A team of chemists just solved the mystery of why comets' heads -- but not their tails -- glow green, which had puzzled researchers for decades. From a report: Studying an elusive molecule, which only fleetingly exists on Earth, was the key. Comets are speeding chunks of ice and dust left over from the formation of the solar system, which occasionally venture from the system's cold outer reaches to pass by Earth. Back in the 1930s, Gerhard Herzberg, who later won the Nobel prize for his research on free radicals and other molecules, guessed that the process behind the green comet glow might involve a molecule made from two carbon atoms bonded together, called dicarbon. A new study, published in the journal the Proceedings of the National Academy of Sciences, put Herzberg's theory to the test.

Dicarbon is so reactive that the team behind the study couldn't get their supply of it from a bottle, says Tim Schmidt, a chemist who oversaw the study at the University of New South Wales in Sydney, Australia. In space, it exists inside stars, nebulae, and comets. But when exposed to the oxygen in Earth's atmosphere, dicarbon will quickly react and "burn up," Schmidt says. Schmidt says this is the first time scientists have been able to examine precisely how the molecule breaks apart when exposed to powerful ultraviolet rays. In the lab, the team had to simulate the environment of near-Earth space with vacuum chambers and three different ultraviolet lasers. Because dicarbon reacts so quickly, they had to synthesize it on the spot by whittling away a larger molecule with a laser.

Nasa's Imaging X-ray Polarimetry Explorer (IXPE) has successfully extended its 4-metre boom arm to assume its operational configuration. From a report: Launched on 9 December atop a SpaceX Falcon 9 rocket from the Kennedy Space Centre in Florida, IXPE is a space observatory designed to study X-rays from black holes, neutron stars and other exotic celestial objects. To bring X-rays into focus requires a long telescope because mirrors cannot bend the highly energetic rays by large amounts. Instead they have to be coaxed into focus with a device called a grazing incidence telescope. IXPE has three of these. Each sits on the end of the boom arm and directs light into the instruments in the body of the spacecraft. By measuring the polarisation of the X-rays, IXPE will reveal information about the magnetic environment of their targets. At launch the spacecraft was roughly cubic, about 1-metre long on each side, with the 4-metre-long boom arm folded into a canister 0.3 metres in length. This allowed the IXPE to fit into the nose cone of the rocket. On 15 December, the spacecraft extended the boom. Mission personnel are now working to commission the telescope, ready for science observations to begin in the new year.

An 8-foot-long skull discovered in the Augusta Mountains of Nevada is the largest fossil ever found from its time. The research team believes that the remarkable discovery could provide insight into how modern whales developed, and how to preserve their presence in our oceans. From a report: The fossil -- a newly discovered species of ichthyosaur, a type of large aquatic reptile -- dates to about 246 million years ago. The newly-named cymbospondylus youngorum is, according to the research team, the largest animal found from that time period, both in the sea and on land. It currently holds the title of the first giant animal to ever inhabit Earth. The well-preserved skull was excavated along with part of the creature's backbone, shoulder and forefin. At more than 55 feet long, the ichthyosaur was estimated to be the size of a large sperm whale, according to the study released Thursday by the American Association for the Advancement of Science and the Natural History Museums of Los Angeles County. The ichthyosaur has an elongated snout and conical teeth, leading researchers to believe it ate squid and fish. It also could have hunted smaller marine reptiles and younger members of its species.

It's one of the biggest puzzles in modern astronomy: Based on multiple observations of stars and galaxies, the universe seems to be flying apart faster than our best models of the cosmos predict it should. Evidence of this conundrum has been accumulating for years, causing some researchers to call it a looming crisis in cosmology. Now a group of researchers using the Hubble Space Telescope has compiled a massive new dataset, and they've found a-million-to-one odds that the discrepancy is a statistical fluke. From a report: In other words, it's looking even more likely that there's some fundamental ingredient of the cosmos -- or some unexpected effect of the known ingredients -- that astronomers have yet to pin down. "The universe seems to throw a lot of surprises at us, and that's a good thing, because it helps us learn," says Adam Riess, an astronomer at Johns Hopkins University who led the latest effort to test the anomaly.

