Animals

Slathering corals in a common antibiotic seems to temporarily soothe a mysterious tissue-eating disease, new research suggests.

Just off Florida, a type of coral infected with stony coral tissue loss disease, or SCTLD, showed widespread improvement several months after being treated with amoxicillin, researchers report April 21 in Scientific Reports. While the deadly disease eventually reappeared, the results provide a spot of good news while scientists continue the search for what causes it.

“The antibiotic treatments give the corals a break,” says Erin Shilling, a coral researcher at Florida Atlantic University’s Harbor Branch Oceanographic Institute in Fort Pierce. “It’s very good at halting the lesions it’s applied to.”

Divers discovered SCTLD on reefs near Miami in 2014. Characterized by white lesions that rapidly eat away at coral tissue, the disease plagues nearly all of the Great Florida Reef, which spans 580 kilometers from St. Lucie Inlet in Marin County to Dry Tortugas National Park beyond the Florida Keys. In recent years, SCTLD has spread to reefs in the Caribbean (SN: 7/9/19).

As scientists search for the cause, they are left to treat the lesions through trial and error. Two treatments that show promise involve divers applying a chlorinated epoxy or an amoxicillin paste to infected patches. “We wanted to experimentally assess these techniques to see if they’re as effective as people have been reporting anecdotally,” Shilling says.In April 2019, Shilling and colleagues identified 95 lesions on 32 colonies of great star coral (Montastraea cavernosa) off Florida’s east coast. The scientists dug trenches into the corals around the lesions to separate diseased tissue from healthy tissue, then filled the moats and covered the diseased patches with the antibiotic paste or chlorinated epoxy and monitored the corals over 11 months.

Treatment with an amoxicillin paste (white bands, left) stopped a tissue-eating lesion from spreading over a great star coral colony up to 11 months later (right).E.N. Shilling, I.R. Combs and J.D. Voss/Scientific Reports 2021

Within about three months of the treatment, some 95 percent of infected coral tissues treated with amoxicillin had healed. Meanwhile, only about 20 percent of infected tissue treated with chlorinated epoxy had healed in that time — no better than untreated lesions. 

But a one-and-done treatment doesn’t stop new lesions from popping up over time, the team found. And some key questions remain unanswered, the scientists note, including how the treatment works on larger scales and what, if any, longer-term side effects the antibiotic could have on the corals and their surrounding environment.“Erin’s work is fabulous,” says Karen Neely, a marine biologist at Nova Southeastern University in Fort Lauderdale, Fla. Neely and her colleagues see similar results in their two-year experiment at the Florida National Marine Sanctuary. The researchers used the same amoxicillin paste and chlorinated epoxy treatments on more than 2,300 lesions on upwards of 1,600 coral colonies representing eight species, including great star coral.Those antibiotic treatments were more than 95 percent effective across all species, Neely says. And spot-treating new lesions that popped up after the initial treatment appeared to stop corals from becoming reinfected over time. That study is currently undergoing peer-review in Frontiers in Marine Science.

“Overall, putting these corals in this treatment program saves them,” Neely says. “We don’t get happy endings very often, so that’s a nice one.” More

A Magellanic penguin in Brazil ingested a face mask. A hedgehog in England got itself entangled in a glove. An octopus off the coast of France was found seeking refuge under a mask.

Wildlife and ecosystems around the world are suffering from the impact of discarded single-use COVID-19 protective gear, researchers warn March 22 in Animal Biology. Latex gloves and polypropylene masks which protect people from the coronavirus are exacerbating the plastic pollution problem when not disposed of properly and are causing wildlife deaths (SN:11/20/20). The study is the first global documentation of the impacts of COVID-19 litter on wildlife via entanglement, entrapment and ingestion (SN:12/15/20).

In August 2020, volunteers cleaning canals in Leiden, Netherlands, chanced upon a perch — a type of freshwater fish — trapped inside a finger of a latex glove. The ensnared fish was the first recorded wildlife casualty caused by COVID-19 litter in the Netherlands. The find shocked two Leiden-based biologists — Auke-Florian Hiemstra and Liselotte Rambonnet — who wanted to know more about the extent of COVID-19 litter’s impact on wildlife. They embarked on an extensive search, online and in newspapers, to collate examples.

