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Sixty-six million years ago, an asteroid wiped out the dinosaurs in a fiery global catastrophe. But we know little about how their successors, the mammals, recovered and took over the world. Now, hidden inside ordinary-looking rocks, an astonishing trove of fossils reveals a dramatic new picture of how rat-sized creatures ballooned in size and began to evolve into the vast array of species—from cheetahs to bats to whales to humans—that rule our planet today.

Amazing fossils reveal how mammals took over after an asteroid wiped out the dinosaurs.

Rise of the Mammals

From singing whales and squeaking bats to thumping spiders and clicking dolphins, the world is filled with the exotic sounds of our fellow creatures. What are they saying? While we believe language sets us apart, some animals demonstrate they can learn our language—like Chaser the dog, who recognizes hundreds of words, and Kanzi the bonobo, who appears to have a sophisticated understanding of spoken English. But can we decode their own communications? NOVA Wonders follows researchers around the globe who are deciphering an amazing array of clues that reveal how animals share information critical to their survival. Will we one day be able to write the bat dictionary or decode the hidden sign language of chimps? And what can these findings tell us about the roots of our own language?

Can we crack the code of animal communication?

What Are Animals Saying?

(This program is no longer available for online streaming.) A seven-mile-wide asteroid collided with Earth 66 million years ago, triggering a chain of events that coincide with the end of the dinosaurs. But experts have long debated exactly what happened when the asteroid struck and how the giant beasts met their end. Now, scientists have uncovered compelling new clues about the catastrophe—from New Jersey to the wilds of Patagonia—and an international expedition of scientists has drilled into the impact crater off the coast of Mexico, recovering crucial direct evidence of the searing energy and giant tsunami unleashed by the asteroid. Join NOVA as scientists piece together a chillingly precise unfolding of the Earth’s biggest cataclysm, moment by moment, and discover how our early mammalian ancestors managed to survive and repopulate the Earth. (Premiered December 27, 2017)

Experts drill into the impact crater of an asteroid that created a worldwide cataclysm.

Day the Dinosaurs Died

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How Seaweed May Help Revive Our Oceans

Kelp’s ability to capture carbon from the ocean could help save marine ecosystems.
In some parts of the ocean, like in the Gulf of Mexico, there is so little oxygen in the water that marine life is actually suffocating. Could kelp help, or is it mostly hype?
Hope or Hype? How Seaweed May Help Revive Our OceansPublished August 1, 2022Narrator: Some ocean scientists are raving about kelp.Scott: There&#x27;s a lot to like about kelp, particularly in its ecosystems benefits.Narrator: Because they think this seaweed can potentially help solve major problems in our oceans today, including dead zones, areas of the ocean where oxygen levels have dropped, killing off all kinds of sea life.Francis: Oxygen&#x27;s just declining so low that fish, other invertebrates, they actually suffocate.Narrator: So, why is this happening? In many cases, it starts with nitrogen and phosphorus, often found in fertilizer, the stuff we use for agriculture, or even our lawns or gardens. Rainwater washes it into streams and rivers and it makes its way into the ocean.Francis: If there&#x27;s too much nutrients that run down from watersheds into a bay, for example, it stimulates these phytoplankton blooms.Narrator: Phytoplankton are single-celled algae. And these blooms can grow out of control, sometimes even visible from space, choking off oxygen from the water and blocking sunlight to the plants below. Eventually the phytoplankton die and they sink.Francis: Even though they&#x27;re really small, when they sink, they decompose, and in that decomposition process, bacteria will use up the oxygen that&#x27;s near the sea floor.Narrator: In many cases, this process is what causes the loss of oxygen in the water. And that&#x27;s what happened in the Gulf of Mexico. The Mississippi empties here, bringing high levels of nitrogen and phosphorus into the Gulf. This is where kelp comes in.Scott: So we started creating this little miniature farm here. One of the great attributes of of seaweeds is it&#x27;s a potent way of absorbing all these luxurious nutrients that&#x27;s far too much for the ocean to really fully absorb.Narrator: In addition, it also is great at capturing carbon at rates 50 times higher than trees on land.Scott: Carbon sequestration is one of the key goals for climate change that we need to address. So there&#x27;s a lot of interest in growing seaweeds simply for sucking carbon and nitrogen out of the waters and putting them into a more stable form.Narrator: But to make an impact, you need a lot of kelp sucking up nutrients and it would take a decent amount of space in the ocean to grow it all.Scott: When you look at it on a map in congregate, it would be about as big as Iowa, but spread out all along the shoreline. And I&#x27;d say we&#x27;re still at that level of trying to distinguish between what&#x27;s real and what&#x27;s possible.Scott: So I&#x27;ve marked the perimeter of the farm with farm buoys. You can see ones over there.Narrator: And then you need to harvest it to prevent it from dying and releasing all of the absorbed nitrogen and phosphorus back into the water.Scott: That&#x27;s some good looking kelp!Narrator: And for farmers to want to grow this much kelp, they&#x27;d need a market to sell it, and the market for kelp in the US is still emerging.Scott: It&#x27;s interesting that when we have more complex food systems, we don&#x27;t value traditional foods.Narrator: Seaweed also has an important cultural significance. Some indigenous communities in the US have been harvesting it for centuries, like in Hawaii, where seaweed is known as limu.Scott: Limu traditionally has been used in our practices in the way we live, not just in our eating.Narrator: And the prospect of large scale production raises a red flag for some.Scott: There&#x27;s concerns in the community about mass producing limu. We&#x27;ve had a lot of history where people have come in from outside of Hawaii and they&#x27;ve done these different types of activities but they&#x27;re not really giving back to the communities here. That&#x27;s one of the questions I always think, how is this helping my community?Narrator: And if we grew huge quantities of kelp for carbon capture, what would we do with it all? Some scientists are exploring the possibility of sinking kelp deep down into the ocean, several thousand feet below the surface, potentially sequestering the carbon for millions of years but there are still a lot of unknowns.Scott: What does happen to that carbon and the seaweed when it goes to 1,000 meters deep? It&#x27;s not like it&#x27;s a complete desert down there. There are still organisms growing. Is that a free lunch for somebody? Are we gonna have a great bloom of something else and some unintended consequences? We need to precede doing those grand ideas with experiments to see what the impact might be.

