Oyster Herpes: Latest Symptom of Global Warming?

Don't worry—oysterherpes isn't a new side effect of eating"the food of love."

The incurable, deadly virus is, however, alarming fishing communities inEurope, where oyster herpes seems to be spreading—and could go on spreading as seas continue to warm, experts say.

(Also see"Fish-killing Virus Spreads to Lake Superior.")

In July lab testing of farmed oysters detected the first knownUnited Kingdomcases of herpes in the shellfish. The virus has already killed between 20 to 100 percent of breeding Pacific oysters in some French beds in 2008, 2009, and 2010, according to theFrench Research Institute for Exploitation of the Sea(Ifremer).

The reason for oyster herpes's emergence in Pacific oysters off England remains a mystery, thoughglobal warmingmay have played a part, experts speculate.

A new strain namedOstreid herpesvirus 1 (OsHV-1)μvar (mew-var),the virus remains dormant until water temperatures exceed 16 C {61 degrees F}, which U.K. waters reach in the height of summer, according to Kevin Denham of the British government'sFish Health Inspectorate.

With that in mind, Tristan Renault, director of Ifremer's genetic and pathology lab, said that global warming"could be an explanation of the appearance of this particular type of the virus."

Though all herpes strains are DNA-based viruses, herpes, which infects everything from cows to clams to monkeys, comes in a wide variety of species, each with their own unique set of symptoms. Among humans, perhaps the best known forms are theHerpes simplexviruses, which are spread through close contact and can manifest themselves as oral and genital blisters.

Ostreidherpes viruses are known to affect not only oysters but also clams, scallops, and other mollusks, according to Renault.

The New Oyster Herpes

Herpes-infected shellfish aren't new to science, but in 2008—the first year a huge increase in mortality rates was detected inFrance—Ifremer detected a new variation of the virus.

Like the other strains of herpes that affect mollusks,OsHV-1μvarattacks young oysters during breeding season, when the mollusks' bodies are so focused on producing sperm and eggs that the oysters have no energy to maintain an immune system, Renault said.

ButOsHV-1μvaris"more virulent than strains we identified before,"Renault said, adding that the virus is so efficient at killing its hosts that it can wipe out 80 percent of the oysters in a bed within a week.

That death rate is the only outward sign something's wrong, he added, because a oyster herpes have no visible symptoms, and diagnosis is possible only through lab testing.

(Related:"New, Fast-Evolving Rabies Virus Found—And Spreading.")

Oyster Herpes Appears in Britain

Though oyster herpes can't be transmitted to humans, it does threaten the fishing industry, since dead oysters are unsafe for eating—and that's exactly what worries oyster harvesters such asSeasalter Shellfish.

Based in the southeastern English city of Whitstable, where oysters have been harvested for centuries, Seasalter this summer became the first company to discover the herpes-ravaged oysters in the U.K.

The finding prompted an investigation by the Fish Health Inspectorate, which detected the virus and learned that Seasalter had employed equipment previously used in France to refurbish oyster beds.

"We were told it had been out of the water for a number of years,"Denham said."Nevertheless there's still a possibility"that the virus could have traveled from infected French beds via the gear. Possible culprits also include other reused equipment or water transferred from an infected area.

(Related:"Global Warming 'Undeniable,' U.S. Government Report Says.")

Could Oyster Herpes Spread?

To keep the U.K. oyster-herpes outbreak from spreading, the British government has banned the shipping of oysters out of affected areas, most of which, like Whitstable, are around the mouth of the River Thames in southeastern England.

No matter what measures are taken, Denham said, oyster herpes is going to be tough to kick. Even if all the infected Pacific oysters are removed from oyster farms, wild Pacific oysters will still be present in surrounding waters, perhaps acting as"a reservoir for infection."

It's unlikely, though, thatOsHV-1μvarwould end up inU.S.oyster beds, Renault said, because the United States doesn't typically import oysters from Europe.

But a less virulent, herpes-like virus has been detected in farmed oysters offCalifornia. If sea temperatures continue to rise, he said, perhapsμvaror something like it could emerge in U.S. waters too.

forNational Geographic News

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Fossil"Cat Crocodile" Had Mammal-like Teeth

Some dinosaurs, a new study suggests, knew very different crocs from today's reptiles—including a newfound fossil crocodile that might seem to have been designed by committee. (Seepictures of the prehistoric"cat crocodile.")

