Ecology

Australia’s iconic Great Barrier Reef is fundamentally changing because of repeated bleaching from high ocean temperatures brought on by climate change, according to marine biologists.“It’s not a question of reefs dying or reefs disappearing, it’s reef ecosystems transforming into a new configuration,” says marine biologist Terry Hughes, from James Cook University in Townsville, Australia.“Species like fish and crustaceans and so on — the iconic biodiversity of reefs — all depend on the structure and three dimensionality the habitat provided by corals,” Hughes says. “When you lose a lot of corals, it affects everything that’s dependent on corals.”Corals ‘bleach’ when stressed, expelling their colourful resident zooxanthellae. According to a report released on 17 April by the Great Barrier Reef Marine Park Authority – the Australian government’s reef management agency — the World Heritage-listed reef is experiencing its worst mass bleaching event on record. The Reef Snapshot said three-quarters of the entire reef is showing signs of bleaching and nearly 40 percent is showing high or extreme bleaching.The report is based on aerial surveys of 1,080 of the Great Barrier Reef’s estimated 3,000 individual reefs, and in-water surveys of a smaller number of reefs.It showed that while bleaching was observed along the entire length of the Great Barrier Reef, it was most severe in the central and southern regions.“We’ve never seen this level of heat stress across all three regions of the Great Barrier Reef,” says Brisbane-based marine biologist Lissa Schindler, from the Australian Marine Conservation Society.This is the fifth mass bleaching event on the Great Barrier Reef in eight years. Hughes warns that climate change-driven increases in ocean temperatures are making it more difficult for the Reef’s corals to recover between bleaching events. “In the last six years, we’ve settled into bleaching every other year – in 2020, 2022, and now 2024 – and that’s simply not enough time for a proper recovery,” he says.Global phenomenonThe Snapshot was one of a series of reports released this week on coral bleaching that also sounded alarm bells for reefs. The Australian Institute of Marine Science announced on 18 April that the Great Barrier Reef experienced water temperatures in parts of the southern reef at 2.5 degrees Celsius higher than historical summer peaks.Meanwhile on 15 April the United States’ National Oceanic and Atmospheric Administration declared the fourth global coral bleaching event on record, and the second in the past decade. The declaration acknowledges that the warmth of the southern hemisphere summer mirrored coral bleaching events seen in the northern hemisphere summer last year.It comes as global sea surface temperatures again broke records in 2023, associated with a strong El Niño weather pattern, recording an annual average temperature around 0.3 degrees Celsius higher in the second half of 2023 compared with 2022.“There have been very high temperatures driven by climate change all across the world, and there has been coral bleaching in many other countries,” says environmental scientist Roger Beeden, chief scientist for the Great Barrier Reef Marine Park Authority, Townsville.Hughes says the warming climate is pushing reefs to have less coral, and the mix of coral species is changing. For example, the branching and table-shaped corals are often the fastest to recover from a bleaching event because they are fast-growing, Hughes says. However they’re also very prone to bleaching and have higher levels of mortality during bleaching events.“It’s a bit analogous to a fire on land through a forest, that favours a bounce-back by flammable grasses before the trees can recover,” he says. “Ironically, that that bounce-back, that resilience, undermines the ability of the reef to cope with the next inevitable bleaching event.” Seaweeds also flourish when corals degrade.Beeden says those who live and work on the Reef are observing significant changes. “There’s historical photos that show inshore reefs that were laden with coral, and that’s very different now,” he says.He says there are an estimated 450 different species of coral on the Reef, and such diversity means there is a chance the Reef will adapt to the changing conditions, even if it changes character. “What we see within species is definitely there is variability in how they respond to stress events.”Hughes says the solution to the Great Barrier Reef’s bleaching problem is clear. “Reduce greenhouse gas emissions. Full stop.” More