Kelp’s ability to capture carbon from the ocean could help save marine ecosystems.

Ocean Invaders

Meet one of the ocean’s most beautiful and destructive species: Lionfish.
Lionfish – long prized in home aquariums – have invaded the Atlantic, and are now one of the ocean’s most successful invasive species, wreaking havoc in waters across the globe. Join ocean explorer Danni Washington on a journey to find out how they took over, why they’re doing so much damage, and what can be done about it. These fascinating creatures are a window into the impacts of invasive species in a globalized world where human activity is an increasingly powerful evolutionary force. (Premiering Wednesday, October 26 at 9 pm on PBS)

Meet one of the ocean’s most beautiful and destructive species: Lionfish.

A dried, twisted old tree against a blue sky

"Methuselah," a bristlecone pine in California long considered to be the world's oldest tree. Image Credit: Yen Chao, Flickr

The world’s oldest tree has competition

High on a ridge in California’s Eastern Sierra, a gnarled bristlecone pine known as Methuselah has reigned over almost five millennia’s worth of snowy winters and blazing summers. Methuselah, whose crooked and weather-beaten boughs make it look more like a sculpture than a living thing, is estimated to be 4,853 years old, based on data from a core sample taken in 1957—making it the oldest tree in the world.
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Until now. This year, an upstart competitor has appeared to challenge California’s grizzly old-timer. Nicknamed Alerce Milenario, or Gran Abuelo, which means great grandfather in Spanish, it sits in a humid valley outside La Unión, Chile. As <a href="https://www.science.org/content/article/world-s-oldest-tree-growing-ravine-chile">reported in Science</a> in May, researcher Jonathan Barichivich says new data suggest the tree might hold a new record: 5,484 years old. (That record excludes clonal trees that share root systems, like aspen colonies, Science specified. In the search for the oldest tree, scientists focus on individuals with just one trunk.)Gran Abuelo is an alerce, or Patagonian cypress, a type of conifer related to giant sequoias and coast redwoods. Like their Californian cousins, alerces can grow to very old age; at least one other alerce in southern Chile has been dated at 3,600 years old. That makes the species the second longest-lived in the world—older than sequoias but not quite at the bristlecone pine level. And Barichivich knows alerces well. He grew up around them, including Gran Abuelo, since his grandfather and mother both worked as rangers in the park where Gran Abuelo grows. He says his grandfather discovered the tree around 1972. “It’s a tree that’s very, very close to our hearts,” he told Science.Standard practice in dendrochronology, the science of determining tree age, involves <a href="https://www.pbs.org/wgbh/nova/video/trees-climate-records/">counting rings</a> from a thin core taken from the living tree, then comparing those rings to patterns in cores from trees nearby. But Barichivich ran into a problem: Gran Abuelo’s trunk was so wide that his increment borer, the instrument usually used to take age cores, could not reach all the way through. And while in similar cases some dendrochronologists might take samples from the roots to supplement or confirm available data, Barichivich was concerned that that might damage the tree's roots, which have already struggled under the footsteps of curious tourists coming to see their arboreal elder. "It's not the point to make a big hole in the tree just to know that it's the oldest,” he <a href="https://www.livescience.com/possible-oldest-tree-found-chile">told Live Science</a>. “The scientific challenge is to estimate the age without being too invasive to the tree."Intead, Barichivich used statistical modeling to estimate Gran Abuelo’s age, drawing on data from fully cored alerces nearby and incorporating possible growth rate variation and fluctuations caused by climate and environment. The result that the model suggested shocked him. The absolute oldest the tree might be was 6,000 years, it said. There was an 80% chance that the tree was over 5,000 years old, with an overall estimated age of 5,484. “It was astonishing,” he told Science.
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Though Science reported on Barichivich’s findings in May, he has yet to publish them fully in a peer-reviewed journal. His fellow dendrochronologists have therefore greeted his claims with a mix of intrigue and doubt. “I fully trust the analysis that Jonathan has made,” Swiss Federal Institute of Technology dendrochronologist Harald Bugmann told Science. “It sounds like a very smart approach.”But others remain skeptical. “The ONLY way to truly determine the age of a tree is by dendrochronologically counting the rings, and that requires ALL rings being present or accounted for,” Ed Cook, a founding director of Columbia University’s Tree Ring Laboratory, told the publication via email. Similarly, Peter Brown, who has produced a database of the oldest trees on Earth and serves as Guinness World Records’ consultant on the oldest tree, told <a href="https://www.sfchronicle.com/california/article/California-thinks-its-bristlecone-pine-17201279.php">The San Francisco Chronicle</a> that the project is “awfully interesting,” but he wants to see the details before coming to any conclusions. Plus, <a href="https://www.nationalgeographic.com/environment/article/whats-the-oldest-tree-on-earth-and-will-it-survive-climate-change">he pointed out to National Geographic</a>, Gran Abuelo’s estimated age is over 1,500 years older than the next oldest alerce, which is a pretty big jump. (Barichivich stands by his estimate, citing the “growth-lifespan tradeoff” to Live Science, a theory that posits that slow-growing species tend to live longer—and alerces grow slower than both sequoias and bristlecone pines.)Ultimately, Barichivich emphasizes that “the objective is to protect the tree, not to make headlines or break records.” He <a href="https://www.newsweek.com/conservation-tree-chile-oldest-rare-record-broken-protection-alerce-national-park-1709970%E2%80%9D">told Newsweek</a> he was going public with his research out of concern for Gran Abuelo’s wellbeing, estimating that only 28% of the tree is still alive. (Trees possess a remarkable ability to <a href="https://www.bartlett.com/resources/compartmentalization-of-decay-in-trees.pdf">compartmentalize decay</a>, walling off areas that have been invaded by fungi and microorganisms and prioritizing growth in other areas.) Not only do tourists come too close for comfort, he said, but the tree is currently encircled by a platform that is crushing the remaining living roots. He and his colleagues would like to see the park where the tree lives erect a protective net and move the walkway further from those roots. "To me, this tree is like a family member,” he said. “Seeing him like this is breaking my heart.”Meanwhile in California, the guardians of Methuselah <a href="https://www.sfchronicle.com/california/article/California-thinks-its-bristlecone-pine-17201279.php">told The San Francisco Chronicle</a> that they’re “not concerned” about the southern challenger but are intrigued by Barichivich’s innovations. “Perhaps there are other older trees out there waiting to be discovered with this new potential dating method,” ranger Andrew Kennedy said. That may include in Methuselah’s own backyard. In 1959, a tree ring researcher from University of Arizona collected cores from several of Methuselah’s ancient neighbors, suspecting some might be even older—but died before he could complete his analysis, The Chronicle reports. Then in 2010, another researcher restarted the project, finding one core that seemed to suggest a still-living tree might be 5,062 years old. But that researcher died before the work was complete as well—and then the cores were lost.Meanwhile, these most ancient of trees, having witnessed countless births and deaths and virtually all of modern human history, live on.
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Will a Patagonian cypress in Chile prove older than California’s most elderly bristlecone pine?