According to the study, the cat-sizePakasuchus kapilimaihad relatively long legs and a nose similar to adog's. Perhaps weirdest of all,Pakasuchus—literally,"cat crocodile"—hadmammal-like teeth that gave the crocodile a power previously unknown amongreptiles: the ability to chew.

As a result, the 105-million-year-old crocodile, researchers say, was something of a stand-in for mammals in the mammal-poor, long-gone southern supercontinent of Gondwana, which included thePakasuchusfossil site in what's nowTanzania.

According to lead study authorPatrick O'Connor,Pakasuchus's"legs were longer and more slender than what you think of for modern crocodiles ... and it had a little more of an upright stance,"the Ohio University paleontologist said.

Living among dinosaurs, the fossil crocodile—technically a crocodyliform—was also lankier and had fewer of the bony plates that armor modern crocodiles.

And unlike inmodern crocodiles—which have nostrils positioned on the tops of their heads, for breathing while swimming—the nose ofPakasuchuswas located at the tip of its snout, canine style.

"It was not like the crocodiles we know today, which are submerged much of the time. It was up, moving around on the land,"said O'Connor, who received aNational Geographic Society/Waitt Grantfor this project. (The Society owns National Geographic News.)

Video: Mammal-like Crocodile Found

 

(Related:"Strange Croc Pictures: New Dino-Eater, Galloper, More.")

Mammal-like Teeth Gave Crocodile Chewing Power

Modern crocodiles have fairly undifferentiated, conical teeth specialized for a bite-and-gulp feeding style. ButPakasuchushad teeth resembling mammals' canines, premolars, and interlocking molars, says the study, to be published in tomorrow's issue of the journalNature.

In addition, the lower jaw ofPakasuchuscould slide back and forth."Crocodiles alive today don't have a major sliding component to their jaw,"O'Connor explained."It's just a hinged joint that allows the jaw to move up and down."

(See"In Crocodile Evolution, the Bite Came Before the Body.")

Taken together, the crocodile's unique dentition and sliding jaw suggestPakasuchuswas able to chew and grind its food, a trait previously thought to be unique to mammals.

"Chewing is a mammalian characteristic, almost by definition,"O'Connor said.

"Most people who do functional anatomy or paleontology reserve the term for mammals only,"he said. Other animal groups are generally thought to lack the necessary anatomical features and coordinated muscle activity required for complex chewing, he added.

Pakasuchuswas almost certainly capable of chewing, agreedZhe-Xi Luo, a paleontologist and early-mammal expert at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.

"We used to think that it was not possible for crocodiles to really chew their food,"said Luo, who was not involved in the research."But {this study} shows that, yes, they could."

Crocodile Was Mammal Proxy in Land of Reptiles?

Pakasuchuslikely fed on small lizards, insects, and the few primitive mammals that existed in Gondwana at the time. The animal's unique dentition may have allowed the fossil crocodile to occupy ecological niches filled by mammals in other parts of the world, the study says.

"This small-bodied animal occupied a dramatically different feeding niche than do modern crocodilians"study co-author Nancy Stevens, also of Ohio University, said in a statement. The crocodilian order includes crocodiles, alligators, caimans, gavials, and related extinct forms.

Pakasuchusbelonged to a reptile family calledthe notosuchians, or"southern crocodiles."For this group, differentiated teeth may have been the key to success, said Steve Salisbury, a paleontologist at theUniversity of Queenslandin Australia.

Increasingly, fossil discoveries in former areas of Gondwana are revealing that the notosuchians boasted a very diverse range of species, said Salisbury, who also did not participate in thePakasuchus-fossil research.

(Also see"Armadillo-like Crocodile Fossil Found in Brazil.")

If it turns out that mammal-like teeth were typical among other notosuchians,"it may have opened up new opportunities that weren't possible with more simplified dentition,"he added.

Salisbury adds that the discovery ofPakasuchuswill likely prompt many scientists to go back and reexamine their fossil collections.

"Isolated teeth that people previously assumed belonged to mammals,"he said,"may in fact belong to crocodiles."

forNational Geographic News

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Pictures: Ancient"Cat Crocodile" Discovered

The newfound, cat-size crocodilePakasuchus kapilimai(illustrated) hadmammal-like teeth that helped give the fossil crocodile a power previously unknown amongreptiles: the ability to chew.

One key to that ability is that the 105-million-year-old crocodile's lower jaw could slide back and forth (inset).

"Crocodiles alive today don't have a major sliding component to their jaw,"said lead study authorPatrick O'Connor, an Ohio University paleontologist."It's just a hinged joint that allows the jaw to move up and down."