A perch found trapped in a latex glove (pictured) in a Leiden canal inspired two Dutch biologists to look into how discarded single-use PPE is impacting animals around the world.Auke-Florian Hiemstra

They found 28 such instances from all around the world, pointing to a larger, global problem.   The earliest reported victim was from April 2020: an American robin in Canada, which appears to have died after getting entangled in a face mask. Pets are at risk, too: In Philadelphia, a domestic cat ingested a glove, and a pet dog in Boston that had consumed a face mask. “Animals with plastic in their stomach could starve to death,” says Rambonnet, of Leiden University.

“What this paper does is give us insight to the extent of the [COVID-19] litter’s impact on wildlife, so we can make efforts to minimize the consequences,” says Anna Schwarz, a sustainable plastics researcher at TNO, an independent organization for applied scientific research in Utrecht, Netherlands. That could be a tall order: A report published by Hong Kong–based marine conservation organization OceansAsia, for instance, estimates that 1.56 billion face masks would have entered the world’s ocean last year, part of the 8 million to 12 million metric tons of plastic that reaches the oceans annually.

As the far-reaching impacts of COVID-19 litter on wildlife become more apparent over time, Hiemstra, of the Naturalis Biodiversity Center, and Rambonnet are relying on citizen scientists to help them continue monitoring the situation: At www.covidlitter.com, people from around the world can submit their observations of affected wildlife. To curb the growing hazards, the study authors recommend switching to reusables wherever possible, as well as cutting up disposal gloves and snipping the straps off of single-use masks to prevent animals from getting entangled or trapped in them.

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“The paper highlights the importance of proper waste management, especially the recycling or disposal of single-use materials,” says Schwarz.

But the situation isn’t always so dire. Some animals have commandeered discarded PPE for their own uses. COVID-19 litter has become so pervasive that birds have been observed using face masks and gloves as building materials for their nests. “Bird nests from 2020 are so easy to recognize,” says Hiemstra. More

The open ocean is a veritable soup of tiny critters, including newborn fishes. It’s hard to learn about them, though, because they are mere millimeters long and semitransparent. When netted from research vessels, their delicate body parts may get mashed or removed. Now, a partnership between scientists and scuba divers is giving researchers fresh perspectives on the secrets of larval fishes.

Underwater photos taken at night — when larval fishes migrate to within 200 meters of the ocean surface — reveal colors, body structures and behaviors that could never be seen in preserved specimens. Examining those same fishes back in the lab lets ichthyologists match the photographed larval fishes to known species, researchers report March 30 in Ichthyology & Herpetology.

Scientists at the Smithsonian Institution and the National Oceanic and Atmospheric Administration hatched a collaboration in 2016 with blackwater divers — who enter the ocean in the dark of night — to photograph larval fishes and collect them as specimens. With lights in hand, divers Jeff Milisen and Sarah Mayte snapped up-close photos of nearly 80 larval fishes, then gingerly captured and shipped them to scientists to be studied alongside their mugshots.

“Fish larvae that looked utterly drab as specimens have turned out to have brilliantly colored markings and fantastic structures,” says Ai Nonaka, a larval fish expert at the Smithsonian’s National Museum of Natural History in Washington, D.C.

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Fragile appendages

Specialists like Nonaka sort out larval fish identities by looking at body shapes and minuscule features through microscopes and by analyzing DNA of larval tissue. Unlike their swimming parents, fish larvae drift on currents, and their strange body parts — adaptations for a drifting lifestyle — make larvae look nothing like adults. 

“Larval fishes are extremely difficult to identify,” says Dave Johnson, an ichthyologist also at the Smithsonian. Scientists have mistakenly given larval fishes new scientific names, not recognizing them as early life stages of known species.

Because larval fishes are soft and fragile, they don’t travel well. Larvae lose fins and other delicate structures that evoke their behavior. The scalloped ribbonfish (Zu cristatus) larva, for example, has spaghetti-like ornamental fins sprinkled with white spots that get broken off on specimens. The way these ornamental structures appear to flow out like tentacles in the images of wild larvae suggests the larvae could be jellyfish mimics, say the study authors.

