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A new study led by <a href="https://www.cornell.edu/">Cornell University</a> is providing new details about how climate change is reducing oxygen availability in many lakes around the world. The researchers analyzed data on hundreds of <a href="https://www.earth.com/news/how-will-earths-new-lakes-affect-the-carbon-budget/">lakes</a> to investigate how often the concentration of dissolved oxygen has been dropping below critical levels that are needed to support fish and other marine species.



“Lakes with dissolved oxygen losses strongly outnumber those with gains,” said study lead author Stephen Jane, a postdoctoral fellow at the Cornell Atkinson Center for Sustainability. “At large scales, aerobic organisms are losing available habitat as warming of lakes continues. This is particularly the case for organisms that rely on well-oxygenated cool waters deep in lakes to survive warm periods.”



The experts examined about 25 years of data for more than 400 lakes, most of which were temperate climate lakes located in the United States.&nbsp;



The study revealed that the amount of low oxygen water is increasing by 0.9 to 1.7 percent per decade. The researchers also found that the volume of lake water lacking oxygen has increased by more than 50 percent over the past three decades.



Rising temperatures are extending the number of summer weeks that lakes experience thermal stratification. This is when bodies of water divide into distinct layers due to different temperatures.&nbsp;



In July or August, it is typical for a lake surface to be about 70 degrees while the lake bottom is about 40 degrees. The result of stratification is that oxygen from the atmosphere is prevented from replenishing dissolved oxygen in deep waters, explained Jane. This can cause a state of oxygen deprivation called hypoxia, or even a complete lack of oxygen called anoxia.



“Water temperature and density are related,” said Jane. “So it becomes a situation where basically you have oil and vinegar, where strong water temperature differences between layers causes resistance to mixing – which is stratification.”



Stratification changes lead to more time for deoxygenation - the interruption of the natural oxygenation process - for deep-water habitats, said June.&nbsp;



“We show here that as warming is continuing, the amount of time that lakes exhibit stratification is increasing and this leads to increases in the amount of low-oxygen water in lakes,” explained study co-author Professor Kevin Rose of the Rensselaer Polytechnic Institute. “The bad news is that given projected warming rates, we’ll likely see even greater increases in the amount of oxygen-depleted water in lakes in the future.”



The research is published in the journal <a href="http://dx.doi.org/10.1111/gcb.16525">Global Change Biology</a>.



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Lakes are struggling to maintain oxygen as temperatures rise

A new study led by Cornell University is providing new...

<a href="https://www.earth.com/news/belgian-microbiologists-improve-the-flavor-of-beer/">Beer</a> is one of the oldest and most popular alcoholic beverages in the world. While some people love and other hate the distinct, bitter taste of hops used to flavor beer, new research led by the <a href="https://en.unimib.it/">University of Milano-Bicocca</a> has revealed that particularly “hoppy” brews could have unexpected health benefits. The experts discovered that, in laboratory dishes, chemicals extracted from hop flowers can inhibit the clumping of amyloid beta proteins, which are associated with Alzheimer’s disease (AD) – a debilitating neurodegenerative disease, characterized by memory loss and personality changes in older adults.



Part of the difficulty in treating AD is that there is a considerable time lag between the beginning of underlying biochemical processes and the onset of symptoms, often with several years separating them. Thus, since irreversible damage to the nervous system can occur before one even realizes that they might have the disease, preventive strategies and therapeutics which can intervene before symptoms appear are of increasing scientific interest.



One of these strategies involves so-called “nutraceuticals,” or foods which have certain medicinal properties, such as – as the present study argues – the hop flowers used to flavor beers. The scientists created and analyzed extracts of four common varieties of hops using methods similar to those used in the brewing process. Their analyses revealed that these extracts had antioxidant properties and could prevent amyloid beta proteins from clumping in human nerve cells. The most successful extract was from the Tettnang hop, which is found in many types of lagers and lighter ales.



When the researchers separated this extract into fractions, the one containing high levels of polyphenols exhibited the most powerful antibiotic and aggregation-inhibiting activity and promoted processes allowing the body to eliminate misfolded, neurotoxic proteins. By testing the extract in a C. elegans animal model, the scientists found that it protected the worms from AD-related paralysis, although this effect was not extremely pronounced. These findings nevertheless suggest that hop compounds could serve as the basis for the development of nutraceuticals which halt the development of Alzheimer’s disease.