Looking down into a pan with a pile of beige mushroom slices

Crimini mushrooms ready to be cooked. Image Credit: joyosity, Flickr

Why you can’t really overcook mushrooms

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You don’t have to be a chef to notice that some foods are more forgiving of kitchen mistakes than others. When you’re cooking vegetables (zucchini, let’s say), if you step out to take a call you might end up with too-soft glop. When you’re cooking meat, if you get distracted you could end up with a hockey puck. But mushrooms are much more forgiving. Even if an unexpected visitor calls you away from a pan of sautéing porcini for an hour, when you come back the mushrooms are likely to still be glossy and tender.A few years ago, Dan Souza at Cook’s Science, run by America’s Test Kitchen, set out to confirm this phenomenon <a href="https://www.youtube.com/watch?v=h0fHS8-l_NU">with an experiment</a>. Souza spent 40 minutes steaming half-inch-thick planks of portobello mushroom, zucchini, and beef tenderloin. Every five minutes, he tested each sample with a fancy machine called a “CT3 Texture Analyzer,” which measured how much force would be required to “bite” three millimeters into each one. He also gave them to human tasters to try. Then he recorded the results.After five minutes of steaming, the zucchini, beef, and mushroom were all equally tender, requiring about the same force for a “bite.” The mushrooms stayed the same for almost the whole 40 minutes, getting only 57% tougher in total—and still seemed tender to the tasters. In deep contrast, the beef was a whopping 293% more leathery after the same period of cooking. Meanwhile, the zucchini decreased 83% in firmness, turning into vegetable mush. So, what gives?
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The answer, it turns out, is chitin, a fibrous polysaccharide—or cluster of chains of carbohydrate molecules—similar to keratin. It’s found in lobster and shrimp shells, <a href="https://www.pbs.org/wgbh/nova/video/edible-insects/">insect wings</a>, and the cells of fungi. It mostly serves to protect soft tissue in the natural world. (It’s also a great source of dietary fiber.)And chitin is remarkably resistant to heat. In 2015, three Japanese researchers <a href="https://www.nature.com/articles/srep11907">published a study</a> exploring the material’s limits, which found that fungal cells with chitinous walls could withstand temperatures up to 380 C (716 F). In contrast, cellulose samples began to warp and eventually dissolved around 300 C. The authors attributed this remarkable strength to chitin’s structure. In mushrooms, chitin takes the form of fine bundles, each of which is made up of sheets that are layered in parallel but run in opposite directions. In α-chitin, the form most common in crustaceans, insects, and mushrooms, those sheets are held together by strong hydrogen bonds, making them even more durable.All that is quite different from the molecular makeup of meat and vegetables. When the strands of the protein in meat are raw, they’re soft and flexible. But as they heat up, they contract together, pushing out moisture. The empty space causes the proteins to contract even further, eventually drying the meat out and turning it hard and tough. In vegetables, on the other hand, the hemicellulose and pectin (another polysaccharide) that hold plant cell walls together begin to break down after exposure to heat, releasing the bond between those cells. And, as the Japanese researchers found, they do so at much lower temperatures than chitin does. 
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Mushrooms are remarkably forgiving. Here’s the science of why.