The conundrum is known as the Hubble tension, after astronomer Edwin Hubble. In 1929 he observed that the farther a galaxy is from us, the faster it recedes -- an observation that helped pave the way toward our current notion of the universe starting with the big bang and expanding ever since. Researchers have tried to measure the universe's current rate of expansion in two primary ways: by measuring distances to nearby stars, and by mapping a faint glow dating back to the infant universe. These dual approaches provide a way to test our understanding of the universe across more than 13 billion years of cosmic history. The research has also uncovered some key cosmic ingredients, such as "dark energy," the mysterious force thought to be driving the universe's accelerating expansion.

It's conceivable that extraterrestrial intelligences are using powerful lasers to grab our attention, but we lack the proper tools to notice. A newly deployed system might be exactly what's needed for us to finally make contact. From a report: Two laser-detecting devices were recently installed on the summit of Haleakala, also known as East Maui Volcano, according to a University of Hawai'i press release. The devices, mounted on the rooftops of an existing building, will now work in concert with similar devices installed in California, at the Robert Ferguson Observatory in Sonoma. Together, these scanners will scour the Pacific skies in hopes of detecting powerful laser pulses sent by an extraterrestrial civilization. Unlike traditional SETI, which seeks to detect alien radio transmissions, optical SETI looks for signs of artificially created light. It makes sense that advanced aliens would want to use lasers for the purpose of communication, as messages transmitted over light have "a fundamental advantage over radio in that it can, in principle, convey far more bits per second -- typically a half-million times as many," according to the SETI Institute, which runs the LaserSETI program. Aliens could use lasers to communicate across interstellar distances, whether to off-world colonies or fledgling civilizations seeking to make first contact. The newly installed system, a collaboration between the SETI Institute and the University of HawaiÊi Institute for Astronomy (IfA), can now monitor more sky than before.

FFP stands for "filtering face piece." It is a European standard for mask efficiency, ranging from one, the lowest grade, to three, the highest. The Economist adds: FFP2 masks filter at least 94% of all aerosols, including airborne viruses such as covid-19. America's N95 and China's KN95 masks provide similar levels of protection. These disposable masks have several layers of different fabrics, including a polypropylene filter, made by "melt-blowing" polymer to create miniscule, irregular fibre patterns that can trap the smallest airborne particles. A study published in December by the Max Planck Institute, a German research organisation, found well-fitting FFP2 masks reduced the risk of infection with covid-19 to 0.1%. Cloth or medical masks, on the other hand, merely disrupt the airflow of the speaker and trap the largest aerosol particles in their woven material. Their efficacy varies wildly depending on the design and fabric used: tight-fitting, multi-layered masks made from dense materials are much more effective than single-layer linen masks. One study in the Journal of Education and Health Promotion found surgical masks were three times more effective at preventing inhalation of aerosols than homemade cloth ones. Another study, in JAMA Internal Medicine, a journal, compared different cloth masks and found that their efficacy at containing viral particles ranged from 26% to 79%.

Decades of tension, debate, and determination have led to this moment, as the James Webb Space Telescope begins its million-mile journey into deep space. From a report: For the world's most advanced space telescope, and the thousands of people who've worked on it over the decades, the starting gun is about to fire. After more than a quarter-century of planning, designing, building, waiting -- and of obsessively testing the most complex space observatory ever assembled -- the mammoth James Webb Space Telescope is scheduled to launch at 7:20 a.m. eastern time on December 25. Whether that launch represents a year-end gift to science or a catastrophic conclusion to 2021 depends on two things: a safe rocket ride into the sky, and the weeks immediately afterward.

For JWST's mission to succeed, the telescope must execute an intricate series of carefully choreographed maneuvers during its first month in space. Even a single misstep could compromise the entire mission. And the telescope must perform its devilishly difficult dance far beyond the reach of human hands, hurtling toward a point in space a million miles away. "This is a high-risk and a very high-payoff program," NASA deputy administrator Pam Melroy said during a call with reporters on December 21. "There are a lot of hard, long weeks ahead, where the telescope has to deploy perfectly."

But the risk is worth the reward. When JWST opens its golden, 21-foot-wide eye, it will transform our view of the cosmos and of ourselves. The telescope's mission is to tell the story of the universe, from a few beats after its radiant, percussive birth through the sweep of cosmic ages until now -- when humans craft machines that are powerful enough to look back to the beginnings of space and time. With an eye that's sensitive enough to see a bumblebee in lunar orbit, the telescope will peer into the primordial murk from which stars, galaxies, and planets emerged, piercing the darkness that has occluded the gaze of other great observatories.