“Our results show that hop is a source of bioactive molecules with synergistic and multitarget activity against the early events underlying AD development. We can therefore think of its use for the preparation of nutraceuticals useful for the prevention of this pathology,” the authors concluded.



The study is published in the journal <a href="https://doi.org/10.1021/acschemneuro.2c00444">ACS Chemical Neuroscience</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Beer could help protect against Alzheimer’s disease

Beer is one of the oldest and most popular alcoholic...

The Arctic is <a href="https://www.earth.com/news/forest-microclimates-impact-bird-species-diversity/">warming</a> faster than any other part of the world, as evidenced by years of research that reveals how climate change signals are amplified in this frozen region. This accelerated warming has resulted in sea ice becoming thinner, which has implications for the exchange of heat between the ocean and the atmosphere, as well as for many other earth processes. However, the exact ways in which the melting sea ice impacts atmosphere–ice–ocean exchanges is a question that has been difficult to answer, given that it is not easy to make field observations in the Arctic.



In this regard, it is important to understand the timings of the sea ice melt and freeze onsets, as well as the lengths of the melt and freeze seasons. These play a key role in the “heat budget” of the atmosphere–ice–ocean system because when sea ice is present, it insulates the ocean against heat loss. However, until now most studies focused on melt and freeze onsets using remote sensing observations of the ice surface. The interface of ocean and ice, lying underneath the sea ice, has rarely been investigated and so the timings of melt and freeze are not known.&nbsp;



A new study, published in the The Cryosphere, the journal of the European Geosciences Union, has now synthesized data from different sources, collected between 2001 and 2018, to determine the timings of sea ice annual freeze–thaw cycles in parts of the Arctic Ocean. The technology used enables the researchers to measure both the surface and the basal melt/freeze onsets, and follow variations over time, in order to understand the changes in the atmosphere–ice–ocean system in a changing Arctic.&nbsp;



The main source of data for this research was the approximately 100 ice mass balance buoys (IMBs) that have been deployed in the Arctic Ocean since 2000. These instruments are equipped with sensors to measure snow accumulation and melting, ice growth and melt, and internal ice temperature. The acoustic sounders on the IMBs measure the distance to the ice surface and ice base with a resolution of ±1 cm, which allows both melt and freeze onsets of the ice surface and ice base to be identified with high reliability. These can also be related to near-surface air temperature.&nbsp;



The data on ice thickness from the IMBs were compared to results calculated from satellite passive microwave data. In addition, the researchers used upward-looking sonars on moorings and, combining all these sources of data, were able to obtain the first ever complete picture of sea ice freeze-thaw cycles in the Arctic. Their findings could improve our understanding of changes in the atmosphere–ice–ocean system and the mass balance of sea ice in a changing Arctic.



The researchers found that the overall average freeze onset of Arctic multiyear ice occurred almost 3 months later at the basal region than at the surface. “Based on synchronous ice and underlying ocean observations, we found the ice basal freeze-up delay relative to the surface, which can be attributed to the regulation of heat capacity of sea ice itself and the oceanic heat release from the ocean mixed layer and subsurface layer,” said study lead author&nbsp;<a href="https://www.researchgate.net/profile/Ling-Lin-31">Long Lin</a>&nbsp;from the&nbsp;<a href="https://www.cnarc.info/members/21-polar-research-institute-of-china">Polar Research Institute of China</a>.



“Thinner ice thickness and thinner snow cover favors earlier basal freeze onset. The ocean plays a cross-seasonal role in regulating the growth or decay of sea ice." According to Lin, although thinner ice generally experiences a longer freezing season, the total ice growth still cannot offset the sea ice loss in summer. “From another point of view, the self-regulation of the Arctic sea ice–ocean system will delay the loss of Arctic sea ice.”



The researchers also found that the most significant differences in timing of melt onsets between surface and bottom occurred in the Beaufort Gyre region, where basal melt onsets occurred more than half a month earlier than at the surface. In addition, both multiyear ice and first-year ice in this region exhibit a trend towards earlier basal melt onset, which can be attributed to the earlier warming of the surface ocean caused by thinning of sea ice thickness and increasing of sea ice mobility.&nbsp;



These results present the first complete picture of Arctic sea ice freeze-thaw cycle, and its coupling with conditions in the atmosphere above, and the ocean below. It also highlights the importance of synchronous comprehensive monitoring of the atmosphere–ice–ocean system, which helps explain the physical nature of the coupling process.



