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Healthy oceans need healthy soundscapes

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Healthy oceans need healthy soundscapes

Rain falls lightly on the ocean’s surface. Marine mammals chirp and squeal as they swim along. The pounding of surf along a distant shoreline heaves and thumps with metronomic regularity. These are the sounds that most of us associate with the marine environment. But the soundtrack of the healthy ocean no longer reflects the acoustic environment of today’s ocean, plagued with human-created noise.

A global team of researchers set out to understand how human-made noise affects wildlife, from invertebrates to whales, in the oceans, and found overwhelming evidence that marine fauna, and their ecosystems, are negatively impacted by noise. This noise disrupts their behavior, physiology, reproduction and, in extreme cases, causes mortality. The researchers call for human-induced noise to be considered a prevalent stressor at the global scale and for policy to be developed to mitigate its effects.

The research, led by Professor Carlos M. Duarte, distinguished professor at King Abdullah University of Science and Technology (KAUST), and published in the journal Science, is eye opening to the global prevalence and intensity of the impacts of ocean noise. Since the Industrial Revolution, humans have made the planet, the oceans in particular, noisier through fishing, shipping, infrastructure development and more, while also silencing the sounds from marine animals that dominated the pristine ocean.

“The landscape of sound — or soundscape — is such a powerful indicator of the health of an environment,” noted Ben Halpern, a coauthor on the study and director of the National Center for Ecological Analysis and Synthesis at UC Santa Barbara. “Like we have done in our cities on land, we have replaced the sounds of nature throughout the ocean with those of humans.”

The deterioration of habitats, such as coral reefs, seagrass meadows and kelp beds with overfishing, coastal development, climate change and other human pressures, have further silenced the characteristic sound that guides the larvae of fish and other animals drifting at sea into finding and settling on their habitats. The call home is no longer audible for many ecosystems and regions.

The Anthropocene marine environment, according to the researchers, is polluted by human-made sound and should be restored along sonic dimensions, and along those more traditional chemical and climatic. Yet, current frameworks to improve ocean health ignore the need to mitigate noise as a pre-requisite for a healthy ocean.

Sound travels far, and quickly, underwater. And marine animals are sensitive to sound, which they use as a prominent sensorial signal guiding all aspects of their behavior and ecology. “This makes the ocean soundscape one of the most important, and perhaps under-appreciated, aspects of the marine environment,” the study states. The authors’ hope is that the evidence presented in the paper will “prompt management actions … to reduce noise levels in the ocean, thereby allowing marine animals to re-establish their use of ocean sound.”

“We all know that no one really wants to live right next to a freeway because of the constant noise,” commented Halpern. “For animals in the ocean, it’s like having a mega-freeway in your backyard.”

The team set out to document the impact of noise on marine animals and on marine ecosystems around the world. They assessed the evidence contained across more than 10,000 papers to consolidate compelling evidence that human-made noise impacts marine life from invertebrates to whales across multiple levels, from behavior to physiology.

“This unprecedented effort, involving a major tour de force, has shown the overwhelming evidence for the prevalence of impacts from human-induced noise on marine animals, to the point that the urgency of taking action can no longer be ignored,” KAUST Ph.D. student Michelle Havlik said. The research involved scientists from Saudi Arabia, Denmark, the U.S. and the U.K., Australia, New Zealand, the Netherlands, Germany, Spain, Norway and Canada.

“The deep, dark ocean is conceived as a distant, remote ecosystem, even by marine scientists,” Duarte said. “However, as I was listening, years ago, to a hydrophone recording acquired off the U.S. West Coast, I was surprised to hear the clear sound of rain falling on the surface as the dominant sound in the deep-sea ocean environment. I then realized how acoustically connected the ocean surface, where most human noise is generated, is to the deep sea; just 1,000 m, less than 1 second apart!”

The takeaway of the review is that “mitigating the impacts of noise from human activities on marine life is key to achieving a healthier ocean.” The KAUST-led study identifies a number of actions that may come at a cost but are relatively easy to implement to improve the ocean soundscape and, in so doing, enable the recovery of marine life and the goal of sustainable use of the ocean. For example, simple technological innovations are already reducing propeller noise from ships, and policy could accelerate their use in the shipping industry and spawn new innovations.