6 stinking cool facts about dog noses

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Did you know that dogs can use their cold, wet (and cute!) noses to sense sources of heat and thermal radiation? That discovery, via a <a href="https://www.science.org/content/article/new-sense-discovered-dog-noses-ability-detect-heat">2020 study from Sweden</a> that challenged dogs to choose between a warm and cool object across a room, makes them only the second mammal known to possess that superpower. (The other is a vampire bat.)And that’s not all dogs' noses can do. Read on for six reasons why dog noses are among nature’s most amazingly engineered instruments—instruments whose power humans are <a href="https://www.pbs.org/wgbh/nova/video/electronic-nose-imitate-dog-nose/">now trying to recreate</a>: 1. Dogs' <a href="https://www.pbs.org/wgbh/nova/article/dogs-sense-of-smell/">sense of smell</a> is between 10,000 and 100,000 times as potent as humans’. This power comes in part from the up to 300 million olfactory receptors dogs carry around in their noses, compared to our mere 6 million. And the part of the canine brain that is dedicated to smells is 40 times larger than ours, proportionally speaking. 2. Dogs can smell continuously, even while they’re breathing in and out. In contrast, when a human smells a scent (sniffs a rose, for example) we inhale that odor and breathe in oxygen through the same passage. But if a dog smells the same flower, air “splits into two different flow paths, one for olfaction and one for respiration," Brent Craven, a Pennsylvania State University bioengineer who has modeled <a href="https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.20592">canine olfaction anatomy</a> using high-resolution MRIs, <a href="https://www.pbs.org/wgbh/nova/article/dogs-sense-of-smell/">told NOVA</a>.Craven and his colleagues found that a portion of the air dogs inhale gets ushered into a specialized area at the back of the canine nose reserved for odor detection, while the rest of it continues rushing toward the lungs. And when dogs exhale, that air departs through nose slits in a unique aerodynamic pattern that also guides new air in, creating a cycle of breath that continuously supplies the in-house laboratory in the back of the canine nose with new material. In <a href="https://pubmed.ncbi.nlm.nih.gov/8735662/">one study from the University of Oslo</a>, a dog on a hunt sniffed continuously for a full 40 seconds, across 30 respiratory cycles!<h4>Watch: This Device Smells Diseases by Imitating a Dog's Nose</h4>
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3. Dogs can <a href="https://vcahospitals.com/know-your-pet/how-dogs-use-smell-to-perceive-the-world">wiggle their nostrils independently</a>, which helps them figure out which direction a scent is coming from. Humans can only wiggle their nostrils simultaneously. (Try it. We’ll wait.)4. Dogs are great at interpreting all the information coming in through their noses in fine detail. In her book “Inside of a Dog,” canine cognition researcher Alexandra Horowitz writes that humans might taste a teaspoon of sugar added to a cup of coffee. But a dog could detect the same teaspoon of sugar in a million gallons of water—enough to fill two Olympic-sized pools.And to take the sugar metaphor further, “if we humans walk into a bakery, we can say, ‘someone’s baking a pie in here,’” canine search specialist Lynne Engelbert <a href="https://www.pbs.org/wgbh/nova/article/cremation-ashes-sniffing-dogs-california-wildfire/">told NOVA</a>. “A dog would walk in and say, ‘Oh, someone’s baking a pie in here, and it has apples, and butter, and cinnamon, and nutmeg.”
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5. Dogs can connect a human with the scent they leave behind with exceptional precision—and even help diagnose sick humans with a variety of diseases. Forensic chemist Ken Furton, who has studied dog olfaction for more than 25 years, once blew up a car with colleagues and then asked detection dogs to pick out human scent from the resulting debris. The dogs were able to sniff the small amount of shrapnel and correctly identify the people who had been in contact with the bomb pre-explosion 82% of the time.More recently, Furton and his colleagues looked at whether dogs might be trained to identify COVID-19 patients—and found they could do so with 97.5% accuracy. “I was shocked,” he told NOVA. And <a href="https://faseb.onlinelibrary.wiley.com/doi/abs/10.1096/fasebj.2019.33.1_supplement.635.10">one 2019 study</a> indicated humans’ best friends can sniff out cancer with a similarly high 97% accuracy rate.<h4>Watch: Cannabis-Sniffing K-9's: Out of a Job?</h4>
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 6. Dogs can not only identify human remains–they can sniff out already cremated remains from among other ashes. Dogs in the American West are now being trained to <a href="https://www.pbs.org/wgbh/nova/article/cremation-ashes-sniffing-dogs-california-wildfire/">look for the cremated remains</a> of homeowners’ loved ones when those homes are lost to the region's increasingly fierce wildfires. The non-profit Alta Heritage Foundation brings specially trained search dogs and archaeologists to the site of a house destroyed by fire, using canine colleagues to narrow down where the lost ashes might be buried and then archeological techniques to excavate them. The ashes are often the only thing his clients want to recover from their houses, Alta Heritage founder Alex DeGeorgey told NOVA. So being able to find their loved ones’ ashes within the ashes of a house is both powerful and continually surprising. “I’ve done this hundreds of times,” DeGeorgey says of cremation ash recovery, “and I still marvel that we’re able to do it.”
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Dogs can sniff out disease and analyze new odors even as they exhale. But how?

