Ecology

I grew up in Salzburg, Austria, and was always very fond of mountaineering. During my PhD, I used satellite data to measure the ice flow of large and remote glaciers in Iceland and polar regions that couldn’t be accessed in the field. This helped me study how quickly glacial ice flows. The subject fascinated me, and I decided to pursue a career in which I could travel to and study the glaciers in person instead of spending my days in front of a computer screen.In October 2021, on a fieldwork trip to the Jamtalferner glacier near Galtür, Austria, my colleagues and I found this big, beautiful cave in the middle of the glacier. In this photo, I’m inside the cave. In the background, there are bubbles of 300-year-old air trapped in the ice. It’s quite unusual for glaciers to be hollow, so I was curious about how the cavities formed.During the trip, we discovered that the cavities were much larger than we expected, especially compared with those that had already been documented.
Who wants to be a polar bear?
This glacier has been studied extensively since 1892. I go there with my colleagues about once every three weeks to measure the ice ourselves: it is melting rapidly. We are seeing changes not only in the glacier’s mass, but also where local plant species grow. For instance, certain plants and trees have begun to appear in regions that had previously been covered by glacial ice.On this trip, we figured out how large the cavities were. At that time, the cave was already showing signs of collapse, and by June 2022, it was completely gone.In glaciology, there is often no way to determine the precise conditions of an earlier time. A glacier might look the same from the outside, but it changes constantly inside: ice flows down and melts, snow cover grows and subsides. You can never come back to the exact same glacier; we can observe only the now. More

An excavating machine on the Japanese research vessel Hakurei collected cobalt-rich ocean sediments in a 2020 test run.Credit: Kiyoshi Ota/Bloomberg via Getty

Commercial mining of the sea floor could soon get the green light. The International Seabed Authority (ISA), a body associated with the United Nations that oversees deep-sea mining in international waters, is now meeting in Kingston, Jamaica, where it could decide whether companies can begin excavating the sea floor for minerals and metals such as cobalt, nickel and sulfides.Proponents say that this move could help with meeting the growing demand for rare-earth metals used in batteries both for electric cars and for storing renewable energy, aiding the shift to a low-carbon economy. However, research hints that the potential ecological impacts of deep-sea mining are larger than previously thought. Nature explores just how bad deep-sea mining could be.What’s the evidence for the effects of deep-sea mining on marine life?Scientists say that very little is known1 about deep-sea ecosystems, making it difficult to assess how they will be affected by mining. However, a few new studies are providing clues to the damage that large-scale mining might cause.A study2 published today in Current Biology is the first to examine the environmental effects of mining cobalt-rich crusts. These rock-hard, metallic layers, which form on the side of underwater mountains called seamounts, are among three deep-sea resources that have been proposed to the ISA as a target for mining. In 2020, a two-hour operation funded by the Japanese government excavated a roughly 120-metre-long strip of cobalt-rich crust on a seamount in the northwest Pacific Ocean, as a test run for mining activities.To investigate the operation’s effects, scientists reviewed video footage collected by a remotely operated vehicle. They found that, in the year after the excavation, the density of active swimming animals, such as fish and shrimp, dropped by 43% in areas directly affected by sediment kicked up by mining, and by 56% in adjacent areas.

Animals observed during a study of the effects of deep-sea mining included those in the categories Actiniaria, Holothuroidea, Pentametrocrinidae (top row, left to right), Euplectellidae, Notocanthiformes and Aspidodiadematidae (bottom row, left to right).Credit: JOGMEC