The Food and Drug Administration authorized a second at-home antiviral pill to treat COVID-19 on Thursday. From a report:The clearance for the drug, called molnupiravir, came a day after the agency signed off on Pfizer's COVID-19 antiviral, called Paxlovid. Both drugs reduce the risk of hospitalization and death in people diagnosed with COVID-19 and at risk of having a severe case of the disease. Molnupiravir, made by pharmaceutical company Merck, is authorized for people 18 years of age and older who are at a high risk of getting seriously ill if they contract the coronavirus. It's a higher age cutoff than Paxlovid, which is cleared for people 12 and up, because molnupiravir might affect bone and cartilage growth, the FDA said in a statement.

The British Psychological Society: Watching lecture videos is now a major part of many students' university experience. Some say they prefer them to live lectures, as they can choose when to study. And, according to a survey of students at the University of California Los Angeles, at least, many students also take advantage of the fact that video playback can be sped up, so cutting the amount of time they spend on lectures. But what impact does sped-up viewing have on learning? The answer, according to a new paper in Applied Cognitive Psychology, is, within some limits, none. In fact, if used strategically, it can actually improve learning. However, what students think is going to be the best strategy isn't actually what's most beneficial, Dillon Murphy at UCLA and colleagues also report. First, the team assigned 231 student participants to watch two YouTube videos (one on real estate appraisals and the other on the Roman Empire) at normal speed, 1.5x speed, 2x speed or 2.5x speed. They were told to watch the videos in full screen mode and not to pause them or take any notes. After each video, the students took comprehension tests, which were repeated a week later. The results were clear: the 1.5x and 2x groups did just as well on the tests as those who'd watched the videos at normal speed, both immediately afterwards and one week on. Only at 2.5x was learning impaired.

When the team surveyed a separate group of UCLA students, they found that a massive 85% usually watched pre-recorded lectures at faster than normal speed. However, 91% said they thought that normal speed or slightly faster (1.5x) would be better for learning than 2x or 2.5x. These new results certainly suggest that this isn't right: double-time viewing was just as good as normal viewing. It seems, then, that as long as the material can still be accurately perceived and comprehended, it's okay to speed up playback. So, a student could just watch videos at 2x speed and halve their time spent on lectures...Or, according to the results of other studies reported in the paper, they could watch a video at 2x normal speed twice, and do better on a test than if they'd watched it once at normal speed. The timing mattered, though: only those who'd watched the 2x video for a second time immediately before a test, rather than right after the first viewing, got this advantage.

Slashdot readers fahrbot-bot and Tangential share a report from Defense One: Within weeks, scientists at the Walter Reed Army Institute of Research expect to announce that they have developed a vaccine that is effective against COVID-19 and all its variants, even Omicron, as well as previous SARS-origin viruses that have killed millions of people worldwide. Walter Reed's Spike Ferritin Nanoparticle COVID-19 vaccine, or SpFN, completed animal trials earlier this year with positive results. Phase 1 of human trials, which tested the vaccine against Omicron and the other variants, wrapped up this month, again with positive results that are undergoing final review, Dr. Kayvon Modjarrad, director of Walter Reed's infectious diseases branch, said in an exclusive interview with Defense One. The new vaccine will still need to undergo phase 2 and phase 3 trials.

Unlike existing vaccines, Walter Reed's SpFN uses a soccer ball-shaped protein with 24 faces for its vaccine, which allows scientists to attach the spikes of multiple coronavirus strains on different faces of the protein. The vaccine's human trials took longer than expected, he said, because the lab needed to test the vaccine on subjects who had neither been vaccinated nor previously infected with COVID. The next step is seeing how the new pan-coronavirus vaccine interacts with people who were previously vaccinated or previously sick. The next step is seeing how the new pan-coronavirus vaccine interacts with people who were previously vaccinated or previously sick. Walter Reed is working with a yet-to-be-named industry partner for that wider rollout.

An anonymous reader quotes a report from the Associated Press: Intel has told workers that unvaccinated people who don't get an exemption for religious or medical reasons will be on unpaid leave beginning in April. The California-based semiconductor company told employees last month they had a Jan. 4 deadline to be vaccinated against COVID-19 or seek an exemption, citing a government mandate for federal contractors.

