Animals

Pooping whales changed the course of Asha de Vos’ career.

The Sri Lankan marine biologist was aboard a research vessel near her home island in 2003 when she spotted six blue whales congregating. A bright red plume of whale waste was spreading across the water’s surface.

Seeing whale poop, colored red thanks to the whale’s diet, was the first clue that Sri Lanka’s blue whales don’t migrate between feeding and breeding areas.A. de Vos

De Vos, then a master’s student, recalls being “super excited.” What she witnessed went against prevailing dogma: Her textbooks and professors had taught that blue whales, like other large whales, embark on long-distance migrations between colder feeding areas and warmer breeding and calving areas. But seeing whales pooping in tropical waters meant the behemoths must be feasting locally.

Intrigued, de Vos spent the next few years documenting how blue whales near Sri Lanka differ from those elsewhere in the world. For one, the population feeds on shrimp rather than krill. The whales also have unique songs. But the key difference, she realized, is that they remain year-round in the waters between Sri Lanka, Oman and the Maldives — making them the only nonmigratory blue whales in the world. Abundant upwellings of nutrient-rich water from the ocean depths support a steady food supply for the whales.

Eventually, the International Whaling Commission, the intergovernmental body dedicated to protecting whales, recognized Sri Lanka’s blue whales as a distinct subspecies called Balaenoptera musculus indica.

By studying the blue whales around Sri Lanka, marine biologist Asha de Vos discovered they are the only nonmigratory blue whales in the world.Franco Banfi/Nature Picture Library/Alamy Stock Photo

This distinction is crucial for conservation management, explains retired whale biologist Phillip Clapham, formerly of the U.S. National Oceanic and Atmospheric Administration’s National Marine Fisheries Service. Small, localized populations — like the one in Sri Lanka — face higher risks of being wiped out in the face of environmental or human threats, such as deep-sea mining.

More than two decades on, de Vos is now one of Sri Lanka’s most renowned scientists — famed for nurturing the country’s nascent marine biology scene. She is also an ardent champion for greater diversity among researchers in ocean conservation. More

Some tadpoles don’t poop for the first weeks of their lives. At least, that’s the case for Eiffinger’s tree frogs (Kurixalus eiffingeri), scientists report September 22 in Ecology.

Eiffinger’s tree frogs are tiny frogs that live in Taiwan and on two Japanese islands: Ishigaki and Iriomote. The tree-dwelling amphibians lay their eggs in puny puddles, which are often nestled in plant stems, tree hollows and bamboo stumps.

Once the tadpoles hatch, they spend their early lives in these puddles. However, in pools as small as these, there’s not a lot of water to dilute ammonia — a toxic chemical animals release when they pee or poop.

Bun Ito and Yasukazu Okada, biologists from Nagoya University in Japan, now have uncovered the tadpoles’ secret sanitation strategy — self-induced constipation. The tadpoles store their poop in an intestinal pouch until they start to metamorphize into full-fledged frogs.

The tadpoles of Eiffinger’s tree frogs (Kurixalus eiffingeri) spend their first few weeks of life in tiny puddles of water nestled within tree hollows and bamboo stumps.Bun Ito

Ito and Okada raised tadpoles from four different frog species in makeshift nurseries. Once the experiment began, they moved the tadpoles to smaller cribs, plastic cases with a little more than a tablespoon of water. The team measured and compared how much ammonia each species released. They also measured the amount of ammonia each species stored in their guts.

Eiffinger’s tree frog tadpoles released less than half as much ammonia on average than the species that released the most. And compared with two of the other species, the tadpoles kept more ammonia in their guts. The researchers note that unlike Eiffinger’s tree frogs, the other species typically lay their eggs in open ponds where ammonia is easily diluted. More

In 1998, at the age of 22, conservation biologist Ximena Velez-Liendo came face-to-face with South America’s largest carnivore on her first day of field research in Bolivia. Her life changed forever when she turned around to see “this beautiful, amazing bear coming out of the forest,” Velez-Liendo says. “It was like love at first sight.” She thought in that moment: “If I can do anything for you, I’ll do it.”

Also known as spectacled bears, Andean bears are easily recognized by the ring of pale fur that often encircles one or both eyes. Bolivia is home to about 3,000 adult bears, or roughly one-third of the world’s total Andean bears, whose range arcs through five countries along the western edge of South America. Listed as vulnerable by the International Union for Conservation of Nature, or IUCN, the species (Tremarctos ornatus) suffers mainly from habitat loss and conflicts with humans, who sometimes kill the bears in retaliation when bears raid crops or hunt livestock. More

McKenzie Prillaman was the Spring 2023 science writing intern at Science News. She holds a bachelor’s degree in neuroscience with a minor in bioethics from the University of Virginia and a master’s degree in science communication from the University of California, Santa Cruz. More

Despite the sensationalized portrayal of sharks in movies like Jaws, the ocean’s apex predators have far more to fear from people than vice versa.