(Read the full story of the mammal-like crocodile.)

—with reporting by Ker Than

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Dogs'Brains Reorganized by Breeding

For thousands of years humans have changed the sizes, shapes, colors, and coats ofdogsthrough selective breeding. Now it seems we've actually reordered many breeds' brains in the process

(Seedog-evolution pictures.)

A new brain-imaging study examined 11 carcasses from 11 different dog breeds, both long-snouted, such as the greyhound and Jack Russel terrier, and short-snouted, such as the mastiff and pug.

The team found that the brains of many short-snouted breeds have rotated forward by as much as 15 degrees.

Furthermore, in these breeds the brain region for smell, called the olfactory bulb, has drifted downward toward the base of the skull, perhaps significantly altering the dogs' all-important source of smell, researchers say.

Since the first wolf was domesticated an estimated 12,000 years ago,"selective breeding has produced a lot of {anatomical} variation, but probably the most dramatic is in terms of skull shape,"said study co-authorMichael Valenzuela, a neuroscientist at the University of New South Wales in Australia.

(See"Dog First Tamed in China—To Be Food?")

"Dogs are very unique in having such a massive diversity of skull shapes,"Valenzuela added,"more than any other species really."

Dog Brain Changes Equal Changed Behavior?

It's unclear whether the brain rotation and olfactory bulb movement of short-snouted, or brachycephalic, dogs has affected their ability to smell, but Valenzuela and his colleagues note that short-snouted dogs are usually not used for scent work.

"We think of dogs living in a world of smell—but this finding strongly suggests that one dog's world of smell may be very different to another's,"study co-author Paul McGreevy of the University of Sydney said in a statement.

(See National Geographic fans'dog pictures.)

One way the brain changes could have changed the dogs' olfactory sense is by affecting a pathway in the brain called the rostral migratory stream, or RMS, the team speculates. Other studies have suggested the RMS is important for a normal sense of smell.

"The RMS starts very deep in the middle of the brain and traces a very predictable path to the olfactory bulb,"study co-author Valenzuela told National Geographic News.

"Since the olfactory bulb has moved in brachycephalic dogs, you'd expect to see a change in the course of the RMS, or it may be disregulated"and dysfunctional, he added.

Investigating these potential RMS deviations, the authors write, would"be of intense interest for future research."

Valenzuela's team plans to undertake at least some of that future research and hope to uncover whether—or how—breeding-based brain changes have changed the sense of smell in dogs."It is a fascinating question that our group will be looking into more."

For more on dog evolution, watch And Man Created Dog on the National Geographic Channel, Sunday at 9 p.m. ET/PT>>

The research is detailed in the online journalPLoS One.

forNational Geographic News

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Photos: Dragonfish, Fireworm, More Found by Sea Surveys

Australia's"terrifying"dragonfish (pictured) uses its many fangs—which even stud its tongue—to hook hard-to-find prey in the cold, dark depths, scientists say.

The banana-size fish is one of tens of thousands of both known and new species included in a new inventory released today by theCensus of Marine Life, a decade-longocean-exploration project.

(Seea video of creatures included in the record-breaking survey.)

The first-of-its-kind"roll call"of marine species from 25 diverse ocean regions is a prelude to the census's final summary of up to 230,000 species to be released October 4, census scientists say.

(MoreCensus of Marine Life pictures:"Hard-to-See Sea Creatures Revealed.")

To create the inventory—published Monday in the journalPloS One—scientists combined years of census data with previous research on the richness of ocean species. Species counts in each of the 25 areas ranged from 2,600 to 33,000, with an average of about 10,750 per region. Altogether census scientists found more than a hundred thousand species in the 25 regions.

"This inventory was urgently needed for two reasons,"report lead authorMark Costello, of the Leigh Marine Laboratory at New Zealand's University of Auckland, said in a statement.

First, not knowing what species ply the oceans"impairs society's ability to discover and describe new species,"Costello said.

The research may also serve as a base line, helping scientists to track future extinctions:"Marine species have suffered major declines—in some cases 90 percent losses—due to human activities and may be heading for extinction—as happened to many species on land."

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Photos:"Spectacular" Deep-Sea Species Found off Canada

An unidentified purple octopus (pictured) is one of 11 potentially new species found this month during a deep-sea expedition off Canada's Atlantic coast, scientists say.

(Relatedpictures:"Surprising Creatures Found Deep off Australia.")

Still at sea, a team of Canadian and Spanish researchers is using a remotely operated vehicle calledROPOSfor dives offNewfoundlandwith a maximum depth of about 9,800 feet (3,000 meters).

