October 3, 2012
A little over two years ago, marine researchers set sail aboard the French schooner Tara as part of a plan to create the first comprehensive global picture of plankton ecosystems. By the time the journey concluded earlier this year, they had observed roughly 1 million previously unidentified species of plankton, giving an unprecedented window into the diversity of marine life at the most basic level of the food chain.
Unfortunately, the group’s findings weren’t all rosy. If, as they note, “studying plankton is like taking the pulse of our planet,” then Tara‘s journey also included the discovery of something like an irregular heartbeat. Last week, the researchers revealed that while collecting samples in the Southern Ocean (the waters that encircle Antarctica), they detected remarkably high levels of plastic pollutants in a habitat that was widely considered to be unspoiled.
“We had always assumed that this was a pristine environment, very little touched by human beings,” Chris Bowler, one of the team’s scientists, told The Guardian. ”The fact that we found these plastics is a sign that the reach of human beings is truly planetary in scale.”
The researchers expected to find some level of plastic in the waters, as all of the world’s oceans contain pieces of plastic debris—most are microscopic particles that result from the degradation of objects like plastic bags and bottles. But the team’s samples, collected from four different locations in the Southern Ocean and Antarctica, revealed concentrations of plastic far higher than they would have predicted: roughly 50,000 fragments per square kilometer, a figure that was considered a “high” amount just a couple of years ago but is now simply the world average for oceanic plastic concentration. The group says that they had expected to find concentrations of plastic somewhere around 5,000 fragments per square kilometer in the remote waters near Antarctica.
Although the Great Pacific Garbage Patch is the most notorious area of concentrated waste debris in the ocean, the North Atlantic and North Sea are also home to high amounts of floating plastic and garbage. What makes the discovery of such debris near Antarctica such a concern is that, unlike these areas near Europe and Asia, the Southern Ocean is distant from most human activity, indicating just how far this type of pollution has spread over time.
“Discovering plastic at these very high levels was completely unexpected because the Southern Ocean is relatively separated from the world’s other oceans and does not normally mix with them,” Bowler said. It’s difficult to know exactly where the plastic in these waters originated, but based on ocean currents, the Tara researchers speculate that the majority came from Australia, Africa and South America.
Floating plastic debris harms wildlife in a number of ways. For birds and fish, larger pieces are mistaken for food, and consumption of enough plastic can be toxic. On the Midway Islands, nearby the Great Pacific Patch, researchers have determined that all 2 million resident Laysan albatrosses have some quantity of plastic in their stomach, and that about a third of albatross chicks die due to being mistakenly fed plastic by their parents.
On a smaller level, UV light and the salt in seawater cause microscopic particles of plastic to emit toxic chemicals such as PCBs and DDT. When ingested by many types of marine species, these can be mistaken for estradiol, a sex hormone, causing a variety of symptoms related to endocrine disruption. Additionally, the chemicals tend to bioaccumulate in organisms as they move up the food chain, and can eventually lead to tainted populations of fish that humans regularly consume.
These sorts of problems have led Charles Moore, an oceanographer and racing boat captain who played a significant role in discovering and publicizing the great Pacific Garbage Patch, to argue that plastic pollution has become a more urgent problem for ocean life than climate change. “The sad thing is we thought Antarctic waters were clean,” he told the Australian Associated Press after the Tara‘s findings were announced. ”We no longer have an ocean anywhere that is free of pollution.”
September 19, 2012
In our October issue, Michelle Nijhuis joins wildlife biologists in searching Colorado’s caves and waterfalls for one of the world’s most mysterious bird species: the black swift. Although fewer than 100 breeding sites of the black swift are known, Nijhuis was lucky enough to see ornithologist Ron Torretta locate a black swift that had been geotagged in 2010, providing researchers with a cache of information about the wanderings of the enigmatic bird. Here are a few more of the most mysterious and elusive of the world’s bird species.
1. Night Parrot: Between 1912 and 1979, birders spotted this elusive species, native to the interior of Australia, exactly zero times—leading most scientists to believe it had gone extinct. Since then, a tiny handful of sightings of the nocturnal, yellow-green bird have occurred, and experts now estimate that the population is somewhere between 50 and 250 mature individuals. After the last verified sighting in November 2006, when park rangers in the state of Queensland turned up a decapitated specimen that had died after flying into a barbed-wire fence, the Australian government chose to keep the find temporarily secret while they searched for more night parrots, so as to avoid an influx of birders flooding the remote park in hopes of spotting one of the world’s rarest birds.