Travis Washburn, a benthic ecologist and co-author of the study who at the time was at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, says that he didn’t expect to see any ecological impacts from such a small mining operation. He suggests that the fish and shrimp swam away from the area because the mining and sediment pollution might have affected their food supply. The results show that effects are felt beyond the mining areas “by a pretty substantial amount”, he says.A study3 published last week suggests that tuna near the ocean surface could gravitate to areas likely to be affected by mining. Writing in npj Ocean Sustainability, scientists project that climate change will drive large numbers of the fish into the Clarion–Clipperton Zone (CCZ), a 4.5-million-square-kilometre area in the eastern Pacific Ocean between Hawaii and Mexico where much of the mining interest is focused. The study predicts that by middle of the century, the zone’s total biomass of skipjack (Katsuwonus pelamis) will rise by around 31% and yellowfin (Thunnus albacares) by 23%.
Tuna catch rates soared after creation of no-fishing zone in Hawaii
Data about deep-sea mining’s effects on animals in the upper layers of the sea are scare. But co-author Diva Amon, a marine biologist and a scientific adviser to the Benioff Ocean Science Laboratory at the University of California, Santa Barbara, says that deep-sea mining could harm tuna and other organisms, such as Pacific leatherback turtles (Dermochelys coriacea).Plumes of sediment stirred up by mining could contaminate sea water and damage fishes’ gills and filter-feeding apparatus, says Amon. The same problems could occur when mining waste is thrown back into the water. Furthermore, noise from the mining operations could alter the tunas’ feeding and reproductive behavior, she adds.“Deep-sea mining will potentially have impacts from the sea surface right down to the sea floor,” says Amon.Is deep-sea mining more damaging than mining for these minerals on land?Proponents of deep-sea mining, such as The Metals Company, a mining start-up based in Vancouver, Canada, that is seeking permission to harvest metals on the sea floor, argue that deep-sea mining will benefit the environment by helping the shift to a green economy. They also argue that sediment plumes’ effects can be minimized and that mining contractors don’t currently propose to release waste from exploiting mineral-rich sea floor deposits called polymetallic nodules.Amon says that deep-sea mining is unlikely to replace terrestrial mining, so comparing one with the other is not helpful. “Both will proceed, and we’ll see double destruction in two different parts of the planet,” she says.Washburn says that deep-sea mining might cause less direct damage to people than does terrestrial mining. But by spoiling huge swathes of the sea floor, it could disrupt marine processes such as carbon sequestration, which helps to offset humans’ greenhouse gas emissions.“I don’t think anybody has enough information to say which one is better or worse,” he says.What are the key questions that still need to be answered?Scientists first need to know more about what lives in the deep ocean, says Amon. Then they can begin to investigate how extensive mining can be before it causes serious harm to key ecosystem functions, such as the ocean’s ability to sequester carbon. The challenge, she says, is that deep-ocean science is slow and expensive, and scientists need more time and money to understand mining’s consequences.
Electric cars and batteries: how will the world produce enough?
Matthew Gianni, co-founder of the Deep-Sea Conservation Coalition, a conservation group based in Amsterdam, says that deep-sea mining could become unnecessary thanks to advances in recycling and the advent of batteries that use iron and phosphate instead of nickel and cobalt. Furthermore, improvements in environmental standards for terrestrial mining will lessen the industry’s ecological damage.Washburn, who started his career studying ecological disasters such as 2010’s Deepwater Horizon oil spill, is buoyed by the efforts to assess potential impacts before the mining operations begin. Historically, humanity tends to act first and consider the consequences later, he says.“We’re actually trying to figure it out beforehand so that’s a pretty good place to be,” he says. More

Phytoplankton bloom off the coast of France in 2004. The greener ocean colour over the past 20 years might be related to increased phytoplankton activity.Credit: NASA/AFP via Getty