In a Dec. 7 memo to employees, Chief People Officer Christy Pambianchi told employees the Jan. 4 vaccine deadline remains in place. She wrote that employees who aren't vaccinated must seek a medical or religious accommodation and submit to weekly testing, regardless of whether they are still working remotely. Intel will review employees' exemption requests until March 15. Pambianchi said employees who don't receive an exemption will begin unpaid leave on April 4 for at least three months but "will not be terminated." She said Intel will continue providing health care benefits to unvaccinated employees on leave.

The US Food and Drug Administration on Wednesday authorized Pfizer's antiviral pill, Paxlovid, to treat Covid-19. From a report: This is the first antiviral Covid-19 pill authorized for ill people to take at home, before they get sick enough to be hospitalized. High-risk individuals age 12 and older who weigh at least 88 pounds and have a positive SARS-CoV-2 test are eligible for this treatment and will need to have it prescribed by a doctor. The pill "should be initiated as soon as possible after diagnosis of Covid-19 and within five days of symptom onset," according to an FDA statement. Paxlovid combines a new antiviral drug named nirmatrelvir and an older one called ritonavir and is administered as three pills given twice a day for five days.

From Mount Everest to the Mariana Trench, microplastics are everywhere -- even high in the Earth's troposphere where wind speeds allow them to travel vast distances, a new study has found. From a report: Microplastics are tiny fragments -- measuring less than 5mm -- that come from packaging, clothing, vehicles and other sources and have been detected on land, in water and in the air. Scientists from the French national research institute CNRS sampled air 2,877 metres above sea level at the Pic du Midi Observatory in the French Pyrenees, a so-called "clean station" because of the limited influence exerted on it by the local climate and environment. There they tested 10,000 cubic metres of air a week between June and October of 2017 and found all samples contained microplastics.

Using weather data, they calculated the trajectories of different air masses preceding each sample and discovered sources as far away as north Africa and North America. The study's main author, Steve Allen of Dalhousie University in Canada, told AFP that the particles were able to travel such distances because they were able to reach great altitudes. "Once it hits the troposphere, it's like a superfast highway," he said. The research also points to microplastic sources in the Mediterranean Sea and the Atlantic Ocean.

A rare look inside a fossilized dinosaur egg found in southern China has revealed an exquisitely preserved embryo -- and evidence suggesting that some of these prehistoric creatures had even more in common with modern birds than previously thought. From a report: Scientists said the embryo inside the egg, which was laid between 72 million to 66 million years ago during the Late Cretaceous period, was that of a two-legged, feathered carnivore known as an oviraptorid. They said, in a paper about the discovery published Tuesday in the journal iScience, the embryo's curled body position -- with its back against the blunt end of the 7-inch-long egg and its head between its legs -- resembles that of bird embryos.

"This posture was previously not recognized in any dinosaur embryo," said Fion Waisum Ma, a vertebrate paleontologist at the University of Birmingham in England and a co-author of the paper. She said the posture suggests that the embryo had assumed a tucked position before hatching -- a behavior previously thought unique to birds. She called the newly described specimen "one of the best preserved dinosaur embryos ever found." In birds, tucking leaves the embryo with its right wing over its head and its beak pointing toward an air space at the egg's blunt end. That orientation helps direct the hatchling's head as it uses its beak to crack the eggshell and emerge.

"Failure to attain this posture would increase the chance of death, as the bird is less likely to break out of the egg successfully," Ms. Ma said. An inspection of the oviraptorid egg showed what appeared to be an air space between the embryo's spine and the egg's blunt end, according to the researchers. The specimen was among several fossils discovered about two decades ago in the Chinese city of Ganzhou but not recognized to be fossilized dinosaur eggs until 2015, when evaluated by an expert. A close examination of one of the eggs, which had fossilized after breaking, showed that it held the preserved oviraptorid embryo.

Researchers have developed a rechargeable lithium-ion battery in the form of an ultra-long fiber that could be woven into fabrics. From a report: In a proof of concept, the team behind the new battery technology has produced the world's longest flexible fiber battery, 140 meters long, to demonstrate that the material can be manufactured to arbitrarily long lengths. The work is described today in the journal Materials Today. [...] The new fiber battery is manufactured using novel battery gels and a standard fiber-drawing system that starts with a larger cylinder containing all the components and then heats it to just below its melting point. The material is drawn through a narrow opening to compress all the parts to a fraction of their original diameter, while maintaining all the original arrangement of parts.