Scalloped ribbonfish (Zu cristatus) larva in the oceanJ. Milisen

Scalloped ribbonfish (Z. cristatus) larva specimenA. Nonaka/Smithsonian NMNH

The trailing guts of a barbeled dragonfish (Aristostomias sp.) larva get mashed or broken off altogether, but the undersea photo reveals it coiled up into a tight corkscrew. Nonaka and Johnson confess that scientists don’t yet understand the function of the trailing guts seen in some larval fishes. One theory is that exposed innards might somehow increase digestion efficiency, while another suggests they could confuse predators.

Barbeled dragonfish (Aristostomias sp.) larva in the oceanJ. Milisen

Barbeled dragonfish (Aristostomias sp.) larva specimenA. Nonaka/Smithsonian NMNH

Hidden colors

Ethanol preservation of specimens repels bacteria and fungi, but leaches out colors. The three-spot righteye flounder (Samariscus triocellatus) larva, bone white as a specimen, is bright blue. Its dorsal and anal fins are fringed with white, and rows of yellow spots dot the base of the fin rays. While their function has yet to be studied, it’s possible that these borders create a flickering visual effect to help the fish escape from predators, suggests Geoff Moser, a retired NOAA fisheries biologist not involved with the study. Called “flicker fusion,” it’s been examined in other animals such as striped snakes as a form of camouflage on the go.

Three-spot righteye flounder (Samariscus triocellatus) larva in the oceanJ. Milisen

Three-spot righteye flounder (S. triocellatus) larva specimenA. Nonaka/Smithsonian NMNH

The deep-sea tripodfish (Bathymicrops sp.) is plain and pale when prepared as a specimen and uniform brown as an adult fish — not exactly a looker. But the larva appears to have donned a clown costume with large white and orange polka dots flecked on its otherwise blue-hued body. In an ethanol specimen, its pectoral fins look soft and ghostly, whereas the living larva sports flamboyant, spiky and spotted fins. The function of the coloration is unknown. says Nonaka, but it could also be a flicker fusion trick.

Deep-sea tripodfish (Bathymicrops sp.) larva in the oceanJ. Milisen

Deep-sea tripodfish (Bathymicrops sp.) larva specimenA. Nonaka/Smithsonian NMNH

Fishy behavior

In larval specimens, scientists can observe some structures as evidence of behaviors. But undersea observations of wild larval fishes can show what they’re really up to when they are alive. The larva of the barred conger (Ariosoma fasciatum) is super flat, quite unlike the cylindrical adult. Yet a photo shows that it swims like an adult barred conger, by undulating its long body laterally. So, while it’s more svelte as a larva, it’s got some of the adult movements down.

Barred conger (Ariosoma fasciatum) larva in the oceanJ. Milisen

Barred conger (A. fasciatum) larva specimenA. Nonaka/Smithsonian NMNH

Undersea observations can also reveal associations larvae have with other marine animals, including other tiny critters that also ride the currents. For example, a petite Pacific pomfret (Brama japonica) larva was caught on camera riding on a jellyfish. That’s a discovery that the study authors were unwilling to even speculate about. Although larval fishes have been seen taking shelter in the tentacles of jellies, hitching a ride on top of a jellyfish seems like an odd twist on that behavior.

A pacific pomfret (Brama japonica) larva (pictured from three angles) in the ocean, riding a jellyfishJ. Milisen (photos); E. Otwell/Science News (collage)

Pacific pomfret (Brama japonica) larva specimenA. Nonaka/Smithsonian NMNH

Each larval fish that gets identified by scientists sets the stage for conservation. By knowing where larval fishes of particular species live, researchers can better advise on how to manage the ocean ecosystems the fishes depend on for survival.

Conservation planning also requires knowledge of behavior (SN: 12/30/10). So photographing larval fishes and making their specimens available for identification means researchers get a handle on fishes’ behavioral adaptations for survival in the wild.