More than half of the world’s oceans have become greener in the past 20 years, probably because of global warming. The discovery, reported today in Nature1, is surprising because scientists thought they would need many more years of data before they could spot signs of climate change in the colour of the oceans.“We are affecting the ecosystem in a way that we haven’t seen before,” says lead author B. B. Cael, an ocean and climate scientist at the National Oceanography Centre in Southampton, UK.The ocean can change colour for many reasons, such as when nutrients well up from its depths and feed enormous blooms of phytoplankton, which contain the green pigment chlorophyll. By studying the wavelengths of sunlight reflected off the ocean’s surface, scientists can estimate how much chlorophyll there is and thus how many living organisms such as phytoplankton and algae are present. In theory, biological productivity should change as ocean waters become warmer with climate change.But the amount of chlorophyll in surface waters can vary markedly from year to year, making it hard to differentiate any changes induced by climate change from the big natural swings. Scientists thought it might take up to 40 years of observations to spot any trends2.Another complicating factor is that numerous satellites have measured ocean colour over time, and each did so in a slightly different way, so the data cannot be combined. Cael’s team decided to analyse data from MODIS, a sensor aboard NASA’s Aqua satellite, which was launched in 2002 and is still orbiting Earth, far surpassing its anticipated six-year lifetime. The researchers looked for trends in seven different wavelengths of light from the ocean, rather than sticking with the single wavelength used to track the often-used single measure of chlorophyll. “I’ve thought for a long time that we could do better by looking at the full colour spectrum,” Cael says.With two decades of MODIS data, the scientists were able to see long-term changes in ocean colour. They observed notable shifts in 56% of the world’s ocean surface, mostly in the waters between the latitudes of 40º S and 40º N. These tropical and subtropical waters generally don’t vary much in colour throughout the year, because the regions don’t experience extreme seasons — and so small long-term changes are more apparent there, Cael says.The intensity of the colour change depends on the wavelength of light measured. In general, the waters are becoming greener over time.To see if the shifts could be linked to climate change, the researchers compared the observations to the results of a model3 that simulated how marine ecosystems might respond to increasing levels of greenhouse gases in the atmosphere. The observed changes matched those in the model.Shades of greenNow, the question is what is turning the oceans greener. It’s probably not a direct effect of increasing sea surface temperatures, Cael says, because the areas where colour change was observed do not match up with those where temperatures have generally risen. One possibility is that the shift might have something to do with how nutrients are distributed in the ocean. As surface waters warm, the upper layers of the ocean become more stratified, making it harder for nutrients to rise to the surface. When there are fewer nutrients, smaller phytoplankton are better at surviving than larger ones, and so changes in nutrient levels could lead to changes in the ecosystem that are reflected in changes in the water’s overall colour.But this is just one idea; the researchers can’t yet say exactly why the changes are happening. “The reason we care about the colour is because the colour tells us something about what’s happening in the ecosystem,” Cael says.The discovery ramps up expectations for the next big mission to monitor ocean colour — NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite. Set to launch in January 2024, PACE will measure ocean colour in many more wavelengths than any previous satellite, a capability known as ‘hyperspectral’.“All of this definitely confirms the need for global hyperspectral missions such as PACE,” says Ivona Cetinić, an oceanographer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who works on PACE. The spacecraft “should allow us to understand the ecological implications of the observed trends in ocean ecosystem structure in years to come.” More

Schistosomiasis, one of the most common human parasitic diseases, is a global menace because of its high rates of infection and contribution to poverty. Over the past two decades, global campaigns using antiparasitic medication have been carried out to combat the scourge of the disease. In 2022, the World Health Organization released guidelines1 to further expand the scale of these mass-treatment campaigns, with the goal of eliminating schistosomiasis as a public-health problem by 2030. Although this strategy has yielded clear public-health benefits2, the following key question remains: what solutions can be devised to further combat schistosomiasis and forge a sustainable future? Writing in Nature, Rohr et al.3 identify an innovative and transdisciplinary solution to reduce cases of schistosomiasis.
Competing Interests
N.C.L. reports personal fees from the World Health Organization related to work on public-health guidelines for schistosomiasis. More

RESEARCH BRIEFINGS
12 July 2023

Extensive fieldwork reveals that island plants have similar functions to plants in other regions of the world, but that the island environment, along with biogeographical and evolutionary processes, filters the life-history characteristics and strategies of the plants, rendering the island flora functionally and ecologically distinct from others. More