2. Ribbon-tailed Astrapia: Endemic to the forest highlands of Papua New Guinea, this bird has the longest tail feathers (in relation to body size) of any bird species, with feathers three times its body length. Unfortunately, this stunning plumage has enticed poachers; hunting, along with habitat loss, has led to the species being listed as “near threatened” by the International Union for Conservation of Nature. The species, the most recent bird of paradise to be documented, was first described by explorer Fred Shaw Mayer in 1938.
3. Palila: This species of Hawaiian honeycreeper has one particularly mysterious characteristic—it subsists almost exclusively on the seeds of the māmane plant, which contain a level of toxins that would kill any other small animal. Scientists aren’t sure how the birds digest the seemingly-lethal seeds, although the palila have been observed avoiding certain plants, indicating they might have a way of selecting seeds with lower levels of poison. In 1978, the federal government ruled that feral goats and sheep had to be removed from the palila’s only remaining habitat—the upper slopes of Mauna Kea on the Big Island of Hawai’i—since they consumed māmane plants and threatened the birds’ survival.
4. The Kakapo: Some 82 million years ago, the island of New Zealand broke off from what would become Australia, and the strange, flightless nocturnal parrot species called the kakapo began its unusual evolutionary path. In the absence of predators, it became the world’s largest type of parrot and lost the ability to fly; when European colonists introduced cats, rats and ferrets to New Zealand to control the population of rabbits, the kakapo was nearly wiped out. Now, just 126 wild kakapos live on three predator-free islands off the coast of New Zealand.
5. The Crested Ibis: Named for the crest of white plumage that extends from its nape, the crested ibis used to nest across Japan, China, Korea, Taiwan and Russia. By 1981, after years of habitat loss, just five individuals remained in the wild in Japan, and though scientists took the birds into captivity, a breeding program was unsuccessful. Now, the last remaining wild population—some 500 birds in the Chinese province of Shaanxi—is being buttressed by chicks hatched in captivity as part of a Chinese program. Although the species is still listed as endangered, scientists are cautiously optimistic that it is finally making a comeback.
August 20, 2012
Two years ago, the explosion and subsequent oil spill from the Deepwater Horizon well in the Gulf of Mexico put oil dispersants in the news. In order to protect the Gulf coastline and minimize damage to oceanic ecosystems, dispersant chemicals were sprayed at the source of the leak—as well as on the floating sheet of oil on the water’s surface—to break up and dilute the harmful substance.
Many questioned the safety of the dispersants, however, and several of the ingredients in the chemicals deployed were shown to be toxic. Additionally, some scientists have argued that spreading oil throughout the water column, instead of leaving it concentrated on the surface, does more harm than good.
“The use of a traditional dispersant really comes down to the lesser of two evils,” says Lisa Kemp, a University of Southern Mississippi researcher who works on developing next-generation oil dispersant technologies. “Even if you have the safest possible dispersant, the components of the oil are toxic. So do you leave the oil on the surface of the water, where birds and other aquatic animals can be exposed to it, or do you add this dispersant to break the oil into small drops and send it through the water?”
Someday soon, though, oil spill cleanup coordinators might not have to make this type of difficult decision. Research by Kemp and her colleagues is yielding dispersants that are entirely harmless—and, intriguingly, are actually made from ingredients found in some familiar foods. ”Each of the ingredients in our dispersant is used in common food products like peanut butter, chocolate and whipped cream,” says Kemp, describing research she is presenting today at the American Chemical Society national meeting in Philadelphia. ”Other scientists are working on new oil dispersants and absorbents but nothing that’s quite like ours.”
Her research team’s new dispersant has another huge advantage over traditional dispersants: It’s extremely buoyant. The conventional approach is to break up an oil slick into tiny droplets that sink underneath the surface, so they improve the cosmetic appearance of the spill, but that puts new portions of the local ecosystem at risk. The new type of dispersant breaks up the slick into droplets that stay afloat, so they are made more available for oceanic microbes to digest and can also be more easily cleaned up by mechanical means such as boats with skimmers and absorbent booms.
Additionally, the new dispersant includes special non-stick polymers, so it is more effective than conventional formulas at protecting wildlife in the event of a spill. “It not only breaks up oil but prevents the deposition of oil on birds and other objects,” she explains. “Birds can sit in slicks of the dispersed oil, they can dive through it and take off and flap their wings, and the oil will fall off.”
Normally, removing oil from birds after a spill requires the use of detergents, which can remove their feathers’ natural waterproof coating. This leaves them less buoyant and more at risk of contracting hypothermia. Left to their own devices, birds often try to eat the oil on their feathers, leading to internal damage. The fact that the new dispersant prevents oil from sticking could be a huge boon for seabirds.