“I’ve been working with fish larvae for over 40 years,” says Moser. “The chance to see these larvae in their environment was a wonderful advance in our scientific endeavors.” More

When Isabel Hyman heads out in coming weeks to the wilds of northern New South Wales, she’s worried about what she won’t find. Fifteen years ago, the malacologist — or mollusk scientist — with the Australian Museum made an incredible discovery among the limestone outcrops there: a tiny, 3-millimeter-long snail, with a ribbed, dark golden-brown shell, that was new to science.
Subsequently named after her husband, Hugh Palethorpe, Palethorpe’s pinwheel snail (Rophodon palethorpei) “is only known from a single location, at the Kunderang Brook limestone outcrops in Werrikimbe National Park,” she says. Now it may become known for a different, more devastating distinction: It is one of hundreds of species that experts fear have been pushed close to, or right over, the precipice of extinction by the wildfires that blazed across more than 10 million hectares of southeastern Australia in the summer of 2019–2020.
“This location was completely burnt,” says Hyman, who is based in Sydney. “We expect the mortality at this site could be very high and … there is a possibility this species is extinct.”
A year after the last of the fires were doused, their toll on species is becoming increasingly clear.  Flames devoured more than 20 percent of Australia’s entire forest cover, according to a February 2020 analysis in Nature Climate Change. Even if plants and animals survived the flames, their habitats may have been so changed that their survival is at risk (SN: 2/11/20). As a result of the scale of the disaster, experts say that more than 500 species of plants and animals may now be endangered — or even completely gone. 
A wallaby licks its burnt paws after escaping a bushfire near Nana Glen in New South Wales on November 12, 2019.Wolter Peeters/The Sydney Morning Herald via Getty Image
Australia’s iconic koala became the poster child of the crisis as images of rescuers carrying these singed marsupials out of the flames went global: As many as 60,000 of the nation’s estimated population of 330,000 koalas perished in the fires, ecologists concluded in December in a report for World Wildlife Fund Australia. While there’s no doubt that such charismatic megafauna suffered enormously, the greatest toll is likely to have been in other groups of species, such as invertebrates and plants, which often escape the public’s attention.
As Kingsley Dixon, an ecologist at Curtin University in Perth told the Associated Press last year: “I don’t think we’ve seen a single event in Australia that has destroyed so much habitat and pushed so many creatures to the very brink of extinction.”