Legal Hemp vs. Illegal Cannabis

To qualify by law in Nebraska as hemp, a cannabis plant must contain less than 0.3% THC, the main psychoactive substance in cannabis. Exceeding 0.3% THC in hemp can result in the destruction of an entire harvest in Nebraska and other states with similar laws. See what farmers and producers of hemp products in Nebraska need to do in order to not cross the line from legal hemp to illegal cannabis.
To qualify by law in Nebraska as hemp, a cannabis plant must contain less than 0.3% THC, the main psychoactive substance in cannabis. This level is low enough to not cause intoxication. Exceeding 0.3% THC in hemp can result in the destruction of an entire harvest in Nebraska and other states with similar laws.THC is just one of many cannabinoids, the compounds in cannabis that interact with specialized receptors in our brains and bodies, which the plants naturally create. THC content can rise or fall at any stage of breeding, growing or processing and can get to concentrations up to 30%—100 times the amount to be classified as hemp.Sweetwater Hemp, in Pleasanton, Nebraska, began processing hemp in 2020. The company purchases the plant and extracts cannabidiol or CBD, another of the many cannabinoids found in cannabis. Unlike THC, the psychoactive CBD does not produce a high. Two weeks before Sweetwater’s anticipated harvest, state regulators are called to take random samples of the crop, which are sent to an independent lab. (Nebraska-based Kennebec Analytical Services is one of the first in the state to get the needed certifications to test cannabis.) The final report provides measurements of multiple cannabinoids and, most importantly, determines whether the THC falls within the 0.3% legal limit to classify the product as hemp. If there is too much THC, the law demands every single plant in the batch be destroyed.The next step is turning the acquired plants into product. Even if the crop hits the legal THC mark, the same rules apply to what’s extracted from the hemp. The part of the cannabis plant with CBD gets hand-stripped from the rest of the plant, soaked in ice water and filtered. After being filtered three times, the mixture comes out as bubble hash and is blended with a concentrated version of coconut oil, which becomes the base ingredient of CBD-based products on the market. Some industry players and consumers think cannabis compounds, like THC, help boost the medicinal qualities of CBD, which is why the producers try to get as close to the legal limit as possible. But more data is needed on the how much THC helps with the medicinal qualities of cannabis, scientists say.This video was produced in collaboration with NOVA and is made possible in part by the Corporation for Public Broadcasting, a private corporation funded by the American people.
Legal Hemp vs. Illegal CannabisPublished: March 31, 2022NARRATOR: These plants are cannabis and they might be illegal in Nebraska, or they might be legal. This cannabis is classified as hemp, and it&#x27;s legal here. By law to qualify as hemp, a plant must contain less than 0.3% THC, the main psychoactive substance in cannabis, a level so low, it&#x27;s not known to be intoxicating. That means in states like Nebraska, exceeding the narrow threshold for THC in hemp can result in a loss of an entire harvest.AMANADA McKINNEY (Medical Doctor, Doane University Faculty, A&amp;A Apothecary Partner): We have to find some way to prevent entire crops from being destroyed, if they&#x27;re just above that, that, that illegal limit, right? That 0.3%.NARRATOR: THC content can rise or fall at any stage of breeding, growing or processing.ANDREA HOLMES (Organic Chemist, Doane University Faculty, A&amp;A Apothecary Owner): Hemp is kind of like a little baby. You don&#x27;t, they don&#x27;t, it doesn&#x27;t always do what you want it to do. So sometimes depending on temperature and climate conditions, the controlling the cannabinoid levels can be difficult. So it&#x27;s, it&#x27;s not easy.NARRATOR: Cannabinoids are the compounds in cannabis that interact with specialized receptors in our brains and bodies. THC is just one of the ingredients that the plant can produce, sometimes up to levels of about 25 to 30%.RORY CRUISE (Sweetwater Hemp CEO): And we&#x27;re down here trying to deal with 0.3% THC. So there&#x27;s a huge difference.NARRATOR: Sweetwater Hemp began processing hemp in 2020. The company purchases the plant and extracts cannabidiol or CBD another cannabinoid from the plant. But unlike THC, it does not produce a high. They&#x27;ve cultivated a couple of research crops in their greenhouses. Growers use genetics to engineer plants that repress their own THC content.RORY CRUISE: They keep being able to find that genetic, create that, that cannabinoid and have that type of plant that creates that specific cannabinoid.NARRATOR: Where the hemp is planted may cause drastic swings in the THC level. Sweetwater recognized its research crop in one of its greenhouses produced high quality plants that push the boundaries on THC content.RORY CRUISE: Those plants, they have the best of both worlds of not dealing with high extremes outside of wind and conditions and, and and those kinds of things. And they just really push and thrive really fast.NARRATOR: Two weeks before Sweetwater&#x27;s anticipated harvest, state regulators are called to take random samples of the crop. The plants are sent to an independent lab. Nebraska-based Kennebec is one of the first in the state to get the needed certifications.CONCETTA DiRUSSO (Kennebec Analytical CEO, University of Nebraska- Lincoln Biochemistry Faculty): We take the sample, we grind it. We sieve it to get the seeds and the stems out. We grind it again to make a very, very fine powder. And then using organic solvents, we extract the cannabinoids.NARRATOR: The final report provides measurements of a whole range of cannabinoids. And most importantly determines whether the THC falls within the 0.3% legal limit.CONCETTA DiRUSSO: I think it&#x27;s, what&#x27;s, what&#x27;s challenging for us, and we keep it always at the forefront, is how important and serious this measurement is. That it means the difference between harvesting and marketing a field of hemp, a greenhouse of hemp, or destroying your crops.NARRATOR: If there is too much THC, the law demands every single plant in the batch be destroyed.Those black buckets are all that remains of a recent Sweetwater hemp crop that tested over 0.3.RORY CRUISE: I was 0.39 on my very first one and 10 days before that I was 0.26.NARRATOR: The team considers it to be part of the learning curve.BRETT MAYO (Sweetwater Hemp Chief Marketing/Extraction Officer): The first time you grew corn, was it perfect? No. The first time you grow soybeans, was it perfect? No.NARRATOR: Next step, turning the acquired plants into product. Even if the crop hits that legal THC mark, the same rules apply to what&#x27;s extracted from the hemp. The flower gets hand stripped off the buds, which are soaked in ice water and filtered.BRETT MAYO: And it then goes through 1, 2, 3, 3 filters before it comes out as bubble hash.NARRATOR: The bubble hash is blended with a concentrated version of coconut oil, which becomes the base ingredients for the dozens of CBD-based products on the market.BRETT MAYO: And the hard part about that is you want to be as close to that 0.3 as possible because THC kind of has a bad reputation. But THC is going to help that product to be better.NARRATOR: Some industry players and consumers think cannabis compounds like THC help boost the medicinal qualities of CBD, but scientists say we need more data.There&#x27;s one other way hemp growers could stay out of trouble; change the federal law and increase the amount of THC allowed.AMANADA McKINNEY: And I think raising the threshold on that would help, especially Nebraska farmers, with growing industrial hemp. So they don&#x27;t have to be so diligent about catching that plant before it&#x27;s gone over that limit.NARRATOR: Whether the law changes or not, those processing and marketing hemp see the crop has its own distinct place in the market. Even in places where cannabis with higher levels of THC remains illegal.CONCETTA DiRUSSO: Oh, it&#x27;s amazing. And I really look forward to how it&#x27;s going to change. I think that these plants have so much to offer in terms of medicinal properties and other things. There&#x27;s a lot of good that comes out of this plant.