While others have attempted to make batteries in fiber form, [says MIT postdoc Tural Khudiyey, a lead author on the paper], those were structured with key materials on the outside of the fiber, whereas this system embeds the lithium and other materials inside the fiber, with a protective outside coating, thus directly making this version stable and waterproof. This is the first demonstration of a sub-kilometer long fiber battery which is both sufficiently long and highly durable to have practical applications, he says. The fact that they were able to make a 140-meter fiber battery shows that "there's no obvious upper limit to the length. We could definitely do a kilometer-scale length," he says.

The 140-meter fiber produced so far has an energy storage capacity of 123 milliamp-hours, which can charge smartwatches or phones, he says. The fiber device is only a few hundred microns in thickness, thinner than any previous attempts to produce batteries in fiber form. In addition to individual one-dimensional fibers, which can be woven to produce two-dimensional fabrics, the material can also be used in 3D printing or custom-shape systems to create solid objects, such as casings that could provide both the structure of a device and its power source. To demonstrate this capability, a toy submarine was wrapped with the battery fiber to provide it with power. Incorporating the power source into the structure of such devices could lower the overall weight and so improve the efficiency and range they can achieve.

An anonymous reader quotes a report from TechCrunch: A security researcher found a Bluetooth vulnerability in a popular at-home COVID-19 test allowing him to modify its results. F-Secure researcher Ken Gannon identified the since-fixed flaw in the Ellume COVID-19 Home Test, a self-administered antigen test that individuals can use to check to see if they have been infected with the virus. Rather than submitting a sample to a testing facility, the sample is tested using a Bluetooth analyzer, which then reports the result to the user and health authorities via Ellume's mobile app. Gannon found, however, that the built-in Bluetooth analydzer could be tricked to allow a user to falsify a certifiable result before the Ellume app processes the data.

To carry out the hack, Gannon used a rooted Android device to analyze the data the test was sending to the app. He then identified two types of Bluetooth traffic that were most likely in charge of telling the mobile app if the user was COVID positive or negative, before writing two scripts that were able to successfully change a negative result into a positive one. Gannon says that when he received an email with his results from Ellume, it incorrectly showed he had tested positive. To complete the proof-of-concept, F-Secure also successfully obtained a certified copy of the faked COVID-19 test results from Azova, a telehealth provider that Ellume partners with for certifying at-home COVID-19 tests for travel or going into work.

While Gannon's writeup only includes changing negative results to positive ones, he says that the process "works both ways." He also said that, before it was patched, "someone with the proper motivation and technical skills could've used these flaws to ensure they, or someone they're working with, gets a negative result every time they're tested." In theory, a fake certification could be submitted to meet U.S. re-entry requirements. In response to F-Secure's findings, Ellume says it has updated its system to detect and prevent the transmission of falsified results.

InfiniteZero writes: Imaginary numbers are necessary to accurately describe reality, two new studies have suggested. Imaginary numbers are what you get when you take the square root of a negative number, and they have long been used in the most important equations of quantum mechanics, the branch of physics that describes the world of the very small. When you add imaginary numbers and real numbers, the two form complex numbers, which enable physicists to write out quantum equations in simple terms. But whether quantum theory needs these mathematical chimeras or just uses them as convenient shortcuts has long been controversial. In fact, even the founders of quantum mechanics themselves thought that the implications of having complex numbers in their equations was disquieting. In a letter to his friend Hendrik Lorentz, physicist Erwin Schrodinger -- the first person to introduce complex numbers into quantum theory, with his quantum wave function -- wrote, "What is unpleasant here, and indeed directly to be objected to, is the use of complex numbers. quantum wave function is surely fundamentally a real function."

Schrodinger did find ways to express his equation with only real numbers alongside an additional set of rules for how to use the equation, and later physicists have done the same with other parts of quantum theory. But in the absence of hard experimental evidence to rule upon the predictions of these "all real" equations, a question has lingered: Are imaginary numbers an optional simplification, or does trying to work without them rob quantum theory of its ability to describe reality? Now, two studies, published Dec. 15 in the journals Nature and Physical Review Letters, have proved Schrodinger wrong. By a relatively simple experiment, they show that if quantum mechanics is correct, imaginary numbers are a necessary part of the mathematics of our universe. "The early founders of quantum mechanics could not find any way to interpret the complex numbers appearing in the theory," lead author Marc-Olivier Renou, a theoretical physicist at the Institute of Photonic Sciences in Spain, told Live Science in an email. "Having them [complex numbers] worked very well, but there is no clear way to identify the complex numbers with an element of reality." To test whether complex numbers were truly vital, the authors of the first study devised a twist on a classic quantum experiment known as the Bell test. The test was first proposed by physicist John Bell in 1964 as a way to prove that quantum entanglement -- the weird connection between two far-apart particles that Albert Einstein objected to as "spooky action at a distance" -- was required by quantum theory.