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Koala charisma
Even before the fires, many vertebrate species were already on downward trends, says John Woinarski, an ecologist at Charles Darwin University in Darwin. The blazes have “exacerbated the threats that were driving the declines,” he says.
For example, fluffy arboreal marsupials called greater gliders (Petauroides volans) had already experienced a 50 percent population decline in recent decades. The fires then burned a third of their remaining habitat along Australia’s eastern coastline. An ongoing assessment may lead to the gliders being recategorized from vulnerable to endangered.
Overall, 49 vertebrates that previously were not endangered now qualify for being listed as threatened under Australia’s guidelines for that designation, researchers reported in July in Nature Ecology and Evolution. That shift alone would increase the tally of nationally protected nonmarine vertebrate species by about 15 percent, from 324 to 373.
Another 21 already threatened vertebrates had more than 30 percent of their ranges burned, and some may now qualify for being reassessed to higher categories of threat, the authors found. One species that may need to be recategorized is the koala (Phascolarctos cinereas), with some state’s populations that were hardest hit under consideration to be upgraded from vulnerable to endangered. 
A koala named Paul recovers from his burns at an ICU in November 2019 after being rescued by volunteers following weeks of bushfires across New South Wales and Queensland.Edwards/Getty Image
Besides the impact on koalas, the WWF Australia report suggests that as many as 3 billion individual mammals, birds, reptiles and frogs died or were displaced during the crisis. Though those figures are astounding, the impacts on lesser-studied groups such as invertebrates and plants may have been even greater.
“Many of those have much smaller ranges [than vertebrates], which means they are going to be even more impacted when a big fire goes through,” says James Watson, a conservation scientist at the University of Queensland in Brisbane and an author of the Nature Ecology and Evolution paper on vertebrates. “I am willing to bet that there’s many species … that may disappear forever.”
Invertebrate impact
In February, more than 100 biologists convened the first of several online workshops to assess whether 234 Australian invertebrates now need to be added to the International Union for the Conservation of Nature’s Red List — a global who’s who of threatened species. 
Snails, similar to many invertebrates, are particularly susceptible to wildfires, as they are unable to outrun flames and can’t survive intense heat, Hyman notes. Many also have small ranges that were completely incinerated, leaving no survivors that can recolonize the burned area.
“A snail can’t do much to escape,” she says. “You could expect more than 90 percent mortality in a high-intensity bushfire.” In October, Hyman’s team published one of the first papers quantifying the impacts on invertebrates in New South Wales in the Technical Reports of the Australian Museum Online.
The Palethorpe’s pinwheel snail (Rophodon palethorpei) has not yet turned up in searches following the wildfires, but other snail species did survive.Vince Railton, Queensland Museum
Their surveys showed that 29 species in the state — including dung beetles, freshwater crayfish, flies, snails and spiders — had their entire ranges burned. Another 46 species had at least half their known habitat within the fire zones. These 75 species were among the 234 under consideration for adding to the IUCN Red List during the biologists’ first online workshop.
“We’ve gathered together 230-odd species that are believed to now be of concern. These include a range of different taxa from land snails to millipedes to arachnids to insects, and this 230 is growing rapidly,” says Jess Marsh, an arachnologist at Charles Darwin University who was one of the conveners of the workshop. “I expect it will massively increase.”
Some of the spiders she studies were the first to be added to that list. She’s already spent several months on South Australia’s Kangaroo Island hunting without luck for the Kangaroo Island assassin spider (Zephyrarchaea austini). Dependent on leaf litter suspended in the understory, and restricted to just a few locations that were razed in early 2020, she suspects that the species may be extinct.
Spiders on Kangaroo Island such as this assassin spider (Zephyrarchaea austini) may now be extinct after most of their habitat was razed in early 2020.M.G. Rix and M.S. Harvey/ZooKeys 2012
“There’s no understory vegetation left, let alone any leaf litter suspended in it, so that species is really hanging in the balance,” says Marsh.
Generally, the species being considered for recognition as endangered had more than 50 percent of their ranges burned, lived in flammable parts of the habitat and have little ability to disperse to other areas. More than 150 of the 234 species being urgently assessed had their entire range burned. And it’s not just the flames themselves that are problematic; so is the reshaped environment following fires. Millipedes, for example, are very vulnerable not only to fire but also to drying out in the reduced shade and shelter of the post-fire environment.