The 20-day expedition aims to uncover relationships between cold-watercoraland other bottom-dwelling creatures in a pristine yet"alien"environment, according to theresearchers' blog.

"It's been really spectacular,"Ellen Kenchington, research scientist with the Fisheries Department of Canada—one of the organizations involved in the project—told Canada'sCTV Newswebsite.

"It's really changing our perception of the diversity that's out there. ... We're seeing new species in deeper waters."

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Alligator"Feeding Frenzy" Video Shows Teamwork

On a July 10 fishing trip inGeorgianreaches of the Okefenokee Swamp, Ray Cason found his way blocked by what looked to him like analligatorfeeding frenzy.

Hundreds of alligators packed a roughly 30-foot-wide (9-meter-wide) stretch of canal, jumping over and snapping at each other—all of it caught on a video (watch below) that went viral Wednesday viaYouTube,Facebook,CNN, and other media.

Alligator"Feeding Frenzy"Video

 

"I ain't never seen so many gators in my life!"someone can be heard exclaiming in the video, which Cason, 39, posted on YouTube after his foray into 420,000-acre (170,000-hectare)Stephen C. Foster State Parkoutside the town of Fargo.

Georgia state wildlife biologist Greg Nelms agreed, telling CNN,"I've never seen footage like that before."Such"cooperative feeding"by alligators—a true feeding frenzy is more chaotic—is seen every three or four years in the area, Nelms added.

In general, though, it's not uncommon forAmerican alligators, which can grow to about 15 feet (4.6 meters) long, to engage in cooperative feeding, herpetologistKenneth Kryskotold National Geographic News.

"There could be multiple reasons"for the swarm seen in the viral video, said Krysko, of the University of Florida."But they're usually known to congregate when they're breeding as well as when they're feeding."

Since American alligators breed in spring and the"feeding frenzy"video was shot in July, predation is the most likely reason for the Okefenokee gator swarm.

(Pictures: Giant Rays' 'Feeding Frenzy' Spots Protected.)

Don't Call It An Alligator Feeding Frenzy

An alligator feeding frenzy tends to occur when the reptiles, fishing in evaporating pools or captive enclosures, engage in a violent free-for-all. The gators clash violently over food and block smaller rivals from feeding,according to the University of Floridawebsite.

Cooperative feeding, by contrast, is pretty much what it sounds like.

Alligators"face into the current and arrange themselves side-by-side in a row across the flow of water"—the better to catch a flood of fish squeezed into a bottleneck in a free-flowing channel, the university site says.

That's apparently just what happened in the Stephen C. Foster State Park canal in the video, where mudfish, or bowfins—common prey for Okefenokee alligators—are said to have been particularly plentiful on July 10.

Other hallmarks of cooperative feeding by alligators: Fighting over prey is relatively rare, and the feeding is so intense that humans and other interlopers are often ignored.

Low water can make alligator congregations more likely too, by forcing fish to stream, en masse, toward deeper water, Krysko said.

(Relatedvideo: Humpback Whales' Feeding Frenzy.)

Easing Through the Alligators

In the alligator"feeding frenzy"video, alligators can be seen jumping over one another and attacking each other, presumably while competing for food. Cason estimated there were about 300 alligators gathered.

There was"a lot of noise and a lot of splashing,"Cason told local television news station News4Jax.

"I just eased through them and went fishing"—perhaps not the wisest decision, according to the University of Florida's Krysko.

(See a picture of apython that burst after having eaten an alligatorin Florida.)

Though Krysko said the alligators were probably not abnormally dangerous during the congregation, he said Cason put himself in danger of falling into the congregation—and risked harming the alligators with his boat.

American alligators"are a protected species,"said Kysko, referring to protections afforded by the U.S. Endangered Species Act, even though the species is no longer listed as endangered by the U.S. government."No one would be allowed to do that if they were manatees, and manatees are protected as well."

Blair Hayman, a biologist withFlorida'sAlligator Management Program, though, didn't see anything wrong with the fisher motoring through the alligator swarm.

"It doesn't appear that he is doing anything,"she said."He's just boating at normal speed. Typically {alligator} harassment would be if he were poking {an alligator} with a stick or intentionally touching or otherwise disturbing him."

(More video: how to tell alligators from crocodiles.)

It's not illegal for fishers to be near alligators, she added, and sometimes it's downright unavoidable.

More:"Human-Alligator Encounters Rising in U.S. Southeast">>

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