To qualify by law in Nebraska as hemp, a cannabis plant must contain less than 0.3% THC, the main psychoactive substance in cannabis. Exceeding 0.3% THC in hemp can result in the destruction of an entire harvest in Nebraska and other states with similar laws. See what farmers and producers of hemp products in Nebraska need to do in order to not cross the line from legal hemp to illegal cannabis.

Animal Care Supervisor Lisa Dijenno bottle-feeds a manatee named Tober. Image courtesy of ZooTampa

A day at a Florida manatee hospital

On December 7, 2021, NOVA Digital Editor Alissa Greenberg visited ZooTampa’s David A. Straz, Jr. Manatee Critical Care Center to see up close how rescued manatees are recovering and regaining strength amid an ecological crisis and widespread starvation.10:15 a.m. It’s feeding time at the manatee critical care center at ZooTampa, and the calves are ready and waiting. Even before the staff brings bottles of thick formula over to the pool where they are swimming, four sets of fuzzy nostrils break the surface, whiskers wiggling. “As you can see, they know it’s time,” says Animal Care Associate Kelcey Innes. The calves, which are all smaller than a duffel bag but may someday weigh close to 1,000 pounds, suck down the formula, then chew on the bottles’ rubber nipples playfully. 
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There will be more food soon enough—calves at the center are fed every four hours around the clock. But for now, Innes and coworker Sabrina Sauseda have a different task: watch for manatee farts, proof of digestive systems in working order. After a few minutes, Sauseda spots telltale bubbles. “Calliope had gas!” she announces.The center keeps up this intensive feeding schedule because if the calves were still nursing with their mothers, they would be gaining at least a pound a day. But these calves are orphans, part of an ongoing manatee crisis in Florida. Manatees are in trouble all over the state—particularly on its Atlantic (east) coast, they are starving. Last year was the <a href="https://www.tampabay.com/news/environment/2022/01/10/a-record-1101-florida-manatees-died-in-2021-when-will-it-end/">deadliest on record</a>, with more than 1,100 manatees dead, close to 15% of the state’s population. The reason is seagrass: The Florida coast is home to what were once two of the largest undersea meadows in North America, and the plant makes up much of the manatee diet. But <a href="https://news.mongabay.com/2021/09/manatee-deaths-in-florida-point-to-a-global-decline-in-seagrass-ecosystems/">Florida's seagrass</a> ecosystems are collapsing, due largely to fertilizer and development runoff. In the Indian River Lagoon, once one of the continent's most productive estuaries, seagrass has declined an estimated 95% in the last 10 years.As one of four manatee critical care centers in the country, ZooTampa is caring for 23 <a href="https://www.mmc.gov/priority-topics/species-of-concern/florida-manatee/">manatees</a> on this December morning, double its historic capacity. A mother manatee may feed her calf until she starves, so the facility has also taken on an unprecedented number of calves in the past year, left alone after their parents perished. As their state attempts to clean up its waterways, the staff at ZooTampa are working overtime to save the animals that mean so much to the soul of Florida.
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<img alt="A woman bottle feeding two manatee calves in a pool" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Animal_Care_Professional_Sabrina_Sauseda_bottl.width-990_eTRwlCm.jpg"/>
<figcaption>Animal Care Professional Sabrina Sauseda bottle-feeds orphaned mantee calves at ZooTampa. Image courtesy of ZooTampa
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10:35 a.m. It’s also time for morning tube feeding. Two new residents have arrived within the last week, along with the early winter chill. Both were suffering from cold stress; one had a fresh boat propeller injury across his face. And they both need to eat while they convalesce.When a new manatee comes to the center after rescue by the Department of Fish and Wildlife, Animal Care Supervisor Jaime Vaccaro and her staff check its blood levels, respiration, and measurements. Then they set the new resident up in one of three medical pools that make up the hospital’s intensive care area. Each of these interconnected pools is equipped with its own heater, a vertical gate that can be lowered to cut off access, and a hydraulic floor that can be raised and lowered. This feature allows the staff to both customize the environment and raise the manatees out of the water for medical care.Last week’s adult arrival, Corduroy, is in too much distress to eat. After they use the hydraulics to lift him out of the pool, Vaccaro and Innes take some of Corduroy’s blood, then gingerly thread a length of plastic tubing down his throat. His tail flaps a little, but he calms and accepts the liquid quietly. Manatees’ complicated digestive systems are especially sensitive, so the staff tube-feed Corduroy multiple times a day to make sure he stays hydrated and maintains his weight until he’s ready to eat on his own—a process that could take months. Manatee digestion is “like the engine of a car,” Vaccaro says. “If they've been sitting for a while, they might not start back up right away.” Director of Conservation, Research, and Behavior Tiffany Burns connects the increasing number of manatee patients with Florida’s persistent water quality problems. “They look big and full of blubber, but they’re very muscular,” she says. “A lot of that body is intestines.” Without much insulation, manatees are very sensitive to temperature. If they swim in too-cold water long enough (anything under 68 F) they develop cold stress, which manifests outwardly in a frostbite-like icing of white, peeling tissue visible on the flippers and muzzles of many of the animals here. And if they stay even longer, they may develop pneumonia, hypothermia, and organ failure. Manatees typically migrate to warmer water during winter months, but those areas that could once support many manatees in a cold snap no longer have enough seagrass to feed them.
