Nature Shock

Tuesday 3rd November 8.00pm

The documentary series examining freak occurrences in the natural world concludes. In 1986, a mysterious natural disaster claimed the lives of nearly 2,000 people at a lake in Cameroon. Scientists initially believed an underwater volcanic eruption was to blame, until the evidence pointed them towards an astonishing new scientific phenomenon.

On 21 August 1986, disaster struck a remote corner of north-west Cameroon. Nearly 2,000 people dropped dead by Lake Nyos without any obvious signs of injury or struggle. The following day, news of the staggering scale of the tragedy reached the outside world.

Father Anthony Bangsi, a missionary in the village of Subum, recalls the awful event. He was a witness to the aftermath of the terrifying incident that virtually wiped out an entire village. Neither Anthony nor any of the locals could explain what happened at Lake Nyos.

American lake expert George Kling was one of the first outsiders on the scene. There was some evidence to suggest that a volcanic eruption under the lake was to blame for the incident. Bodies were burnt and people recalled smelling volcanic gases like sulphur in the air. However, Kling could find no proof of lava flows, fire fountains or any traces of volcanic gases. Moreover, the temperature of the lake was actually cooler than normal. Kling concluded that a volcano could not be responsible for the tragedy. What, then, was the cause?

Officials turned to Icelandic volcanologist Haraldur Sigurdsson, who had investigated a similar incident in Cameroon two years earlier. In 1984, Sigurdsson was dispatched to the volcanic Lake Monoun to probe 37 very similar deaths. As in the disaster at Nyos, the victims died in one night without any sign of a struggle. Sigurdsson was asked to confirm that an eruption was to blame, but his tests also showed no evidence of volcanic activity.

A sample taken from the bottom of Lake Monoun provided a possible answer. The water was found to contain large amounts of carbon dioxide, a natural gas that, in sufficient quantities, can kill through suffocation. Sigurdsson formulated a hypothesis called ‘lake overturn’. He postulated that an unprecedented natural disaster could occur when a large concentration of CO2 stored in a lake erupts to the surface.

However, Sigurdsson’s theory was deemed too controversial as nothing like it had ever happened before. It was ignored by his fellow scientists, and his suggestion that other lakes in the region be checked for high levels of CO2 was rejected by the Cameroon government. This mistake led to the massive loss of life at Lake Nyos two years later.

Back at Nyos, George Kling decided that Sigurdsson’s theory could be right. His own investigation found large quantities of CO2 in the deep water of the lake. He concluded that this natural gas erupted in a toxic cloud that poisoned three lakeside villages. This cloud would have been invisible, silent and odourless, rendering it the perfect killer.

The theory was supported by the discovery that the burns on the victims’ bodies were in fact inflicted by frostbite from the cold carbon dioxide and not from hot volcanic gases. Kling also found research from the US Air Force that proved exposure to CO2 can lead to hallucinations where victims imagine they smell sulphur. These extraordinary revelations paved the way for new safeguards to prevent any repeat of the tragic accident at Lake Nyos.

Tuesday 27th October 8.00pm

The documentary series examining freak occurrences in the natural world continues. This instalment explores the mysterious deaths of a family of five elephants in a remote Indian village. While official reports concluded that the animals were killed by lightning, many experts believe that a more sinister force was to blame.

On 4 May 2007, the village of Kumargram in the Indian state of West Bengal became the focus of international attention. Shortly after dawn, a truck driver made a remarkable discovery – five elephants lay dead in the dry bed of the Raidak River. Rumours of the spectacle spread fast, such that a crowd had gathered by the time officials from the Forest Department arrived on the scene. “At first I did not believe it,” recalls deputy field director Subhankar Sengupta. For India’s many Hindus, the elephant is sacred, so the death of a whole family of the animals was a tragedy. “It felt unreal,” recalls one onlooker. “It was the worst incident I have ever witnessed.”

As villagers laid flowers and said prayers, Sengupta and his team began the investigation into how the elephants had died. With no obvious evidence of disease and no power lines nearby – a relatively common cause of elephant death – the team looked towards the weather. It came to light that there was a fierce electrical storm on the previous night, leading Sengupta to theorise that a lightning strike killed the animals where they stood. “At one look you could see that their death was instant,” he says. “Those animals simply dropped dead.”