Even though millions of people around the world swim in the ocean each year, just 91 people were bitten by sharks in 2023 and only 10 of those bites were fatal, according to a new report from the Florida Museum of Natural History in Gainesville. Out of all bites, 69 were unprovoked while 22 were provoked, defined as a human-initiated interaction such as trying to touch or feed a shark. These numbers — reported by beach safety officers, hospital staff and other emergency responders — are consistent with the five-year global average. More

How do you look for an animal you don’t even know exists anymore?

The last sighting of the purple-winged ground dove (Paraclaravis geoffroyi) — a small, bamboo-loving dove native to the South American Atlantic Forest in Brazil, Argentina and Paraguay — was in 1985. But, researchers wondered, was it possible to capture the elusive bird’s sound in the wild to find out if any individuals are left?

It’s not an unheard-of idea. Scientists have used bioacoustics — a subfield of ecology that relies on sound to make environmental analyses — for everything from recording dolphins’ communication patterns to studying bats from afar to avoid virus spillover from humans (SN: 12/7/17; SN: 10/23/22). With artificial intelligence, it is now possible to use large audio datasets to train algorithms to spot different animal sounds within the cacophony of a natural background.

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But the problem is that recordings of the purple-winged ground dove singing are as rare as the bird itself.

“I came across [the bird’s song] watching a 1985 interview with Carlos Keller, a former bird breeder in São Paulo state, who had a few individuals of the dove,” says Carlos Araújo, an ecologist at the Instituto de Biología Subtropical at the Universidad Nacional de Misiones in Argentina. “And they sang while he spoke.”

With Keller’s help, Araujo and colleagues accessed the decades-old recording and isolated the bird’s song.

The next challenge was to see if it was even possible to identify individual bird songs amidst the sounds of other birds chirping, leaves rustling, rain falling, insects whirring and gnawing and larger animals moving through the forest.

“We took a step back and did some analyses with other birds that are critically endangered but there are known individuals,” Araújo says. The team focused on three species found in Foz do Iguaçu, a national park that straddles the border of Brazil and Argentina: the cherry-throated tanager (Nemosia rourei), the Alagoas antwren (Myrmotherula snowi) and the blue-eyed ground-dove (Columbina cyanopis). These birds live in the same environments as the purple-winged ground dove. And the blue-eyed ground dove’s story inspires hope: The species went missing in 1941 and was rediscovered in 2016.

To test their setup, the researchers looked for the cherry-throated tanager (shown) and two other rare birds.Ben Phalan/Parque das Aves

The researchers installed 30 recorders in strategic spots along green areas in the Brazilian part of Foz do Iguaçu and recorded from July 2021 to April 2022. They also used data from another 100 recorders on the Argentinian side of Foz.

“We went looking for the Guadua trinii bamboo to place the recorders,” says Benjamin Phalan, Head of Conservation at Parque das Aves, a private institution in Foz do Iguaçu focused on the conservation of Atlantic Forest birds. Like the purple-winged ground dove, the three bird species follow the flowering season of the G. trinii bamboo, which happens about once every 30 years.

The team pushed through thickets of bamboo, braved ticks and biting flies, and watched out for venomous snakes such as jacaracas pit vipers. Bumping into these snakes is “rare but can happen. So we use galoshes or gaiters to protect us in case anyone steps on a snake or near it,” Phalan says.

Carlos de Araujo installs a recording device in a South American forest. He and colleagues hope to pluck the song of rare birds out of the forest sounds the device picks up. Ben Phalan/Parque das Aves

The recorders captured one minute of landscape sound every 10 minutes and generated about 3,000 days’ worth of recordings. “A lot of data to sift through,” says Araújo.

Readily available analysis software wouldn’t work. These software, Araújo says, “need a lot of data input. With such rare species, we just don’t have that much data to train the identification algorithm.”

So the team started from scratch, working with the little data they had for the three endangered birds. First, Araújo created a signal template — exactly like the birds’ singing — based on just a few recordings. The algorithm then compares that template with the soundscape recordings, separating signal from noise. If it spots a sound that is similar to the template, chances are that it is the bird that the researchers are looking for.

The method relies on a statistical model “that is not new, but was used in a very clever and unusual way,” says David Donoso, an ecosystem ecology researcher at the Technische Universität Darmstadt in Germany. Donoso and colleagues recently used bioacoustics to investigate the recovery of Choco, a biodiversity hot spot in Ecuador that had been transformed in an agricultural area.