The researchers call for more intensive and collaborative ice mass balance observations of diverse ice types, and simultaneous observations of upper ocean water properties in the future. This, they hope, will vastly improve our ability to fully understand the Arctic ice–ocean system.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Arctic sea ice cycles reveal impacts of climate change

The Arctic is warming faster than any other part of...

Domestic <a href="https://www.earth.com/news/humans-are-responsible-for-the-risks-of-free-roaming-cats/">cats</a> are favorite pets the world over, but details of their origins and early domestication are not well researched. Previous genetic studies have indicated that domestication most likely took place in the region of the Fertile Crescent, some 12,000 years ago. This is the area in the Middle East where humans first transitioned from a hunter-gatherer to a farming lifestyle, and it is proposed that cat domestication went hand-in-hand with the formation of the first human settlements in this region.&nbsp;



Previous studies support the idea that the African wildcat, Felis silvestris lybica, is the ancestor of modern domestic cats (F. s. catus). However, domestic cats from other regions of early agricultural development, including within other Near and Middle Eastern regions, as well as the Indus Valley of Pakistan, have not been examined to determine whether they also contributed to feline domestication. It is also not clear whether cats were subsequently domesticated in other regions of the world, or whether their distribution spread outwards from the Fertile Crescent.&nbsp;



A new study by researchers from universities in the U.S. and elsewhere around the world, has now sought to clarify these questions. The study made use of more than 200 different DNA markers to investigate the genetic diversity of modern cat populations and establish whether current genetic patterns form discrete groups, which would suggest several possible ancestors and different domestication events. In contrast, if the genetic markers indicate a continuum of diversity from a population center, with differences that can be explained by isolation due to distance, this would indicate that the Fertile Crescent was the only site of domestication.&nbsp;



Leslie A. Lyons, a feline geneticist and Gilbreath-McLorn endowed professor of comparative medicine in the <a href="https://www.umsystem.edu/reach/campus/columbia">University of Missouri-Columbia</a> College of Veterinary Medicine, collected and analyzed DNA from cats in and around the Fertile Crescent area, as well as from sites throughout Europe, Asia and Africa.&nbsp;



Samples of cheek tissue, or gonads (from neutered cats), or whole blood, were collected from 1987 random-bred cats (F.s. catus), four African wildcats (F.s. lybica), and 10 putative hybrids of domestic and European wildcats (F.s. silvestris). The researchers did not focus on DNA from special breeds of cats, which have been developed in the past 200 years. Instead they focused on random-bred cats which would have escaped the intensive selective pressures of breed formation.&nbsp;



The DNA from these samples was analysed for the presence of single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs), which are commonly used genetic markers. In some instances the data from other published studies was used, while data from new specimens was added to increase the sample size and geographic locations. In total, random-bred cat samples came from 40 different countries.



“One of the DNA main markers we studied were microsatellites, which mutate very quickly and give us clues about recent cat populations and breed developments over the past few hundred years,” explained Lyons. “Another key DNA marker we examined were single nucleotide polymorphisms, which are single-base changes all throughout the genome that give us clues about their ancient history several thousands of years ago. By studying and comparing both markers, we can start to piece together the evolutionary story of cats.”



The results of the analysis, published in the journal <a href="http://dx.doi.org/10.1038/s41437-022-00568-4">Heredity</a>, strongly support the theory that cats were first domesticated only in the Fertile Crescent, around the time that humans first began to farm and adopted a more sedentary lifestyle. As settlements grew in size, stored grain and discarded waste would have attracted mice, and bold wildcats probably came closer to capitalize on this abundance. One can imagine that people valued the contribution of the cats to controlling vermin, and thus would have encouraged them.



The genetic diversity of cats in countries close to the Fertile Crescent region indicated that they all had the same progenitors but had become distinctly different over time through a process known as ‘isolation by distance.’ In other words, from this single original domestication event, cats were transported along by humans, as they moved to new locations, where they reproduced and accumulated unique genetic changes. This is in contrast to the domestication events of horses and cattle, which occurred multiple times in disparate parts of the world.&nbsp;



“We can actually refer to cats as semi-domesticated, because if we turned them loose into the wild, they would likely still hunt vermin and be able to survive and mate on their own due to their natural behaviors,” said Lyons. “Unlike dogs and other domesticated animals, we haven’t really changed the behaviors of cats that much during the domestication process, so cats once again prove to be a special animal.”