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More than three months into 2024, politicians in Brazil are still at odds about how much money the country’s research institutes and federal universities will receive this year. Scientists say that unless more funding is found, they won’t have enough money to cover basic expenses such as water, electricity and financial aid for students.On one side of the bargaining table is the National Congress. In December, it imposed cuts to the 2024 budget for the country’s research and higher-education institutions, which have already had their funding slashed several times in the past decade.On the other side is the administration of President Luiz Inácio Lula da Silva, which is fighting to reverse some of the congressional cuts. Lula, as the leader of the leftist Workers’ Party is popularly known, took office in 2023 pledging to make science a priority, increase Brazil’s spending on research and eliminate deforestation.“We should be doing research to support conservation policies, but now we are in a situation where we don’t know if we will be able to cover our routine activities,” says Nilson Gabas Júnior, director of the Emílio Goeldi Museum in the Amazonian city of Belém, whose studies provide data that feed into the management of the Amazon rainforest.Although the cuts affect the entire country, the Amazon institutions argue that they are the hardest hit because their federal support is already disproportionately low.Temporary reprieveLula managed to increase the budget for science and technology in 2023, compared with the levels in 2022, and scientists had hoped that funding would at least remain stable in 2024. Instead, Congress, which is controlled by a conservative majority, slashed the 2024 budget of the Ministry of Science, Technology and Innovation, which funds Brazil’s 16 federal research institutes, by 6.8% compared with that in 2023. Congress also reduced the budget for higher education from 6.3 billion reais (US$1.24 billion) in 2023 to 6.0 billion reais in 2024.After the budget was passed, an organization that represents the interests of the 69 Brazilian universities supported by the federal government published an open letter calling for more funding. Scientists’ allies in Congress have also tried to persuade legislators to reconsider their decision.In March, the government and Congress reached an agreement to restore 250 million reais to federal universities’ funding. But Sylvio Mário Puga Ferreira, dean of the Federal University of Amazonas in Manaus, who was involved in the negotiations, points out that “it would take a funding increase of 2.5 billion reais just to bring the universities’ budget closer to 2017 levels”.Winner take allThe paltry funding for federal universities and research institutes is likely to exacerbate an already-grim situation for science in Brazil’s Amazon. Data from the National Council for Scientific and Technological Development (CNPq), Brazil’s largest government agency for research funding, indicate that only 4% of the money invested in research projects in 2023 was directed to institutions in the seven states classified as the North region, which encompasses 87% of the Brazilian Amazon.“Scientific activity in Brazil is heavily concentrated in a few education and research institutions in the South and Southeast” regions, says Odir Dellagostin, president of the Brazilian National Council of State Funding Agencies. “They boast the best graduate programs, produce and publish more research and offer the best job opportunities” — and receive the most funding.
‘We are killing this ecosystem’: the scientists tracking the Amazon’s fading health
The problem extends to biodiversity research. A study1 analysing CNPq’s investments in projects in botany, zoology, ecology and limnology (the study of freshwater ecosystems) between 2016 and 2022 found that research groups from the North region received only 2.57 million reais during this period. “This situation leaves the region with a very limited capacity to respond to the threats the forest faces,” says Lis Stegmann, one of the study’s authors and a biologist at the Eastern Amazon branch of the Brazilian Agricultural Research Corporation (Embrapa), in Belém. CNPq did not respond to Nature’s request for comment.Institutions in the North region produce fewer — and lower-quality — research outputs than do those in the South and Southeast regions, in part because they have difficulty training and attracting highly qualified personnel, and getting funding. In 2022, the seven Amazon states accounted for 3.9% of Brazil’s scientific production, whereas the state of São Paulo alone accounted for 28.9%, according to an unpublished study by Dellagostin.Funding feedback loopThis leads to a self-perpetuating problem: decisions about who gets research funding in Brazil are based heavily on quantitative assessments. Scientists who produce more research and publish in high-impact journals have better chances of acquiring funding.“Amazon research institutions are caught in a vicious circle,” says Emmanuel Zagury Tourinho, dean of the Federal University of Pará. “They don’t have enough funding because they lack robust scientific production, but they also cannot develop their research capacity because they don’t have enough funding.” This has led to a situation in which researchers from São Paulo (around 3,000 kilometres away from the Amazon) receive more public funding to study Amazon biodiversity than do researchers who are actually located in the Amazon.Some scientists are still hopeful that they will get some extra funds this year. “We are talking to the [science] minister Luciana Santos about the possibility of additional budget allocations for the upcoming months,” Gabas says. The most likely scenario, however, is that this discussion will be postponed until the next budget, because some of the funds that were earmarked for science and education in 2024 have already been redirected. More

“When I first came to the small Caribbean island of Carriacou in 1990, I had no intention of staying. But something clicked; my partner and I have been here ever since.I’m from Venice, Italy, so a small island feels cosy to me. We also thought that Carriacou was small enough to tackle environmental problems and help make a difference. We saw the overfishing, deforestation and environmental damage here — not by multinational corporations, but by local people who were unaware of the ecological consequences of their actions.Since starting an environment and education foundation, called KIDO, in 1995, we have run around 30 projects — from protecting sea turtles to replanting mangroves.In this photograph, I am hiking to our latest project, the 40-hectare Anse La Roche nature reserve. Deforestation affected several areas of the plot, and one spot was devastated, illegally, with a bulldozer. To reconstitute the forest’s eroded soil, we gather Sargassum seaweed — overgrowth of which is afflicting Caribbean beaches as the sea warms — and use it as fertilizer.We will also plant thousands of native trees, including replanting 20 key canopy tree species that have almost been lost from Carriacou. This might be the last chance to save the forest: Carriacou’s diminishing rainfall is our nemesis, and each day we water around 3,000 saplings.With another ten years of care, we will see the forest resurge. Today when it rains, water rushes down the hillsides, taking the topsoil with it — but once the trees are established, rainwater will be caught in the natural terracing across the slope that the formidable buttress-root systems create. Forests take decades to grow, and it will be somebody else sitting under those trees saying, ‘Wow, it’s much cooler here!’” More