There are different approaches to bioacoustics depending on what you’re looking for, Donoso says. “You can either use fewer recordings to map a whole animal soundscape to tell what species are there, like we did, or you can use lots of recordings to look for a single sound pattern,” he says. The study at Foz do Iguaçu “shows that you can use a relatively simple model to answer a complex question — and it works.”

The tool worked reasonably well to identify the cherry-throated tanager and blue-eyed ground-dove singing, but not so much for the Alagoas antwren, Araújo’s team reports October 23 in Bioacoustics. “We’re trying to understand what happened, but we know that the algorithm works,” he says.

The next step, Araújo says, is to refine the algorithm’s precision to find the Alagoas antwren and train it to look for the purple-winged ground dove. And they will do so at the same time. “We’re aiming at both goals at once because we’re running against the clock to find these birds,” Araújo says. “In the end, we are looking for a ghost.” But not a silent one, he hopes.  More

Erinn Muller should have reason to despair. The marine biologist studies coral health in Florida, a state whose reefs have been devastated by extreme heat, increasingly ferocious hurricanes and deadly infectious diseases (SN: 6/15/23; SN: 9/13/23; SN: 7/9/19).

“We’ve lost 98 percent of our living coral cover,” says Muller, of the Mote Marine Laboratory in Sarasota, Fla. While among the hardest hit, Florida isn’t alone. From Australia’s Great Barrier Reef to the Caribbean, coral reefs globally are in trouble.

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But innovative efforts to protect and restore coral reefs buoy Muller’s hopes. She just has to visit Mote’s Caribbean king crab nursery, a project of reef restoration expert Jason Spadaro. There, tiny specks of crustaceans will grow into salad-loving foragers. Once they are set loose on nearby reefs, Maguimithrax spinosissimus eat away suffocating seaweed.

“I’m optimistic because there is really truly so much work being done” to restore coral reefs, says Tali Vardi, a marine biologist and executive director of the Coral Restoration Consortium, a global community of scientists, managers and restoration experts dedicated to helping coral reefs. While safeguarding the future of coral reefs ultimately depends on halting climate change, “we’re trying to maintain pockets of biodiversity” that can serve as a springboard for the long-term recovery of reefs.

Given how diverse coral reefs are, Vardi says, researchers need a diversity of solutions to match. “There’s no silver bullet here.”

Around the globe, coral biologists are trying everything from low-tech seaweed removal to high-tech artificial fog production to protect corals. Here’s a closer look at three projects that researchers are developing to help save coral reefs.

Sea-weeding, literally

In Australia’s Great Barrier Reef, it’s not crabs doing the weeding. It’s volunteers with Earthwatch Institute — an international environmental organization — snorkeling and diving underwater to pluck macroalgae, the weed of the sea. The volunteers’ goal is to free parts of the reef from a seaweed scourge to see if that leads to a resurgence in coral.

“There’s been this issue with increases in macroalgae versus corals for a long time,” says David Bourne. “If something’s out of whack” with the reef ecosystem, “the corals lose out and the macroalgae take over.”

Though they seem like a cross between plants and rocks, the hard corals that form reefs are actually giant colonies of tiny animals called coral polyps. The polyps secrete a hard skeleton made of calcium carbonate, and skeleton by skeleton, they build an undersea city. Tiny photosynthetic algae partners living inside the polyps give the corals their brilliant colors and generate energy for their hosts.

Seaweed, however, takes up space and soaks up light that could otherwise be used by corals. If corals decline in number due to stressors like heat or disease, seaweed can quickly proliferate and take their place.

Bourne, a marine biologist at James Cook University in Townsville, Australia, wanted to know if the seaweed-removal program being run by Earthwatch was effective. From 2018 to 2021, volunteers pruned seaweed from 24 sections of the reef — each 5 meters by 5 meters — several times per year, while leaving other seaweed-laden areas alone. In total, they removed a whopping 2,148 kilograms of seaweed.

At the start, the tended plots had enough corals to cover only about 34 square meters. Removing macroalgae from those plots led to a total gain of nearly 203 square meters of coral cover, enough to blanket a tennis court, Bourne’s team reported September 13 in the Journal of Applied Ecology. This change wasn’t seen in the plots left unpruned.

After volunteers removed suffocating seaweed from sections of Australia’s Great Barrier Reef, coral cover expanded dramatically in just a few years. These photos show the same part of the reef in May 2019 and May 2023.Hillary Smith

“It’s not surprising that we saw some recovery,” Bourne says. “What was surprising was the amount of recovery and how quickly it happened.” Sea-weeding is a straightforward way to skew the reef’s competitive balance and help corals thrive, he says.