Deploying these mitigation actions is a low hanging fruit as, unlike other forms of human pollution such as emissions of chemical pollutants and greenhouse gases, the effects of noise pollution cease upon reducing the noise, so the benefits are immediate. The study points to the quick response of marine animals to the human lockdown under COVID-19 as evidence for the potential rapid recovery from noise pollution.

Using sounds gathered from around the globe, multimedia artist and study coauthor Jana Winderen created a six-minute audio track that demonstrates both the peaceful calm, and the devastatingly jarring, acoustic aspects of life for marine animals. The research is truly eye opening, or rather ear opening, both in its groundbreaking scale as well as in its immediacy.

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Microscale robot folds into 3D shapes and crawls

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Cornell University researchers have created microscale robots less than 1 millimeter in size that are printed as a 2D hexagonal “metasheet” but, with a jolt of electricity, morph into preprogrammed 3D shapes and crawl.

The robot’s versatility is due to a novel design based on kirigami, a cousin of origami, in which slices in the material enable it to fold, expand and locomote.

The team’s paper, “Electronically Configurable Microscopic Metasheet Robots,” published Sept. 11 in Nature Materials. The paper’s co-lead authors are postdoctoral researchers Qingkun Liu and Wei Wang. The project was led by Itai Cohen, professor of physics. His lab has previously produced microrobotic systems that can actuate their limbs, pump water via artificial cilia and walk autonomously.

In a sense, the origins of the kirigami robot were inspired by “living organisms that can change their shape.” Liu said. “But when people make a robot, once it’s fabricated, it might be able to move some limbs but its overall shape is usually static. So we’ve made a metasheet robot. The ‘meta’ stands for metamaterial, meaning that they’re composed of a lot of building blocks that work together to give the material its mechanical behaviors.”

The robot is a hexagonal tiling composed of approximately 100 silicon dioxide panels that are connected through more than 200 actuating hinges, each about 10 nanometers thin. When electrochemically activated via external wires, the hinges form mountain and valley folds and act to splay open and rotate the panels, allowing the robot to change its coverage area and locally expand and contract by up to 40%. Depending which hinges are activated, the robot can adopt various shapes and potentially wrap itself around other objects, and then unfold itself back into a flat sheet.

Cohen’s team is already thinking of the next phase of metasheet technology. They anticipate combining their flexible mechanical structures with electronic controllers to create ultra-responsive “elastronic” materials with properties that would never be possible in nature. Applications could range from reconfigurable micromachines to miniaturized biomedical devices and materials that can respond to impact at nearly the speed of light, rather than the speed of sound.

“Because the electronics on each individual building block can harvest energy from light, you can design a material to respond in programmed ways to various stimuli. When prodded, such materials, instead of deforming, could ‘run’ away, or push back with greater force than they experienced,” Cohen said. “We think that these active metamaterials — these elastronic materials — could form the basis for a new type of intelligent matter governed by physical principles that transcend what is possible in the natural world.”



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Genes with strong impact on menopause timing also link to cancer risk

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New research has found four genes with some of the largest known effects on the timing of menopause discovered to date, providing new insight into links between menopause timing and cancer risk.

Genes come in pairs, and when women only have one working copy of the four new genes identified (ETAA1, ZNF518A, PNPLA8, PALB2), they have menopause between two and five-and-a-half years earlier than average.

Published in Nature, the large-scale analysis was funded by the Medical Research Council and Wellcome. The team first looked at variation in data from genetic sequencing of 106,973 post-menopausal female participants in the UK Biobank study. Researchers focussed on rare types of genetic changes which cause a loss of the protein, and investigated their effect on the timing of menopause.

The genetic changes studied are all rare in the population, however their influence on menopause is five times greater than the impact of any previously identified common genetic variant. The strongest effect was found from gene variants in ZNF518A, only found in one in 4,000 women. These variants shortened reproductive lifespan more than most previously identified genes.