However, some found this conclusion hard to believe. Could lightning really have killed so many elephants in just one strike? While the Forest Department considered the case closed, a sinister theory began to emerge – that the elephants had been deliberately poisoned. Despite the animal’s revered status, there have been many of cases of elephant poisoning in West Bengal – though never on this scale. Deforestation coupled with the everincreasing human population means that elephants and people often come into conflict over land.

Journalist Subir Bhaumik has been documenting the changing relationship between humans and elephants in India for 20 years. He thinks that the Forest Department had an ulterior motive in reaching the lightning conclusion. In the event of poisoning being ruled the cause of death, the state would come under intense public scrutiny, a criminal investigation would be launched and there would be an uproar amongst the country’s media. “You’ll find very often they ignore poisoning,” says Bhaumik.

Christy Williams of the WWF, meanwhile, is convinced that the pattern of faeces in the riverbed means that the animals were not killed instantly – rather that they were in the area for some time before they died. He attributes their tight grouping at death not to a sudden strike, but to the animals’ strong social bonds that mean as soon as one of their number falls, the rest stop to help. “I think the whole group was poisoned,” says Williams.

The only way to prove the cause of death was to conduct a necropsy. On the day of the discovery, vets arrived to dissect the animals and remove their organs for testing. It was not until four months later that the toxicology reports were complete. To the surprise of many experts, all the tests came back negative for poison, suggesting that the elephants had indeed been killed by lightning. But why was there no sign of burning on the animals’ skin? Why was death not instantaneous? And how were so many killed in one go?

Forensic pathologist Ryan Blumenthal thinks he has the answer to these questions. Based on studies of similar cases in South Africa, Blumenthal believes that the lightning did not strike the animals directly. Instead, the animals were killed when lightning struck the ground nearby and entered their bodies via a process called ‘step potential’. Owing to the dispersal of current across the earth, the elephants would have died at different stages. Blumenthal also dismisses the lack of burning on the animals’ skin. “Lightning does not cause charring of the body,” he says. “It takes too short a time period.” For the Forest Department, this new evidence vindicated its conclusion, but some experts remain unconvinced to this day.

Tuesday 20th October 8.00pm

The documentary series examining freak occurrences in the natural world continues. This instalment explores a spate of hippo deaths on a nature reserve in Uganda. Tests confirmed that the hippos were dying from anthrax, possibly contracted from infected soil. However, the unusual nature of the outbreak gave rise to a second, even more shocking theory – that the anthrax was being spread among the hippos through cannibalisation.

In August 2004, the Queen Elizabeth National Park in Uganda was confronted with a most disturbing mystery. After a long spell of dry weather, hippopotamuses began dying in large numbers along the shores of the Kazinga Channel. Carcasses were found bobbing in the water next to live hippos. The initial theory that the deaths were caused by fighting was ruled out when keepers discovered a number of peaceable females amongst the dead. “When the number became bigger is when I became worried,” says keeper Peter Acheroi. “It had never happened before.”

Park wardens theorised that poaching was to blame, until they saw that the ivory teeth of the animals had been left intact. With the death toll rising, chief wildlife vet Dr Patrick Atimnedi travelled to the park to assess the situation. “Why the consistency in mortalities and why these numbers?” he asks. The decomposing corpses posed a risk to human and animal life, and the gruesome spectacle threatened the park’s burgeoning tourist industry.

Vets began to wonder if the deaths were due to an infection. Dr Risto Heinonen, a Finnish vet based in Africa, thought he recognised the symptoms. “These are criteria that fit very well with anthrax,” he says. Anthrax is spread by spores found naturally in patches of earth. Outbreaks occur occasionally in African countries, but they usually involve more than one species of animal. “How is it that it affects only hippos? Where did it come from?” Heinonen asks.

Samples from an autopsy on one of the dead hippos were sent to Germany for analysis. Epidemiologist Fabian Leendertz concluded that the infection was indeed anthrax. It became a race against time to identify the source of the outbreak before more animals became infected. With the government on a state of alert, workers began burying the corpses in the park. Leendertz flew to Uganda to assist in the operation and quickly ruled out his theory that the water was contaminated.