Bourne hopes the simplicity of the approach will help it spread. “The advantage of sea-weeding is it’s really low tech; anybody can do it,” he says. Plus, seaweed tends to be an issue on reefs that are close to shore and known to local communities, “so there’s active groups that are interested in helping.”

‘Re-skinning’ a coral skeleton

Though it may sound macabre, the calcium carbonate skeletons of dead reefs can serve as vital scaffolding for new corals to flourish. “Re-skinning” a dead reef takes advantage of coral microfragments, small bits of coral polyps. Growing microfragments in the lab and then transplanting them onto reef skeletons can, in a way, bring a dead ecosystem back to life.

David Vaughan discovered the restorative potential of coral microfragments through what he calls a “eureka mistake.” Vaughan, formerly executive director of Mote and now head of the nonprofit Plant A Million Corals in Summerland Key, Fla., accidentally broke off shards of a branching coral while moving it to a new tank. Some coral polyps remained on the bottom of the tank. Vaughn assumed the tiny animals wouldn’t survive. But when he checked on them about two weeks later, he saw instead that they had quickly grown and multiplied.

Large corals grow slowly, Muller says, because they have to put a lot of energy into creating more of their calcium carbonate skeleton. If you instead affix multiple microfragments, consisting of a thin skeletal layer with a small bit of live coral tissue on top, near each other on a hard surface, they grow rapidly and fuse together. Mote scientists “hacked the biology of a lot of these slow-growing species to encourage them to put a lot of their resources into creating tissue faster,” Muller says.

Microfragments of slow-growing corals that are placed near each other on the skeleton of a dead coral will quickly grow and merge together. Coral fragments, like these pictured at Mote Marine Laboratory, can be grown in land-based nurseries.Mote Marine Laboratory

A 2018 study found that microfragments of the mountainous star coral (Orbicella faveolata) grew 10 times as much tissue over a 31-month period as the normal, larger fragments that were previously used for reef restoration. For every square centimeter of coral that was planted at the beginning of the experiment, microfragments grew an average of 3.38 square centimeters of new tissue, while larger fragments grew only 0.35 square centimeters. Ocean plantings of coral microfragments have since withstood disease, bleaching and hurricanes, and grown large enough to reproduce within several years.

“Spawning after five years,” Spadaro says, “was definitely a game changer in terms of restoration.” Re-skinning with microfragments can give you functional reef ecosystems in a fraction of the time as previous methods. Mote scientists have since shared their knowledge with others working to restore corals around the world, such as in Hawaii and the Caribbean.

Making shade

Bleaching is the dramatic outcome of great hardship; pushed to the brink by extreme stress, a strained coral belches out its symbiotic photosynthetic algae, turning stark white and losing its primary food source. Excessive heat is the most common culprit, but it’s not the only one.

Excess light can lead to bleaching, too, says Peter Butcherine, a biologist at Southern Cross University in Coffs Harbour, Australia. Too much light during photosynthesis, performed by the corals’ algae partners, leads to an abundance of toxic oxygen-containing molecules that are highly reactive and can cause cell death. Protecting corals from too much sun exposure can help prevent bleaching, but “you can’t roll out thousands of square meters of shade cloth” to shield an area the size of the Great Barrier Reef, Butcherine says.

Instead, Butcherine and others have turned to a more ephemeral approach: creating fog. “It’s essentially a sea mist,” Butcherine says. Though misting the entire Great Barrier Reef isn’t feasible, marine fog could be used to protect sensitive parts of the reef during the time of day when sunlight is at its harshest.

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Too much sunlight can lead to coral bleaching, much like excessive heat can. By creating artificial marine fog using arrays of misters mounted to ships, like what’s seen in this video, researchers hope to shield reefs such as Australia’s Great Barrier Reef from harmful rays.

Butcherine and colleagues showed that shading corals for just four hours a day can delay bleaching even when water temperatures are high, such that corals could withstand three extra weeks of bleaching-level heat. The results of that laboratory study were published in the Sept. 20 Frontiers in Marine Science. This delay could help corals hold on to their algal partners until the environment around them cools.

Because it’s still being developed, marine fogging is quite expensive; it requires large arrays of misters mounted to ships. But Butcherine is excited by the potential of using solar power, including sun-powered drones mounted with misters, to implement the technique at a wider scale, and even at other reefs around the world.

 “I’m optimistic that we can make a difference,” Butcherine says. More

Saima Iqbal is the fall 2023 science writing intern at Science News. She holds a bachelor’s degree from Harvard College, where she studied the history of medicine, conducted research on cancer immunotherapies, and fell in love with narrative science writing. More