Discovering the effect of the genes gives scientists a better understanding of the biological mechanisms underpinning menopause, and links to other diseases.

Study co-lead Professor Anna Murray, of the University of Exeter Medical School, said: “For decades, menopause has been under-researched, yet now this is a rapidly evolving area of science. The timing of menopause has a huge impact on women as they plan their careers and lives, and understanding the genetic changes is of particular interest in terms of potential treatments that could prolong reproductive life in future.”

When unrepaired DNA damage occurs in eggs, they can die. The rate at which eggs are lost determines when women experience menopause. The team’s previous work has shown that many genes that influence the timing of menopause are likely to do this by affecting the genetic integrity of eggs. The same factors affect other cells and tissue types in parallel, and in this new study, the team found that many of the genes linked to menopause timing are also risk factors for cancer. These include changes in the BRCA1 and BRCA2 genes, which result in earlier menopause and also in increased risk of cancer.

This is thought to be the process at play in a fifth new gene linked to menopause timing (SAMHD1). The team discovered that changes in this gene can cause women to go through menopause over a year later than average. The researchers also found for the first time that changes in this gene cause predisposition to various cancers in men and women.

Professor John Perry, co-lead from the MRC Epidemiology Unit at the University of Cambridge added: “Past research suggests the female ovary ages at a faster rate than other organ in the body, and this is a model system for understanding the biology of broader ageing. Our latest research builds on this concept, demonstrating that studying ovarian ageing will not only lead to a better understanding of the biology behind infertility and other reproductive disorders, but will enhance our understanding of fundamental processes that regulate DNA damage and cancer risk in the general population.”

Using data from the 100,000 Genomes project, led by Genomics England and NHS England, the team next found that mothers with a high number of genetic variants that cause earlier menopause tended to have more new changes in the DNA they passed onto their children. The study authors believe this is because the relevant genes are involved in repairing damage to DNA, so this function may be compromised in the ovaries, enabling new genetic changes to occur in the eggs.

Dr Hilary Martin, a study co-lead from the Wellcome Sanger Institute, said: “New changes to the DNA in the egg or sperm are the source of all genetic variation in humans, contributing to differences between individuals in their appearance, behaviours and risk of disease. Until now, we knew very little about what influences these new DNA changes, apart from parental age. This is the first time we’ve seen that existing common variation in DNA influences the rate of these changes.”



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Mirror, mirror, in my tank, who’s the biggest fish of all?

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What if that proverbial man in the mirror was a fish? Would it change its ways? According to an Osaka Metropolitan University-led research group, yes, it would.

In what the researchers say in Scientific Reports is the first time for a non-human animal to be demonstrated to possess some mental states (e.g., mental body image, standards, intentions, goals) which are elements of private self-awareness, bluestreak cleaner wrasse (Labroides dimidiatus) checked their body size in a mirror before choosing whether to attack fish that were slightly larger or smaller than themselves.

The team of OMU Graduate School of Science student Taiga Kobayashi, Specially Appointed Professor Masanori Kohda, Professor Satoshi Awata, and Specially Appointed Researcher Shumpei Sogawa, and Professor Redouan Bshary of Switzerland’s University of Neuchâtel, were among the group that last year reported the cleaner wrasse could identify photographs of itself as itself, based on its face through mirror self-recognition.

This time, the cleaner wrasse’s behavior of going to look in the mirror installed in a tank when necessary indicated the possibility that the fish were using the mirror to check their own body size against that of other fish and predict the outcome of fights.

“The results that fish can use the mirror as a tool can help clarify the similarities between human and non-human animal self-awareness and provide important clues to elucidate how self-awareness has evolved,” doctoral candidate Kobayashi declared.

This study was financially supported by JST SPRING (JPMJSP2139 to T.K.), JSPS KAKENHI (23KJ1829 to T.K., 19F19713 and 20K20630 to M.K., 22H02703 to S.A., and 20K20154 to S.S.), Swiss Science Foundation (310030_192673 to R.B.), and an OCU Strategic Research Grant 2018-2019 (to M.K. and S.A.).



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