundreds of scientists around the world — including me — who are calling to pause mining in the deep sea because of the lack of understanding of these ecosystems. Twenty countries support a pause or moratorium, including Brazil, Canada, Germany and New Zealand, and France supports a ban. Major companies including Google, Microsoft, BMW and Volkswagen have pledged not to buy or finance deep-sea minerals until the supply chain meets environmental, social and governance standards.When I was an undergraduate student two decades ago, deep-sea mining was discussed as if it were science fiction, not likely to happen in my lifetime. I hope it stays in the realm of fiction. We have much better options for the future of our society and our planet. More

Research suggests that some seaweed might have health benefits for people, including helping to protect against cancer, diabetes and other diseases. Extreme temperatures, light and water salinity can boost the levels of compounds behind these effects.As a fisheries engineer at the Sheep Breeding Research Institute in Bandırma, Turkey, I research the chemistry of marine organisms, including seaweeds and molluscs, and their potential for farming. In this picture, taken this year, I’m collecting seaweed samples near Horseshoe Island in Antarctica on an expedition funded by the Turkish government. With our collaborators at the Çanakkale Onsekiz Mart University in Turkey, we aim to identify species, analyse their chemical compositions and determine their chemical processes that are associated with health benefits.The only other study of seaweed diversity near the island was in 1976, which identified six species (R. L. Moe & T. E. DeLaca Antarct. J. 11, 20–24; 1976). We think we have found more than 15, including some that had been recorded only in other parts of Antarctica. Diversity near the island could have changed because climate change and glacier melt have altered light levels, brought in more fresh water and provided new nutrients.We are analysing these samples for antioxidants, chlorophyll and other compounds — as well as proteins, lipids and amino and fatty acids — because they affect the extent of protection against disease.Last year, we increased antioxidant compounds in Gongolaria barbata, a common brown seaweed, by changing how much light it received and the salinity of the water in which we grew it (I. Ak et al. Phycologia 61, 584–594; 2022). Seaweed extracts are already used in the production of food supplements, such as omega-3.It might one day be possible to farm Antarctic seaweed species containing a lot of compounds that improve human wellness, just by altering growing conditions. More

Sarah Batterman talks frankly about her experience of sexual harrassment at the Smithsonian Tropical Research Institute. Its director Josh Tewkesbury describes steps taken to protect staff.

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In late 2021 a BuzzFeed investigation revealed a catalogue of sexual misconduct incidents at the Panama-based Smithsonian Tropical Research Institute (STRI). Ecologist Sarah Batterman, one of more than a dozen women to speak out about their experiences, describes what happened to her and the impact it has had on her career.Batterman, who filed a formal complaint to the institute in 2020 after being contacted by other women with similar experiences of harassment and abuse at STRI, tells Adam Levy: “It was almost 10 years of a lot of pain after what happened, which made a lot of my research really difficult. I estimate that I lost three of the 10 years in productivity.”Josh Tewkesbury joined STRI as its director in July 2021, five months before the BuzzFeed story broke. He describes the measures taken to safeguard scientists from sexual harassment and assault since its investigation concluded.“We have been working with the people that came forward for the BuzzFeed article, engaging them in the process of how we make STRI a more safe place. ” he says. “We’ve been just overwhelmed and really thankful with the degree to which those individuals have, have been willing to engage.”This episode is part of a Working Scientist podcast series about freedom and safety in science. More

Increasing human presence in and around Bidoup Nui Ba National Park has resulted in more frequent wildfires.Credit: Evgeniya Pavlova/Getty

The first centuries-long analysis of wildfires in southeast Asia has been compiled using tree rings from a region in central Vietnam. There has been a drastic increase in the frequency of wildfires in the area over the past 100 years, but climate change is not the primary culprit. Instead, humans lighting fires for agriculture are behind the rising number of forest burns, according to the study1 published in Geophysical Research Letters.“Fire has a big impact on the forest structure,” says Thiet Nguyen, a forest ecologist and PhD student at the University of Melbourne in Australia. “There’s a very high level of biodiversity in that forest.”Many people think of tropical Vietnam as lush with jungle, but in the central highlands, misty montane forests are home to around 100,000 hectares of conifers mixed with broadleaf trees. Whereas tropical trees don’t tend to put on annual growth rings because they grow consistently year-round, the conifers have annual cycles of growth. Nguyen and his colleagues took cross-sections from recently fallen trees of two species, Pinus kesiya and Keteleeria evelyniana, at 12 locations in Bidoup Nui Ba National Park and counted the tree rings back over almost 400 years.When trees are exposed to non-lethal fires, their bark chars, leaving behind a burn scar within the tree rings. The team dated the earliest definite fire scar to 1772. Between then and 1905, only 17% of years contained clear fire scars, although Nguyen admits that the farther they went back in time, the smaller was the available number of samples, reducing their confidence in the findings. After 1905, they had good clear tree rings to work with. From then until 1963, 71% of years showed scars from fires, however the fires often affected only a small number of sites. But from 1964 to the present day, fire has occurred almost every year, often affecting a larger number of sites.‘A big problem’Until the advent of this study, “we had no idea how the fire regime has been changed”, says Nguyen. “If the fires are increasing rapidly, that can reduce biodiversity and forest density,” he adds. “It’s a big problem.”Using statistical analysis, the authors looked for relationships between fires, climate and the human population. They discovered that historically, fire patterns were associated with climate; data from Pacific sea surface temperatures (see ‘Forests on Fire’) showed that weather patterns such as El Niño and La Niña, which determine dry or wet years, could have influenced how much combustible plant material was available and how dry and flammable it was, for example.But after 1963, according to population estimates for the nearby city, Da Lat, an increasing number of people came to live in the area. Humans use fire to clear land for agriculture, Nguyen says, and fire probably spreads to the national park — established in 2004 — from nearby areas. People also start fires in the park. From 1964, the authors found that the signal from humans overwhelmed climate as the driving force behind the fires.