The Omicron variant of the coronavirus is spreading faster than the Delta variant and is causing infections in people already vaccinated or who have recovered from the COVID-19 disease, the head of the World Health Organization (WHO) said. From a report: WHO chief scientist Soumya Swaminathan added it would be "unwise" to conclude from early evidence that Omicron was a milder variant that previous ones. "... with the numbers going up, all health systems are going to be under strain," Soumya Swaminathan told Geneva-based journalists. The variant is successfully evading some immune responses, she said, meaning that the booster programmes being rolled out in many countries ought to be targeted towards people with weaker immune systems. "There is now consistent evidence that Omicron is spreading significantly faster than the Delta variant," WHO director-general Tedros Adhanom Ghebreyesus told the briefing. "And it is more likely people vaccinated or recovered from COVID-19 could be infected or re-infected," Tedros said.

New York-based firm Pliant Energy Systems is building a marine system reminiscent of the cuttlefish with its rippling underwater motion, a report from The Economist reveals. The company's biomimetic machine, called Velox, is based on the principle that propellers are nowhere near as efficient as the fins of sea creatures that are prevalent in nature. Interesting Engineering reports: Unlike propellers, fins and flippers can extend around a sea creature, meaning more propulsion without the need for a large protruding propeller that could get caught or damaged by hitting the seabed. Fins are also flexible, meaning that if they do come in contact with any other object in the sea, they are less likely to get damaged. In an interview with The Economist, an ex-marine biologist and founder of Pliant Energy Systems, Benjamin Pietro Filardo, explained how he is designing submersible machines that are propelled using flexible fin-like materials. He said Velox will produce approximately three times as much thrust per unit energy as the average propeller of a small boat. The system can travel underwater and even come out onto land, using its fins almost like robotic legs. The video below shows Velox skating on ice and swimming in a pool.

Filardo showed his new design to America's Office of Naval Research, leading them to commission a new iteration, called C-Ray, that will be faster and lighter than Velox. C-Ray also won't be tethered, unlike Velox, which is currently controlled via a cable. Autonomous swarms of the machine could eventually be used for missions such as undersea patrols, mine removal, and deepsea exploration and monitoring. [...] Filardo said the system has great potential for scalability, giving the blue whale as an example of a massive sea mammal that uses fins for propulsion. Impressively, he also revealed that he is also working on a concept that would allow his system to moor itself, and then use the undulations of its fins, thanks to the sea current, to recharge. A lot of testing is still needed, but if Filardo's system delivers on its promise, we might eventually see giant mechanical sea beasts silently gliding through the oceans.

Wildlife officials in Florida are preparing to feed manatees in the wild, an unprecedented response to the animals' mass starvation caused by the loss of seagrasses they normally eat. From a report: So far this year, 1,056 manatees have died in Florida, nearly double the average for the same period of the past five years, according to state data. While the record tally includes those killed by watercraft and other causes, malnourishment is the main reason propelling the increase, researchers say. The state's total manatee population numbered at least 5,733 in 2019, the most recent year in which officials conducted a count. The U.S. Fish and Wildlife Service declared an "unusual mortality event" along Florida's Atlantic coast this year -- a designation indicating a significant die-off that demands an immediate response. The problem can worsen in the winter when the animals congregate in warmer waters that have become devoid of food, researchers say.

"The status of manatees going into this winter is so poor that without this supplemental feeding to help get them through, we're going to have hundreds and hundreds of [them] dying," said Patrick Rose, executive director of the advocacy group Save the Manatee Club. Seagrasses are disappearing because of deteriorating water quality caused by improperly treated sewage, leaking septic tanks and runoff containing fertilizer used for lawns and agriculture, researchers say. It's part of a broader threat to other marine species, they say, and to Florida's economy, which relies heavily on visitors drawn to the state's coastline.