“A lot of invertebrates are very susceptible to desiccation, and need cover and humidity to survive a hot summer, which are obviously lacking following the fire,” Marsh says. “Taking into account all of the threats … we could be looking at significant numbers going extinct.”
Rooted in place
Lost vegetation hasn’t just put animals in danger. Many plants themselves may also be at risk, though experts have yet to compile an official list.
Rachael Gallagher, a plant ecologist at Macquarie University in Sydney, has been prioritizing endemic plant species — those found nowhere else on Earth — that are in most urgent need of conservation for the Australian government. Perhaps surprisingly, she’s particularly worried about some trees that actually depend on fire to survive. Eucalypts known as alpine ash (Eucalyptus delegatensis) and mountain ash (E. regnans), for instance, are typically killed by fire and then regenerate from surviving seeds in the aftermath. Australia has many trees that must complete their entire life cycle from germination through to reproductively mature adult before the next major bushfire passes through (SN: 2/11/20). For some species, this may take 15 to 20 years.
Some trees in Australia, such as this mountain ash (Eucalyptus regnans), depend on fire for their lifecycle, but recent wildfires may have been too much too soon.station96/iStock/Getty Images Plus
The problem now is that climate change has increased the frequency of fires to the degree that many of these plants are unable to reach adulthood and set seed before the next fire passes through, meaning they may be lost from these ecosystems (SN: 3/4/20).
The fires burned 25–100 percent of the ranges of 257 species of plants for which “the historical intervals between fire events across their range are likely to be too short to allow them to effectively regenerate,” Gallagher says. These species, which have some degree of fire tolerance, are at “increased risk of extinction.” These include shrubs and trees such as the granite boronia (Boronia granitica), Forrester’s bottlebrush (Callistemon forresterae), dwarf cypress pine (Callitris oblonga) and the Wolgan snow gum (Eucalyptus gregsoniana).
Found, not lost
Nevertheless, as researchers head out into the field to assess what’s lost, what they are sometimes finding are glimmers of hope. “Australian plants are remarkably resilient and there’s been regeneration in places where nobody thought there would be,” Gallagher says.
One species that survived against all the odds is the Gibraltar Range waratah (Telopea aspera), a drought-resistant shrub with leathery leaves and bright red flowers. “This species has a very small range, being specialized to granite outcrops in one mountain range, which was burnt during the fires,” she says. “However, it has been noted as resprouting after the fires by park rangers and, in the absence of another fire in coming years, is likely to be able to recover.”
Several animal species that were thought to be in grave peril following the fires that burned nearly half of the 4,400-square-kilometer Kangaroo Island have survived better than expected too (SN: 1/13/20). In the particularly badly burned reserves of the western end of the island, tiny marsupial carnivores called Kangaroo Island dunnarts (Sminthopsis aitkeni) are frequently appearing on camera traps. Swiftly erected predator-exclusion fences now protect survivors from feral cats.
Tiny marsupials known as Kangaroo Island dunnarts (Sminthopsis aitkeni) have fared much better than other animals, appearing frequently on camera traps.Australian Wildlife Conservancy
Similarly, large flocks of the glossy black-cockatoo (Calyptorhynchus lathami) have adapted by moving to unburned areas with food trees, says Karleah Berris of Natural Resources Kangaroo Island, who heads the crew that manages the endangered birds. Better news yet, a surprising number of birds bred and fledged young in mid-2020. “The important thing now is to protect what is left from fire until the burnt areas regenerate,” she says. “But I think, at present, all signs are that they are coping.”
Hyman says that, hearteningly, her team found handfuls of survivors of some snail species during several surveys in New South Wales in late 2020. The snails turned up in small patches of unburned habitat, sometimes at the bottom of gullies or in deep leaf litter around the bases of large trees. And that gives her hope that other snail species may have held on in other, larger unburned patches with greater numbers of survivors.
“But the question then becomes, what sort of recovery can they make from that?” she says. “Whether they can recover and breed up and start to move back into surviving areas again perhaps depends on how dry the weather is in coming years and if there are more fires.”
She’s still hoping that a handful of Palethorpe’s pinwheel snails may have clung on against all the odds. “My husband is on tenterhooks wondering if his snail is still there or not,” she says. More