The fires’ increasing frequency, coupled with heightened fire conditions brought on by climate change, will be a problem in the future, says Brendan Buckley, a dendrochronologist at Columbia University in New York, who was a master’s programme adviser to Nguyen but was not involved in this study. “There might very well be some burning that gets out of control in these areas that are protected rainforest.”Understanding historical and modern fire occurrence is crucial because it gives researchers a baseline to work from, helping forest managers to prepare for climate change, Buckley says. Although fire can be beneficial to a coniferous forest, the rainforest is a totally different ecosystem and can be destroyed by fire, he says.Nguyen says that the species used in this study are common across other parts of southeast Asia, such as Thailand and the Philippines, meaning that the same technique could be used to explore fire history and climate change in other countries.“If we had this kind of study in other countries in southeast Asia, a big historical fire reconstruction for the region, that would be cool.” More

When the peace deal opened Colombia up, scientists were not the only groups to take advantage. People returned to tend their land and now, in some places, there are tensions between conservation and farming. In the Sumapaz paramo, government attempts to demarcate a conservation zone have led to disputes.
More-industrialized farming — of oil palm and livestock for example — is spreading. It laps at the edges of the Guásimos forest where Toro lives. Meanwhile, people are making the most of their new-found access to Colombia’s rich supplies of tropical wood, coal, oil and gold. Colombia lost 128,000 hectares of primary forest in 2022. Furthermore, illegal coca plantations are appearing in record numbers.
Meanwhile, violence persists, involving groups such as gangs of ex-combatants, drug traffickers, paramilitaries and those guerrilla groups that have not made peace deals with the government.
“Pretty much every single crisis that you can think about in the world, you have it in Colombia right now,” says Diazgranados.
As a result, research trips can be stressful and require elaborate safeguards. When Diazgranados went to explore a region of El Cocuy National Park in the northeast where, as far as he knows, no scientists had ever been, the government insisted on sending in elite armed forces to the study area two weeks beforehand to prepare the way; then, with two days to go before the trip, another military cordon formed inside the first one.
He and his team of 40 Colombian and international scientists snatched 4 days of collecting before their protection ended, and they had to leave. They found 14 new plant species that Diazgranados thinks are new to science, but he left with a heavy heart: the landscape was not the untouched wilderness he had hoped to find. “The local farmers have been trashing the ecosystem,” he says.
Despite these experiences, scientists do find that their work in the past seven years has seeded a sense of wonder among local people about the plants and animals they live alongside, especially when people discover that they are living in the only place in the world to host some of these species. Some residents have learned scientific skills. When Torres’s phone rings these days, it is often a villager asking for help in identifying a species, or advice on how best to deal in an ecologically sensitive way with problems such as an animal attacking their crops. Sometimes they even want contacts in a government ministry to help to solve some environmental problem, or they have new range information to report for a species studied during Santander Bio.
“They developed an identity,” says Torres of the communities he has met. “And once you have that identity, people are not going to just destroy their habitat — because they have connected with it.”

Author: Aisling IrwinPhoto editor: Jessica HallettArt editor: Jasiek KrzysztofiakSubeditor: Richard LimEditor: Kerri Smith

Map credits:
Protected areas: IGACElevation: GEBCO.Species data: https://cifras.biodiversidad.co/colombiaEcosystems: Adapted from Fig. 1 of Ref. 2Caecilia pulchraserrana photo: Felipe Villegas/SantanderBIO/Humboldt InstituteTrichomycterus rosablanca photo: Felipe Villegas/ColombiaBIO – Minsciencias/Humboldt InstituteAtlapetes blancae photo: Gabbro/Alamy

References
Zhang, C. et al. ISPRS J. Photogramm. Remote Sens. 169, 280–291 (2020).Gori, B., Ulian, T., Bernal, H. Y. & Diazgranados, M. Sci. Rep. 12, 7835 (2022).Mesa, L. M., Lasso, C. A., Ochoa, L. E. & Donascimiento, C. Biota Colombiana 19 (Suppl. 1), 95–116 (2018).Florez, J. S., Cadena, C. D., Donascimiento, C. & Torres, M. Zool. J. Linn. Soc. 193, 772–788 (2021).

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