Selfish Genes to Social Beings: A Cooperative History of Life Jonathan Silvertown Oxford Univ. Press (2024)The fact that all life evolved thanks to natural selection can have depressing connotations. If ‘survival of the fittest’ is the key to evolution, are humans hardwired for conflict with one another? Not at all, says evolutionary biologist Jonathan Silvertown in his latest book, Selfish Genes to Social Beings. On the contrary, he argues, many phenomena in the natural world, from certain types of predation to parasitism, rely on cooperation. Thus “we need no longer fret that human nature is sinful or fear that the milk of human kindness will run dry”.Silvertown uses examples from genes, bacteria, fungi, plants and animals to emphasize that cooperation is ubiquitous in nature. For instance, bacteria called rhizobia thrive in the root nodules of legumes — and turn nitrogen from the air into a soluble form that the plants can use. Some beetles cooperate to bury animal corpses that would be too large for any single insect to manage alone, both reducing the risk of other animals stealing food and providing a nest for beetle families to live in.
It’s time to admit that genes are not the blueprint for life
And many bacteria indicate their presence to each other using a chemical-signalling system called quorum sensing, which is active only when members of the same species are tightly packed together. This allows each cell to adjust its gene expression in a way that benefits the individuals in the group — to release a poison to kill other species, for instance, when enough bacteria are clustered together to mount a decent attack.Even eighteenth-century piracy, says Silvertown, is a good example of effective cooperation. Pirates worked together on their ships, and used violence more often against outsiders than as an internal mechanism for law enforcement.The author argues against the idea that cooperation is fundamentally at odds with competition — a view that emerged as a consequence of the sociobiology movement of the 1970s, in which some biologists argued that all human behaviour is reducible to a Darwinian need to be the ‘fittest’. The reality, as Silvertown shows, is not black and white.

Lichen is a composite organism, in which an alga lives within a fungus.Credit: Ashley Cooper/SPL

A matter of perspectiveTake lichens, for instance — ‘composite organisms’ in which an alga or cyanobacterium lives within a fungus. The Swiss botanist Simon Schwendener, who discovered this relationship in the 1860s, argued that a lichen is a parasite: “Its slaves are green algals, which it has sought out or indeed caught hold of, and forced into its service.” Another way to view the relationship is that these algae and fungi are co-dependent — when they co-exist as a lichen, each grows better than it would alone. The line between parasitism and mutualism, competition and cooperation is not clear cut. It’s a matter of perspective.
A ‘user’s manual for the female mammal — how women’s bodies evolved
Similarly hazy boundaries are found in the biology of our own cells. More than a billion years ago, cells absorbed bacteria, which eventually evolved into structures called mitochondria that generate energy. Mitochondria are an essential part of the cells of all plants, animals and fungi alive today. They could be considered slaves, with cells the parasites. Or perhaps they are more like adopted family members.Fundamentally, Silvertown proposes, cooperation in each of these situations stems from selfishness. Animals did not evolve to act for the benefit of their species, but to spread their own genes. Cooperation happens because mutual benefits are better, biologically speaking, than working alone, as the case of lichens effectively demonstrates.If this seems heartless, it’s a reflection of the human tendency to apply human moral frameworks to biological phenomena. The use of emotionally charged words such as ‘slave’ and ‘adopted’ takes us away from rigorous science and leads us to see biological interactions as ‘good’ or ‘bad’, rather than as the morally agnostic, transactional processes that they truly are.
Why reciprocity is common in humans but rare in other animals
The anthropomorphizing of biological processes is a deep and current problem. The tendency to falsely imply agency in the natural world is an easy trap to fall into — consider how often people might say that a virus such as SARS-CoV-2 ‘wants’ to be transmitted, for instance, or that ants act ‘for the good of their colony’. I would have liked to hear more about Silvertown’s views on this category error. But in places, I felt that he could have made his implied understanding more explicit. Instead, he sometimes sacrifices that carefulness for unnecessary jokes, noting, for instance, that bacteria “are essentially singletons who like to party”.The author could also have talked more about how the amorality inherent in most of the natural world does not apply to humans. Similarly to other organisms, our evolutionary heritage makes us social, but whether that sociality is ‘good’ or ‘bad’ is a moral, not a scientific, question. This distinction from the other cooperative processes that Silvertown outlines could have been explained better.Selfish Genes to Social Beings is at its best in the long, fascinating discussions of the complexity of cooperative behaviours across the natural world. For instance, although I’ve read a lot about biology, before reading this book I could never understand how RNA chains might have joined together and started the process of self-replication through which all life evolved. Silvertown can talk as easily about the compounds making up your genes as most people can about yesterday’s football match. More

NEWS AND VIEWS
02 April 2024

The complexity of fitting brakes to all four wheels of a car and the simplicity of John Maynard Smith’s ecological models, in the weekly dip into Nature’s archive. More

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