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<img alt="Manatee lies on plank floor and a person holds a tube near his face for feeding" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/tube-feeding_Corduroy.width-990_OFyYUuH.jpg"/>
<figcaption>Newly arrived adult manatee Corduroy is tube-fed at ZooTampa. Image courtesy of ZooTampa
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10:45 a.m. It’s feeding time (again) for the general manatee population housed at the front of the center in two broad pools backed by fake rock walls frequented by very real snowy egrets and great blue herons. Here, meals start at 7:30 a.m. and snacking continues almost without pause all day.On the path between the pools, Intern Olivia Callitsis is unloading heads of endive, escarole, and romaine lettuce from a pallet and stuffing them into a length of PVC pipe with a long hole in the side, so the greens spill out like a planter. A manatee consumes 10%-15% of its body weight daily, and occupants of the two main pools eat through some 1,200 pounds of produce a day. That makes the manatees the most expensive animals to feed at the zoo, costing some $40,000 a month. Burns says the money mostly comes from gate fees and private donors.With a gentle push, Callitsis launches the pipe into the pool, where it bobs gently before sinking. “You can throw it on the surface,” she says of the lettuce, “but this really mimics the natural environment. They have to dive down, work for it a little.” Soon, the surface is broken here and there by smooth gray backs and broad tails, then wrinkly, whiskery snouts munching intently.The inhabitants of the general population pools are mostly at the end of their stay here, with durations that average five months for adults and two years for calves. Because the goal is release, Vaccaro and her colleagues do not engage in the typical zoo enrichment activities, instead switching the manatees between pools frequently so they don’t get too used to their surroundings. And as soon as the calves are stable enough, Vaccaro buddies them up so they learn natural behaviors.
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<img alt="A woman drops a large pipe with protruding lettuce into a manatee pool" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Animal_Care_Professional_Leesa_Whittlef_places.width-990_CV9i266.jpg"/>
<figcaption>Animal Care Professional Leesa Whittlef places a feeder full of lettuce into a critical-care manatee pool at ZooTampa. Image courtesy of ZooTampa
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2:00 p.m. It’s time for the second bottle feeding of the day. Innes and Sauseda carry bottles with a mix of vitamins, baby formula and oils like red palm fruit and macadamia to the medical pools. They lean over and slap the surface to get the calves’ attention and let them know where the goodies are. Small snouts appear and latch onto the bottles, clouds of formula spreading in the water.Burns is aware of the appeal of manatee calves in particular. “Everybody loves manatees and wants to help,” she says of the zoo’s visitors, but they don’t always connect their decisions at home with the fate of the animals they love. “Everyone wants that big, beautiful green lawn, perfectly manicured. But it comes at a cost.”She’s referring to the role nitrates from fertilizers play in <a href="https://www.pbs.org/wgbh/nova/article/florida-red-tide-gulf-coast/">fueling algae blooms</a>, which can block out the sunlight seagrass needs to survive. Similarly, pollution from agricultural runoff, construction, and sewer outflow can cloud coastal waters, starving out seagrass. Sick and dying grass can no longer stabilize the sea floor, which means even more sediment floats up into the water—compounding the situation and giving algae the upper hand, says Lead Biologist Ryan Brushwood of aquatic restoration company Sea &amp; Shoreline. What started as a little algae quickly grows, and ultimately the system hits an inflection point.  
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Some 70 miles north of Tampa, the community of Crystal River saw exactly what that looks like when, in the 1990s, an area that had once hosted some of the state’s largest seagrass meadows was overcome by muck and an algae called Lyngbya wollei. “There was no grass whatsoever,” remembers Lisa Moore, president of the non-profit Save Crystal River. “There were huge plumes of algae growing everywhere.” The water stank; dogs that swam in it got sick. And the population of manatees that had long flocked to the area for its warm springs found little food. In 2015, Save Crystal River hired Sea &amp; Shoreline for a multiyear project: sucking up millions of pounds of muck and water and treating it with a polymer that binds with particles suspended in the water so they become heavier and settle out. The leftover muck is taken to farms to use as fertilizer. Then, Brushwood and his colleagues plant new grass, which they keep in underwater cages to protect it from nibbling manatees until it is well established.Since the plant grows in rhizomes, underground shoots that extend long lateral stems in all directions, it can cover a lot of ground quickly. So far, Save Crystal River has replanted 300,000 plants covering 54 acres out of a planned 92—and those 54 acres have naturally expanded to over 200. The water is clearer, fish and crabs have returned—and so have manatees, in abundance. Save Crystal River hopes its model can be repeated elsewhere in Florida, perhaps including the Indian River Lagoon.  