The mysterious culprit behind a deadly sea star disease is not an infection, as scientists once thought.
Instead, multiple types of bacteria living within millimeters of sea stars’ skin deplete oxygen from the water and effectively suffocate the animals, researchers report January 6 in Frontiers in Microbiology. Such microbes thrive when there are high levels of organic matter in warm water and create a low oxygen environment that can make sea stars melt in a puddle of slime.
Sea star wasting disease — which causes lethal symptoms like decaying tissue and loss of limbs — first gained notoriety in 2013 when sea stars living off the U.S. Pacific Coast died in massive numbers. Outbreaks of the disease had also occurred before 2013, but never at such a large scale.
Scientists suspected that a virus or bacterium might be making sea stars sick. That hypothesis was supported in a 2014 study that found unhealthy animals may have been infected by a virus (SN: 11/19/14). But the link vanished when subsequent studies found no relationship between the virus and dying sea stars, leaving researchers perplexed (SN: 5/5/16). 

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The new finding that a boom of nutrient-loving bacteria can drain oxygen from the water and cause wasting disease “challenges us to think that there might not always be a single pathogen or a smoking gun,” says Melissa Pespeni, a biologist at the University of Vermont in Burlington who was not involved in the work. Such a complex environmental scenario for killing sea stars “is a new kind of idea for [disease] transmission.”  
There were certainly many red herrings during the hunt for why sea stars along North America’s Pacific Coast were melting into goo, says Ian Hewson, a marine biologist at Cornell University. In addition to the original hypothesis of a viral cause for sea star wasting disease — which Hewson’s team reported in 2014 in Proceedings of the National Academy of Sciences but later disproved — he and colleagues analyzed a range of other explanations, from differences in water temperature to exposing the animals to bacteria. But nothing reliably triggered wasting.   
Then the researchers examined the types of bacteria living with healthy sea stars compared with those living among the animals with wasting disease. “That was when we had our aha moment,” says Hewson.
Not all sea stars are susceptible to sea star wasting disease. Species that have more structures on their surface, and therefore more surface area for bacteria to deplete oxygen, appear more likely to get severely sick compared with flatter sea stars. In this photo, an ochre sea star (Pisaster ochraceus) succumbs to the disease in Davenport, Calif., in June 2018.Ian Hewson
Types of bacteria known as copiotrophs, which thrive in environments with lots of nutrients, were present around the sea stars at higher levels than normal either shortly before the animals developed lesions or as they did so, Hewson and colleagues found. Bacterial species that survive only in environments with little to no oxygen were also thriving. In the lab, the sea stars began wasting when the researchers added phytoplankton or a common bacterial-growth ingredient to the warm water tubs those microbes and sea stars were living in.  
Experimentally depleting oxygen from the water had a similar effect, causing lesions in 75 percent of the animals, while none succumbed in the control group. Sea stars breathe by diffusing oxygen over small external projections called skin gills, so the lack of oxygen in the wake of flourishing copiotrophs leaves sea stars struggling for air, the data show. It’s unclear how the animals degrade in low oxygen conditions, but it could be due to massive cell death.
Although the disease isn’t caused by a contagious pathogen, it is transmissible in the sense that dying sea stars generate more organic matter that spur bacteria to grow on healthy animals nearby. “It’s a bit of a snowball effect,” Hewson says.
The team also analyzed tissues from sea stars that had succumbed in the 2013 mass die-off — which followed a large algal bloom on the U.S. West Coast — to see if such environmental conditions might explain that outbreak. In fast-growing appendages that help them move, the sea stars that perished had high amounts of a form of nitrogen found in low oxygen conditions — a sign that those animals may have died from a lack of oxygen.
The problem may get worse with climate change, Hewson says. “Warmer waters can’t have as much oxygen [compared with colder water] just by physics alone.” Bacteria, including copiotrophs, also flourish in warm water.  
But pinpointing the likely cause could help experts better treat sick sea stars in the lab, Hewson says. Some techniques include increasing the oxygen levels in a water tank to make the gas more easily available to sea stars or getting rid of extra organic matter with ultraviolet light or water exchange.
“There’s still a lot to figure out with this disease, but I think [this new study] gets us a long way to understanding how it comes about,” Pespeni says. More

Marcus Eriksen was studying plastic pollution in the Arabian Gulf when he met camel expert Ulrich Wernery. “[Ulrich] said, ‘You want to see plastic? Come with me.’ So we went deep into the desert,” Eriksen recalls. Before long, they spotted a camel skeleton and began to dig through sand and bones.
“We unearthed this mass of plastic, and I was just appalled. I couldn’t believe that — almost did not believe that — a mass as big as a medium-sized suitcase, all plastic bags, could be inside the rib cage of this [camel] carcass,” says Eriksen, an environmental scientist at the 5 Gyres Institute, a plastic pollution research and education organization in Santa Monica, Calif.
“We hear about marine mammals, sea lions, whales, turtles and seabirds impacted” by plastic waste, Eriksen says (SN: 6/6/19). But “this is not just an ocean issue. It’s a land issue, too. It’s everywhere.”
About 390,000 dromedary camels (Camelus dromedarius) live in the United Arab Emirates. Now in a study in the February 2021 Journal of Arid Environments, Eriksen, Wernery and colleagues estimate that plastic kills around 1 percent of these culturally important animals.
Of 30,000 dead camels that Wernery, a veterinary microbiologist at the Central Veterinary Research Laboratory in Dubai, and his team have examined since 2008, 300 had guts packed with plastic ranging from three to 64 kilograms. The researchers dubbed these plastic masses “polybezoars” to distinguish them from naturally occurring hair and plant fiber bezoars.
When camels eat plastic, it accumulates into enormous, stomach-clogging masses called polybezoars. Researchers found these polybezoars — the biggest of which weighs almost 64 kilograms — inside dead camels in the desert near Dubai.M. Eriksen et al/J. Arid Enviro. 2021
When camels eat plastic, it accumulates into enormous, stomach-clogging masses called polybezoars. Researchers found these polybezoars — the biggest of which weighs almost 64 kilograms — inside dead camels in the desert near Dubai.M. Eriksen et al/J. Arid Enviro. 2021
As dromedaries roam the desert looking for food, they munch on plastic bags and other trash that drift into trees and pile up along roadsides. “From the camel’s perspective … if it’s not sand, it’s food,” Eriksen says.
With a stomach full of plastic, camels don’t eat because they don’t feel hungry, and they starve to death. Plastic can also leach toxins and introduce bacteria that poison the one-humped mammals, Wernery says.

