Category: Environment

Since pythons invaded, Florida’s mammal populations have crashed

By Ed Yong | January 30, 2012 3:00 pm

It turns out that if you unleash giant snakes into a place that didn’t previously have giant snakes, the other local animals don’t fare so well. That seems obvious, but you might be surprised at just how badly those other animals fare.

Since 2000, Burmese pythons have been staging an increasingly successful invasion of Florida. No one knows exactly how they got there. They normally live in south-east Asia and were probably carried over by exotic wildlife traders. Once in America, they could have escaped from pet stores or shipping warehouses. Alternatively, overambitious pet owners could have released when they got too large for comfort. Either way, they seem to be thriving.

With an average length of 12 feet (4 metres), the pythons are formidable predators. They suffocate their prey with powerful coils, and they target a wide variety of mammals and birds. The endangered Key Largo woodrat and wood stork are on their menu. So are American alligators (remember this oft-emailed photo?). Conservationists are trying to halt the spread of the giant snakes, out of concern that their booming numbers could spell trouble for local wildlife.

Michael Dorcas from Davidson College thinks they are right to be concerned. In the first systematic assessment of the pythons’ impact, Dorcas has found that many of Florida’s mammals have plummeted in numbers in places where the snakes now live.

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Fire ants conquered America by monopolising calorie-rich food

By Ed Yong | December 5, 2011 3:00 pm

They came to America and found a nation overflowing with calories. Carbohydrate-rich fast food was available on every corner, and with little competition for it, the migrants ate their fill. Soon, they started spreading throughout this new land of opportunity. They are red imported fire ants (Solenopsis invicta) and their invasion is well underway.

The fire ant is an international pest. It devastates native ants, shorts out electrical equipment, damages crops, and inflicts painful stings. It hails from Argentina, but it was carried to the United States aboard cargo ships that docked at a port in Alabama. That was in the 1930s; since then, this invader has spread throughout the southern states, from California to Florida. The country spends over a billion dollars every year in attempts to stem the invasion.

Now, Shawn Wilder from Texas A&M University has found that their remarkable invasion has been driven by partnerships with local insects. The fire ants run a protection racket for aphids and other bugs, defending them from other attackers. In return, they get honeydew, a sweet nutritious liquid that the bugs excrete, after they suck the juices of plants. They are both farmers and bodyguards.

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Disease from human sewage is killing Caribbean corals

By Ed Yong | August 23, 2011 9:00 am

Forty years ago, the elkhorn coral was one of the most common species in the Caribbean. Five years ago, it was listed as critically endangered. The coral’s woes are many but, aside from the warming temperatures, predators and storms that affect all corals, the elkhorn is also plagued by a highly contagious malady called white pox disease. White lesions erupt all over the coral’s branches, representing areas where its animal tissue has wasted away to leave the white skeleton.

Now, Kathryn Patterson Sutherland from Rollins College in Florida has discovered the cause of white pox disease, and it’s an unexpected one – us. We have literally landed the elkhorn in s**t.

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Eco-labelled fish may be unsustainably fished, or the wrong species

By Ed Yong | August 22, 2011 12:00 pm

The Chilean seabass is no stranger to being mislabelled. It bears little relation to the various fish that are also known as basses, and it’s more properly referred to as the Patagonian toothfish (a name that is presumably more difficult to market). But the confusion doesn’t end there. While the toothfish is the target for illegal and unsustainable fishing operations, the Marine Stewardship Council (MSC) has certified one fishery as being sustainable. It’s found around the island of South Georgia near the tip of South America.

But some products marked as certified toothfish don’t come from this fishery. Some aren’t even toothfish at all.

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CATEGORIZED UNDER: Environment, Fishing, Genetics

The living toothbrushes that keep coral reefs healthy

By Ed Yong | June 27, 2011 2:00 pm

The most important fishes on a coral reef aren’t the impressive predatory ones or the flashy colourful ones – they’re just humble cleaners.

The cleaner fish Laborides dimidiatus is cross between a janitor and a medic. It runs special “cleaning stations”, which other fish and ocean animals visit for a regular scrub. The cleaners remove parasites from their clients, even swimming into the open jaws of predators like moray eels and groupers. They’re like living toothbrushes and scrubs. And they work hard – every day, a single cleaner inspects over two thousand clients, and some clients visit the stations more than a hundred times a day.

The cleaners, and their relationships with their clients, make a classic case study for biologists studying the evolution of cooperation. The tiny fish clearly get benefits in the form of a meal, and they enjoy a sort of diplomatic immunity from otherwise hungry hunters. On the face of it, the clients also benefit by getting scrubbed of harmful parasites. Now, Peter Waldie from the University of Queensland has shown how important this hygiene is.

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Satellite pictures reveal “landscape of fear” in Great Barrier Reef

By Ed Yong | June 14, 2011 9:00 am

From the ground, Heron Island looks like it has materialised out of a holiday brochure. It’s home to pristine beaches and lazing tourists, all surrounded by the turquoise waters of Australia’s Great Barrier Reef. But there’s an aspect to Heron Island that doesn’t fit with this idyllic vibe. It’s what Elizabeth Madin from the University of Technology, Sydney, has dubbed a “landscape of fear”. To see it, you need to take to the air.