Leendertz now speculated that the anthrax originated in the hippos’ diet. It was most likely caused by hippos eating plants from infected soil. But infected areas are usually quite small, so how was it that hippos all over the park were dying? The answer came when Leendertz noticed unusual behaviour in the hippos still living in the Kazinga Channel. “Around the carcass there were always other hippos… and they were really interested in the carcass,” he says. “That was a bit suspicious for me.” Then he saw hippos chewing on the carcasses’ intestines, which had been expelled from the body by the gases inside.

Leendertz’s theory held that, with the dry weather killing off vegetation, the hippos had been forced to seek other food sources – including their own kind. But the notion was met with derision – not least because hippos never eat meat. “We have never seen a hippo eating meat, we know that hippos are vegetarian,” says Nicholas Kauta, head of the clean-up operation.

In search of further evidence, Leendertz read an article by a Dr Joseph Dudley, who had witnessed a hippo eating an impala in Zimbabwe. Then footage came to light of a hippo in Malawi eating a hippo carcass. The astonishing theory now seemed irrefutable – hunger-stricken hippos in Uganda were eating the infected corpses of their brethren, only to become infected with anthrax themselves. This explained the spread of the outbreak and why it was restricted to one species. “The hippopotamus then becomes the world’s largest omnivore,” says Dr Dudley, “and, as far as I can tell, the only such mega-omnivore in the past 20 million years.”

Wednesday 14th October 8.00pm

The documentary series examining freak occurrences in the natural world returns. The first instalment of the new run explores a remarkable clash between two oceanic predators. In 1997, stunned tourists on a whale-watching trip off the coast of California witnessed an orca seemingly attack, kill and eat a great white shark – a unique event that gave scientists a radical new perspective on the habits of both species.

Located 27 miles west of San Francisco in the North Pacific, the Farallones are a small group of barren islands that play host to one of the world’s greatest concentrations of great white sharks. Every autumn, the predators flock to the area to feed on the seals that gather on the rocks. Since 1987, scientists based on the islands have been studying the sharks and have built a detailed picture of their behaviour. On 4 October 1997, however, one extraordinary event altered the scientists’ entire perspective.

Marine biologist Peter Pyle was working on the islands when reports came in of a shark attack with a difference. A group of tourists on board whale-watching boat the Superfish had witnessed an orca – very rarely seen near the Farallones – apparently attack a great white. Pyle raced to the scene. “As we approached, you could see the killer whale with a shark in its mouth,” he recalls.

Pyle’s colleague Mary Jane Schramm was on board the Superfish and saw the event unfold. “We were extremely excited,” she says. “It was a very big shark.” Schramm and the tourists were watching two orcas frolic in the waves when the shark appeared. It approached the boat, then swam away – at which point one of the orcas sped towards it. Both animals then disappeared, only for the orca to emerge minutes later with the half-ton shark held upside down in its mouth. “It was like a cat with a mouse,” says Mick Menigoz, skipper of the Superfish. “This was a once-in-a-lifetime thing.”

In the immediate aftermath of the attack, Pyle used a pole camera to record the orcas underwater. The mammals had now torn the shark apart and proceeded to eat parts of it, including the liver. After 15 minutes, they left the area. “It was a complete surprise for us,” says Pyle. “We had no idea that could happen.” While it was clear that an orca had killed and eaten a great white, what was not clear was how the former had overpowered the shark without a struggle. Then within days, an even bigger question arose. After the attack, the entire great white population – up to 100 individuals – suddenly disappeared. What had triggered the departure and where did the sharks go?

With the help of footage of the incident recorded by the tourists, marine biologists surmised that the orca rammed the great white to stun it, then held it upside down to immobilise it. Scientists in the Bahamas have discovered that sharks can be induced into a trance-like state by turning them onto their backs – a condition known as ‘tonic immobility’. Apparently, certain groups of orca have made the same discovery. “Orca are very smart,” says expert Ingrid Visser. “I’m pretty sure that tonic immobility is part of the repertoire of the orca.” Having observed the whales off the coast of New Zealand for many years, Visser thinks it feasible that they could habitually target great whites as food.