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“If 1 percent mortality due to plastic is verified by future and more detailed studies, then plastic pollution will certainly represent a reason of concern for [camels],” says Luca Nizzetto, an environmental scientist at the Norwegian Institute for Water Research in Oslo, who was not involved with the research. “These types of studies are relevant to raise social awareness about this pollution.”
Banning plastic bags and single-use plastics is crucial for protecting camels and other wildlife, Eriksen says. “Plastic bags are escape artists. They blow out of garbage cans, out of landfills, out of trucks and out of people’s hands. They travel for hundreds of miles.” More

After the coldest night in south Florida in a decade, lizards were dropping out of palm trees, landing legs up. The scientists who raced to investigate the fallen reptiles have now found that, despite such graceless falls, some of these tropical, cold-blooded creatures are actually more resilient to cold than previously thought.
The finding sheds light on how some species might respond to extreme weather events caused by human-caused climate change (SN: 12/10/19). Although climate change is expected to include gradual warming globally, scientists think that extreme events such as heat waves, cold snaps, droughts and torrential downpours could also grow in number and strength over time.
The idea for the new study was born after evolutionary ecologist James Stroud received a photo of a roughly 60-centimeter-long iguana prone on its back on a sidewalk from a friend in Key Biscayne, an island town south of Miami. The previous night, temperatures dropped to just under 4.4° Celsius (40° Fahrenheit).
“When air temperatures drop below a critical limit, lizards lose the ability to move,” says Stroud, of Washington University in St. Louis. Lizards that sleep in trees “may lose their grip.” Stunned lizards on the ground are likely easy prey for predators, he notes.

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Realizing that the cold snap could be used to study how future instances of extreme weather might affect such animals in the wild, Stroud and colleagues rushed to collect live specimens of as many different kinds of lizards as they could in the Miami area (SN: 8/27/20). The researchers then tested how well the six reptile species they captured tolerated cold by sticking thermometers on the animals, placing them in a large cooler of ice and observing how cold they got before becoming too stunned to right themselves after getting flipped on their backs.
Stroud and colleagues had previously run similar tests on these lizard species as part of research on invasive species. That work in 2016 suggested that the reptiles might not easily withstand cold snaps like the recent one — cold tolerances ranged from as low as about 7.7° C for the Puerto Rican crested anole (Anolis cristatellus) to roughly 11.1° C for the brown basilisk (Basiliscus vittatus).
Some tropical, cold-blooded lizards, such as this brown basilisk (Basiliscus vittatus), are more resilient to cold than previously thought, a new study finds.John Sullivan/iNaturalist (CC BY-NC 4.0)
The new study, however, revealed that the reptiles now could withstand temperatures roughly 1 to 4 degrees C colder. Oddly, the lizards, on average, could all endure cold down to the same lowest temperature, about 5.5° C, the researchers report in the October Biology Letters. Given the great variation in size, ecology and physiology between these species, “this was a really unexpected result,” and one that the researchers don’t have an explanation for, Stroud says.
Natural selection may be behind the change, meaning that abnormally cold temperatures are killing off those individuals that could not survive and leaving behind those that happen to be better able to tolerate cold. Alternatively, the reptiles’ bodies could have changed in some way to acclimate to the colder temperatures. Stroud hopes in the future to measure the cold tolerance of lizards immediately before a forecasted cold snap and then examine the same reptiles immediately afterward to look for signs of acclimation.
Scientists have long thought that tropical species, which have typically evolved in thermally stable environments, might prove especially vulnerable to major shifts in temperature (SN: 5/20/15). This new study reveals a way in which species can either rapidly evolve or acclimate, which “may provide ecosystems with some resilience to extreme climate events,” says Alex Pigot, an ecologist at University College London who did not take part in the research.
One remaining question “is whether this resilience also applies to extreme heating events,” Pigot adds. “Previous evidence has suggested that species’ upper thermal limits may be less flexible than their lower thermal limits.” More