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<img alt="A woman holds up a funnel and feeding tube that another woman uses to feed a manatee" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Animal_Care_Supervisor_Jaime_Vaccaro_and_Anima.width-990_vLprW02.jpg"/>
<figcaption>Jaime Vaccaro and Sabrina Sauseda tube-feed manatee Kristoff, who has been lifted out of a medical pool with a hydrulic floor for feeding. Image courtesy of ZooTampa
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3:15 p.m. Vaccaro begins shifting manatees around in the medical pools, opening and closing the vertical gates to make space for Pebbles, a mostly-recovered adult who’s been at the center for close to a year. She was in critical condition when she was rescued, with cold stress and propeller wounds that weren’t healing. But she’s made a remarkable recovery and moved into the general population pool not long ago.Pebbles’ bloodwork has recently shown that she might have a brewing infection, though, so she’s receiving antibiotic injections. But after a few days of shots around the same time, Pebbles has figured out the pattern. Vaccaro slips into the water to try to isolate her into medical pool 3 but, in a flash, Pebbles breaks free, using the full force of her tail to twist through the open gate and into the shallow canal that connects the medical and general population pools. Vaccaro radios for help. “She knows she’s going to get an injection, and no one likes those,” Innes says. Instead, Pebbles plays a watery game of cat and mouse. Whenever Vaccaro moves toward her, she glides powerfully to the other side.After half an hour, the staff is on the verge of giving up, aware that Pebbles is stronger than they are. “We try not to force them to do anything they don’t want to do,” Innes says. “But these treatments save their lives, so we have to find that line of when to intervene.”4:25 p.m. As the winter sun starts to dip lower, Vaccaro prepares for the night, loading up PVC pipes full of lettuce and letting whole escarole heads thwap on the surface of medical pool 3 until it’s silty and bobbing with leaves. The buffet of greenery is enough to keep several hungry manatees fed into the wee hours, she reasons—plus, it might tempt Pebbles back into the pool on her own.4:30 p.m. To Vaccaro’s surprise, the tactic works. She moves quickly to drop the gate and hem Pebbles inside. 4:40 p.m. With the floor of medical pool 3 raised all the way up, the heads of lettuce are suddenly beached—and so is Pebbles. Vaccaro and a colleague cover her with a heavy mat, at times using their bodies to keep her steady. The first needle breaks, and Pebbles squirms away, but a second attempt to inject her succeeds. Vaccaro heaves a sigh of relief as Pebbles is lowered back into the pool.
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<img alt="A team loads a large blue sling containing a manatee into a truck" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Loading_Chandler_for_release.width-990_NYhrGgJ.jpg"/>
<figcaption>A manatee named Chandler is loaded for release into the wild in January 2022. Chandler spent a year at ZooTampa's manatee critical care center after being brought in as a juvenile suffering from cold stress. Image courtesy of ZooTampa.
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4:55 p.m. The zoo is closing, but the center’s day never really ends. Vaccaro moves from her antibiotic triumph to mixing up formula for the calves in a cramped office behind the pools, then uses the waning light to tube-feed all three adult manatees in the medical pools in quick succession.When it’s recovering adult Flapjack’s turn, he lies quietly as the slurry of romaine lettuce and formula slips down his throat. He’s gained 70 pounds since he arrived, Sauseda says, showing a photo from the day he arrived with ribs protruding and belly sunken. The difference is still obvious between Flapjack and the other manatees, especially in the definition of his head and the slightness of his torso. But when Vaccaro and Sauseda finish feeding him, his eyes look somehow brighter.Florida made headlines this winter when it went ahead with a controversial program to <a href="https://www.palmbeachpost.com/story/weather/2021/12/08/fwc-oversee-feeding-plan-manatees-starving-death/8887866002/">feed wild manatees</a> in the Indian River Lagoon, in part with the hope of <a href="https://www.mysuncoast.com/2022/03/24/officials-florida-manatees-eat-every-scrap-food-trial/">helping individuals</a> like Flapjack so they don’t need to be treated at places like the center. In Burns’ mind, the most urgent question is how to stop the same thing that’s happened on the state’s Atlantic coast from repeating around Tampa, on the Gulf side. “Let’s learn from this,” she says. “We don’t want to wait for another largest death toll in a year. Let’s get ahead of it and make sure our animals have clean water.” State funds made available for water cleanup are a start, and education is a big part of any solution, she says. But such an urgent and entrenched problem needs a multipronged approach. “You can’t rely solely on education, on rehab, on laws—people break laws all the time. People have to work together in multiple ways to try to solve these problems.”As Flapjack returns to the water, Vaccaro pauses to make sure all her charges are breathing and swimming well after their feeding. She’s also made sure that every manatee has appropriate company overnight—no “busybody” animals that will annoy their poolmates, no males and females that might cause trouble together. Then she walks back to the office for final evening preparations and, eventually, to head home. The center finally lies calm in the half-dark, silent but for the lap of water and occasional hiss of a manatee’s breath. But someone will be back at 10 p.m to feed the calves.
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As Florida’s seagrass beds die off, manatees are starving. Can the seagrass–and the manatees–make a comeback?

Topic: Nature

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