Satellite images of Heron Island, freely available as part of Google Earth, depict the same vibrant colours. But around some of the reefs, there are distinct halos – light blue rings that encircle patches of rock and coral. These rings are caused animals such as fish and sea urchins, which munch on the algae and seaweed that cover the reef floor. These grazers hide from predators within the rocks and dart out to eat the surrounding algae, leaving behind a barren halo among an otherwise green landscape.

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CATEGORIZED UNDER: Ecology, Environment, Fishing

Jellyfish shift ocean food webs by feeding bacteria with mucus and excrement

By Ed Yong | June 6, 2011 3:00 pm

Despite its name, the Gulf of Mexico’s Dead Zone is full with life. This region stretches over 22,000 square kilometres, an area the size of Israel. Its waters are choked by a combination of fertiliser, sewage and industrial run-offs, flowing down from the businesses that line the Mississippi. These pollutants feed large blooms of algae that ultimately rob the water of oxygen, depriving it of the ability to support fish and other typical residents. Instead, the Dead Zone has become the dominion of jellyfish.

Jellyfish congregate here in their thousands. Locals like moon jellies and sea nettles are joined by foreign travellers like the Australian spotted jellyfish. These gelatinous swarms stretch for miles, covering the ocean in a web of pulsating umbrellas and stinging tentacles. At their densest, you could scoop up a hundred jellies within a single cubic metre of water. They shut down beaches, fisheries, industries and ecosystems.

The reasons for these swarms are unclear. By overfishing, we could have removed the jellies’ main competition for food. By sinking man-made debris like vehicles and rigs, we could have created habitats for their larvae. By raising the temperature of the oceans and pumping them with pollutants, we could have created warm, oxygen-poor waters that only they can thrive in.

The jellyfish blooms are a natural phenomenon but marine biologists suspect that they are becoming increasingly common. Reports are constantly flooding in of unusual thick and large swarms, not just in the Gulf of Mexico, but all over the world from the Mediterranean to the Japanese coast. The worry is that we are witnessing a transition from an ocean full of scales, shells and flippers to one that’s ruled by jelly.

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Vegetarian piranhas are the Amazon’s champion gardeners

By Ed Yong | March 22, 2011 8:00 pm

This monstrous fish is a tambaqui, a close relative of the piranha. Fortunately, it doesn’t share its cousin’s flesh-eating lifestyle. Instead, the 30-kilogram tambaqui (or pacu) is a vegetarian. It swims through the flooded forests of the Amazon, eating fruits that drop from the overhanging trees. In doing so, it acts as an vehicle for the Amazon’s seeds, carrying them to distant parts of the jungle within its gut.

This is a role that we normally associate with birds or monkeys, but Jill Anderson from Cornell University has found that the tambaqui is a champion seed carrier. It can spread seeds over several kilometres, further than almost any other fruit-eating animal on record.

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Drying out the cane toad invasion

By Ed Yong | February 22, 2011 7:00 pm

In June 1935, the cane toad began its invasion of Australia. Sailors brought the animal over from Hawaii in an attempt to control the cane beetle that was ravaging Australia’s sugar cane crops. It was a mistake that the continent’s wildlife would pay for. The toad did nothing to stop the beetles. Instead, it launched its own invasion, spreading across the continent from its north-eastern point of entry. As it marched, it left plummeting populations of native species in its wake.

The toads are born conquerors. Females can lay 35,000 eggs many times a year, and each can develop into a new frog in less than 10 weeks. They’re unfussy eaters and they’ll munch away on bird eggs, smaller native frogs and more. And they have large glands behind their heads, which secrete a milky poison. Local predators (or domestic pets) that try to eat them tend to die.

Now, Daniel Florance from the University of Sydney has found a clever way of corralling the cane toad invasion. He realised that humans have continued to give the toad a hand, long after we first brought them to Australia. By creating dams and troughs, we provided the toad with watery staging grounds that allowed it to spread across otherwise impassably dry land.

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How much would it cost to identify all the animals?

By Ed Yong | February 15, 2011 12:33 pm

Around $263 billion US dollars, if a new paper is to be believed.

I’ve wrote about the paper for Nature today and the story appears on their The Great Beyond blog. Head over there to read the full thing. Here’s an excerpt:

Based on a survey of 44 Brazilian taxonomists (representing 9% of the country’s total), the duo calculated the average cost of training, funding and equipping people in the field. This might seem like an unrepresentative sample, but Brazil contains 10% of the world’s animal species and the country’s taxonomists are among the world’s most prolific. Their salaries also come close to the global average for professors.

Carbayo and Marques found that the average researcher described 25 species in their career. With around 1.4 million known animals, and an estimated 5.4 million species to discover, the duo calculated that it would take US$263 billion to cover them all. Their figures are published in an open-access letter in Trends in Ecology and Evolution.

Not all species are equal. It costs three times as much to describe a new vertebrate than an insect, although there are almost 300 times more of the latter left to identify. “You can effectively consider the warm-blooded things as done,” says Alistair Dove, who studies fish parasites.

In the rest of the piece, Chris Laly from London’s Natural History Museum comments on how online tools could drive th costs down, and Al Dove (@para_sight) says that not all taxonomists are equal. You should also read Craig McClain’s excellent WIRED article on how the scientists who study life’s richness are themselves an endangered species.

Image by Retro traveler

CATEGORIZED UNDER: Animals, Conservation, Ecology, Environment
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