As to why the sharks fled after the attack, New Jersey scientist Craig O’Connell believes it was because of the “smell of death” in the water. Tests with lemon sharks show that chemicals released when a shark is killed trigger a violent flight reaction in others of the same species. While this might explain the initial dispersal, however, it does not explain why the great whites would stay away from the Farallones for the rest of the feeding season – especially when later research proved that some of them travel up to 4,000km to be there every autumn.

The bizarre incident at the Farallon Islands still holds some mysteries, but it has shed light on the hierarchy amongst the ocean’s most fearsome killers. “In my mind it’s really clear –we have a top predator here,” says marine biologist Alisa Schulman-Janiger of the orca.

Wednesday 24th December at 8:00pm on five

The documentary series examining freak occurrences in the natural world continues. This instalment explores the growing incidence of lion attacks on humans in east Africa and investigates the reasons behind this sudden shift in behaviour.

Over the last two decades, lion attacks have quadrupled in Tanzania –600 people have been eaten by the beasts since 1990. The government has called in wildlife capture specialists like Dairen Simpson to help cull the problem animals. “We’re not talking about regular old lions,” says Dairen. “We’re talking about lions that walk into a village and kill.”

With a team of government rangers, Dairen heads north to Singida, where a pack of three lions have hunted and killed 20 people in the past year. Although these big cats are a protected species, the threat that some of their number pose to human life has become far too great to ignore. Government ranger Dennis Ikanda theorises that the man-eaters are strategically targeting humans after becoming familiar with their community and environment. “They actively seek human beings as prey, and they do it very well,” he says.

In Singida, the three felines are known to approach a cluster of villages from the road and it is here that the rangers set up a trap. Exactly why certain lions are hunting people instead of zebra, wildebeest and impala is the subject of much deliberation.

Depletion of traditional prey is one popular theory. If there is a lack of food, the predators are forced to
eat livestock instead. While stalking cattle, the big cats come into contact with their human herders. “A smart creature like a lion begins to figure out the easy opportunity,” says Dairen. Human-lion conflict expert Hadas Kushnir has been researching the phenomenon of the man-eater for four years. She is based near the Rufiji River to the south of the country, an area that has also been plagued by lion attacks. Hadas believes that local farming methods make the people in the region vulnerable. The fields are isolated from the villages by bush and must be monitored at night to ensure that the nocturnal bush pigs do not decimate the crops. As bush pigs are another source of prey for lions, the proximity of the slumbering farmers proves too great a temptation. “You get a collision between people and lions with bush pigs as the link,” says Hadas.

Global warming is also a factor in human-lion conflict. In the late 1990s, a spate of attacks coincided with the weather system El Niño. Flooding in Africa meant that game animals had to search for higher ground, and the big cats were forced to look elsewhere for food.

Lion biologist Henry Brink thinks that Tanzania’s conservation programme is also partially to blame for the increase in man-eating lions. Lion numbers have skyrocketed in Selous Game Reserve, which is the second largest protected park in Africa. The big cats spill over into surrounding areas in search of sustenance, but options are limited so they begin to stalk human prey. “What’s a marker to a lion?” says Henry. “It goes where it wants.”

Back in Singida, Dairen and his team have managed to capture two of the three man-eating cats on their black list. Although official culling programmes are having some measure of success, Dairen has concerns that local farmers may begin to kill the creatures indiscriminately. “People will take it into their own hands and begin poison campaigns,” he predicts. “You will not just lose one or two problem lions –you’ll lose all the lions.”

The documentary series examining freak occurrences in the natural world continues. This instalment uncovers the mystery of a group of hideously disfigured Tasmanian devils discovered by scientists in the late 1990s.

The devil is a carnivorous marsupial unique to the Australian island of Tasmania. It is the size of a small, sturdily built dog, and the name ‘devil’ comes from its loud and fiendish shriek. Due to its status as the largest carnivorous marsupial in the world, the animal is of great interest to conservationists and wildlife enthusiasts alike.