A survey of 84 coral ecosystems at 25 locations across the Pacific, Atlantic and Indian ocean basins found plastic debris from human activities in almost all of them, both shallow and deep.The study team, led by marine biologist Hudson Pinheiro at the University of São Paulo, Brazil, set out to survey biodiversity on remote reefs, which the researchers expected to be pristine. But during their sampling, they noticed that “these places are not as pristine as we were thinking”, Pinheiro says. It turned out that 77 of the 84 ecosystems contained macroplastics — plastic items measuring 5 centimetres or more across. The researchers found that this type of plastic waste made up 88% of all human-generated rubbish on the reefs1.Much of the debris found in the more remote locations was discarded fishing gear — including nets, hooks and lines. In some places, the team found evidence of “ghost fishing”, in which discarded fishing nets become stuck in the reefs and continue to trap and kill fish.

An old shoe lodged among corals on a reef near the Philippines.Credit: Luiz A. Rocha, California Academy of Sciences

In non-reef marine ecosystems, artificial plastic waste is usually concentrated near the surface and consists mostly of consumer items. But reefs are different — Pinheiro and his colleagues found that deeper reefs contained more macroplastics than shallow ones. There could be several reasons for this: strong waves can carry plastic away from shallow reefs or push it to the depths, for example. And clean-up efforts to remove plastic happen mainly on shallow reefs.

Marine organisms live alongside waste plastic even at a depth of 130 metres.Credit: Luiz A. Rocha, California Academy of Sciences

The deeper reefs are home to abundant fish species, which might explain why fishing nets and gear dominate the litter in these ecosystems, the authors say. As fewer and fewer fish are found in shallower waters, deep-sea fishing is becoming more common, and the amount of refuse could reflect this. “The fishermen are needing to get further away from shore, to fish in deeper reefs because of the pollution and degradation of the shallow reefs,” says Pinheiro.

Fishing lines tangled in a 100-metre-deep reef in the western Pacific.Credit: Luiz A. Rocha, California Academy of Sciences

The plastic waste can damage coral ecosystems in a number of ways. Ropes and nets can get tangled up in coral and cause breakages when fishers try to retrieve them. Plastic debris can also harbour bacteria and other microorganisms that can damage the coral. “Other studies have associated the presence of plastics with coral disease,” says Pinheiro.

A plastic bag drifts around one of Oman’s coral reefs.Credit: Tane Sinclair-Taylor

With negotiations under way for the United Nations global plastics treaty to end plastic pollution, thought needs to be given to how this kind of deep-reef pollution can be eliminated. “We are not talking about going to a supermarket and you change a plastic bag for a paper bag, we’re talking about people that depend on catching their food,” says Pinheiro, who urges negotiators to consider discussing subsidies and other incentives to help fishers to use less plastic, or developing biodegradable materials that could help put an end to contamination of the deepest coral reefs. More

The European Reference Genome Atlas (ERGA) aims to coordinate the production of high-quality genome sequences that represent eukaryotic biodiversity in Europe. As part of the Earth BioGenome Project, it will foster the widespread use of genomic resources for biodiversity protection, restoration and conservation.
Competing Interests
The authors declare no competing interests. More

Powerful vested interests are threatening the adoption of the proposed European Union Nature Restoration Law. The law would require restoration measures to be in place on 20% of Europe’s land and sea area by 2030, and aims to make the continent’s rivers, agriculture, forests and cities more biodiverse and resilient. The European Commission calculates that between 8 (US$9) and 38 will be returned in ecosystem services for every euro invested in restoration.Voting to pass the law takes place this month in the European Parliament. Opponents are influenced by lobbyists in favour of intensive agriculture, fisheries and the forestry industry, who say that the law would cut jobs and undermine food and energy security (see, for example, go.nature.com/3nhboyr; go.nature.com/44bfn8o; go.nature.com/3reitid). The political debate mostly disregards the law’s importance for mitigating and adapting to climate change.Time is short. The scientific community must fend off opposition by publicly debunking misinformation from lobbyists. The EU cannot reconcile a failure to approve the law with its calls for developing countries to stop clearing their pristine lands. More