In order to develop the innovative dispersant, Kemp and her colleague, Robert Lochhead, looked to decades-old concepts from an unlikely source: the laundry detergent industry. Their polymer that coats the oil droplets and prevents them from sticking to birds, for instance, is inspired by a common ingredient in laundry detergent that prevents oil removed from a piece of clothing from getting re-depositing on other items in the wash. “Detergents include anti-redeposition agents that stick to oil and grease droplets removed by washing and keep them suspended in the water,” Kemp says.
After successfully testing their dispersant in the lab, Kemp and her team are looking to proceed to field trials of the substance on a larger scale. Although no one wants to see another maritime significant maritime oil spill, if the new dispersant proves successful, we may at least have a safer option for cleaning it up.
August 8, 2012
When we think about the smartest animals, chimpanzees are usually the first to come to mind. Experiments show that they can memorize sequences of numbers, learn the meaning of words and associate particular voices with specific faces. Crucially, previous studies have found that chimps and other apes are the only non-human animals capable of making abstract logical inferences based on cues from their environment.
A new experiment, though, might make us recognize that an entirely different species belongs in this exclusive group: the African grey parrot.
In several previous experiments, researchers claimed they’d revealed the ability of parrots to make inferences based on their skill in completing an extremely simple task. The animals were shown a pair of closed canisters, one with food inside and one empty, and the top of the empty one was briefly opened. Afterward, when they were given the chance to choose one or the other, they reliably selected the one with food. Critics, though, said that this didn’t necessarily demonstrate any sort of inferential reasoning—they could simply be avoiding the empty canister, rather than realizing its emptiness implied there was food in the other.
In the new study, however, published yesterday in the Proceedings of the Royal Society B, researchers from the University of Vienna gave six grey parrots a slightly more complex task. Instead of being shown an empty and a full canister, the researchers merely shook one of the containers, so the parrots could hear either the sound of walnuts rattling around inside or silence.
When given the chance to select a canister, the parrots consistently chose the one with the walnuts, whether they had heard the shaking of either container. They were able, therefore, to determine both that a noisy shaking meant “food is inside” and that a noiseless shaking meant “no food is inside, so it must be in the other one.”
To confirm that the parrots were actually making inferences about the location of food, and not merely avoiding a silent box, the researchers introduced one more variation to the task. Instead of using the actual canisters to make the noises, they wore small speakers on their wrists that emitted shaking noises. In some cases, they shook the box in their right hand, but emitted the shaking noises from a speaker on their left wrist; in other cases, they played the sounds from the correct side. The parrots only made the right selection on a consistent basis when the sound lined up with the shaking—so they were making an inference not based on a visual or aural cue alone, but from noting the connection between both.
Although this might not seem that impressive, no other non-primate species has been able to successfully complete this type of task, and humans are not typically able to do this until they reach three years of age. The fact that the parrots were able to make these sorts of judgements based on sounds associated with food—and visuals that would logically produce the sounds—confirms that they are indeed capable of abstract, inferential reasoning. ”It suggests that grey parrots have some understanding of causality and that they can use this to reason about the world,” lead author Christian Schloegl told LiveScience.
Most interesting, from an evolutionary perspective, is the fact that parrots are not close relatives of primates, so their ability to reason presumably evolved separately. ”The most important point is that higher intelligence is nothing that evolved only once,” Schloegl said. “Comparable cognitive skills evolved several times in parallel in only distantly related species such as primates and birds.”
December 30, 2011
On January 1st of this year, we awoke to reports of thousands of birds dead in Arkansas. The cause was not immediately known, and some people started to freak out, even saying that the event was a sign of the coming apocalypse.
Of course, within days scientists had an answer–the birds were likely startled by fireworks and, unable to see in the night, they ran into houses and signs and other objects and died from the trauma.
It turns out that birds are easily startled by fireworks. A study in the November/December issue of Behavioral Ecology used weather radar to track birds disturbed by New Year’s Eve fireworks for three years in the Netherlands. They found that thousands of birds took to the skies shortly after midnight and didn’t settle down again until 45 minutes later.
The scientists estimated that hundreds of thousands of birds, including several species of migratory waterfowl, were disturbed by the fireworks each year in the Netherlands alone. “The unexpected loud noises and bright lights fireworks produce are probably a source of disturbance for many species of domestic and wild animals,” the scientists wrote.
Most of the time, birds won’t die from the fireworks displays, as they did in Arkansas, the researchers note. But they still suffer from disrupted sleep, interrupted feeding and the energetic costs of flight and resettlement.
So, if you wake up on Sunday morning to more reports of dead birds, don’t think it’s Armageddon, but have a thought for the effects of our pretty displays on the wildlife around us.