Lyons, who has researched feline genetics for more than 30 years, said studies like this also support her broader research goal of using cats as a biomedical model to study genetic diseases that impact both cats and people, such as polycystic kidney disease, blindness and dwarfism.



“Comparative genetics and precision medicine play key roles in the ‘One Health’ concept, which means anything we can do to study the causes of genetic diseases in cats or how to treat their ailments can be useful for one day treating humans with the same diseases,” said Lyons. “I am building genetic tools, genetic resources that ultimately help improve cat health. When building these tools, it is important to get a representative sample and understand the genetic diversity of cats worldwide so that our genetic toolbox can be useful to help cats all over the globe, not just in one specific region.”



Throughout her career, Lyons has worked with cat breeders and research collaborators to develop comprehensive feline DNA databases that the scientific community can benefit from, including cat genome sequencing from felines all around the world. In a&nbsp;<a href="https://showme.missouri.edu/2021/dark-matter-in-cat-genomes-may-shed-light-on-human-disease/">2021 study</a>, Lyons and colleagues found that the cat’s genomic structure is more similar to humans than nearly any other non-primate mammal.



“Our efforts have helped stop the migration and passing-down of inherited genetic diseases around the world, and one example is polycystic kidney disease, as 38 percent of Persian cats had this disease when we first launched our genetic test for it back in 2004,” said Lyons. “Now that percentage has gone down significantly thanks to our efforts, and our overall goal is to eradicate genetic diseases from cats down the road.”



Currently, the only viable treatment for polycystic kidney disease has unhealthy side effects, including liver failure. Lyons is now working with researchers at the University of California at Santa Barbara to develop a diet-based treatment trial for those suffering from the disease.



“If those trials are successful, we might be able to have humans try it as a more natural, healthier alternative to taking a drug that may cause liver failure or other health issues,” Lyons said. “Our efforts will continue to help, and it feels good to be a part of it.”



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Cats bonded with humans after a single domestication event

Domestic cats are favorite pets the world over, but details...

On Thursday, December 8, 2022, UK stargazers will get the best view of <a href="https://www.earth.com/news/traces-of-an-ancient-ocean-found-on-mars/">Mars</a> on offer this decade, without needing a telescope to observe the fascinating Red Planet. This will happen because, on Thursday morning, the planet will be located in the opposite direction to the sun, relative to Earth, and will thus appear bigger and brighter, since it will be at its closest point to Earth, just about 50 million miles away. Coincidentally, at 4:58 AM GMT, Mars will also disappear behind the full moon, before reappearing at 5:59 AM (an event called “occultation”).



According to Robert Massey, a scientist at the Royal Astronomical Society, stargazers in the UK will easily be able to see Mars under clear skies by looking east. “If you want to see Mars, go out after sunset when it’s dark and look east,”&nbsp;he advised. “It will be really obvious if you’ve got a clear sky – a brilliant red dot.” Outside UK, Mars - and its occultation by the moon - will also be visible in other parts of western Europe, North America, and North Africa.&nbsp;



Moreover, Dr. Massey explained that two major events involving Mars will occur on Thursday: “opposition”&nbsp;– when the Earth passes between the sun and Mars on its orbit – and “occultation” – when the moon is blocking Mars. While opposition occurs about each 26 months, its occurrence together with occultation is a much rarer, and “very unusual” event. On Thursday morning, opposition will occur at 5:35 AM, about halfway through the occultation event.&nbsp;



“In the hours before that occultation takes place the moon will be just to the right of Mars in the sky,”&nbsp;Massey explained.&nbsp;“If you were to stay up later and later it will get closer and closer until it covers it. But the planet is close throughout December and it’ll be obvious through January too.”



Although the Red Planet will be easily visible with the naked eye, people could get a better view of the polar ice caps and dark markings on its surface by using a telescope.&nbsp;



“People want to know when they’ve seen planets and this is a really good chance to go out and look at Mars. This is a place people talking about traveling to, this is a place where all these rovers are driving around the surface.&nbsp;There might once have been life there and there might just still be simple life there today, so if you want to know where that is, this is the time to go out and look for it,” Massey concluded. &nbsp;



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Mars will disappear behind a full moon this week

On Thursday, December 8, 2022, UK stargazers will get the...