One night in 1996, a wildlife photographer set out to capture these fascinating nocturnal creatures on celluloid. The resulting pictures sent shock waves through the scientific community. “What we saw was both disgusting and spectacular,” says Nick Mooney, a biologist who has studied the Tasmanian devil in its natural habitat for 30 years. The pictures showed the devils emerging from the forest with grotesque disfigurements in the form of monstrous facial growths.

It was not until five years later that zoologist Dr Menna Jones came across another group of devils with the same affliction. “They were horrific,” she says. “Teeth falling out, jaws breaking off, tumours protruding into eye sockets.” The growths had all the hallmarks of cancer. But cancer is not contagious, so why were so many devils suffering the same symptoms? “You cannot catch cancer from someone else,” confirms immunologist Professor Greg Woods, “so something unusual was happening with these Tasmanian devils.”

Experts looked to the past for answers. Devils have been extinct on the Australian mainland for over 600 years because they were easy prey for dingoes. Yet the devils were not safe in Tasmania either. For over a century, they were hunted and poisoned by local farmers. It was not until 1941 that a new law was introduced banning anyone from harming the creatures. As a result of inbreeding within the dwindling population, the devils’ immune systems had weakened. This meant their bodies had no defences against foreign cells, and diseases such as cancer became transmissible.

The mystery of the ghastly tumours was eventually solved once and for all when scientists diagnosed the growths as a new type of cancer exclusive to the species – devil facial tumour disease (DFTD). Only two other strains of transmissible cancer have been recorded in the world, making it incredibly rare.

On learning about DFTD, conservationists feared the worst for the future of the devils. “An island is a very finite place, and extinctions have a very nasty habit of occurring on islands,” says Nick. Indeed, DFTD is a particularly aggressive form of cancer, with death almost certainly resulting within three to eight months of contracting the disease. In an attempt to halt the advance of DFTD, authorities launched the Save the Devil Campaign in 2003. Donations made to the cause help fund research into and management of this devastating disease.

Saturday 25th – Friday 31st October

The documentary series examining freak
occurrences in the natural world continues. This
instalment focuses on the circumstances
surrounding the gruesome events of January
2004 when a dead sperm whale exploded in the
middle of a Taiwan street.
At 6.30am on 26 January 2004, police were called
to a grisly scene on a busy street in Tainan, southern
Taiwan. A huge dead body lay on the back of a
truck, while blood and entrails were spread across
the road, nearby cars and shopfronts. All the
stunned bystanders knew was that a whale had just
blown up in the street.
The 50-ton sperm whale – the biggest ever
recorded in Taiwan –was being transported from
the coast where it had washed up 24 hours earlier to
a university for examination. But the journey was
cut short by the unimaginable event. Large parts of
intestine, chunks of blubber and gallons of blood
burst from the tail section of the animal, bringing
traffic to a standstill. “It was just like a horror
movie,” recalls one eyewitness.
Before long, local news cameras arrived on the
scene and began to capture the surreal images.
Journalist Jason Pan realised that he was watching
a major event unfold. “This was the biggest story
I’ve ever been involved with,” he says. “It was kind
of funny in a macabre way.”
The man in charge of transporting the whale was
Professor Wang Chien-ping, of the National Cheng
Kung University, who wanted to perform a
necropsy on the animal. While the rest of the city
cleaned up, the indefatigable professor began the
long, unpleasant process of collecting the
miscellaneous body parts from the street.
The whale eventually reached its destination and
was placed under a huge canopy, where a 60-
strong team of scientists and volunteers started
the immense task of dissecting the animal. By this
time, hundreds of onlookers had gathered to
watch the scientists at work. “This sperm whale
became very famous,” says Professor Wang.
Four years on, the skeleton of the whale is a
popular tourist attraction in Taiwan and its story
has become part of local folklore. But the cause of
the explosion is still the subject of much debate.
Now, a team of international experts attempts to
get to the bottom of the mystery.
In Liverpool, vet Dr Julian Chantrey is convinced that
the explosion was the result of a natural process of
internal putrefaction. “Decomposition is when
organs and tissues start to degenerate,” he says. As a
result of this breakdown, bacteria normally confined
to the gut spread into the abdomen, absorbing the
body’s proteins and generating gases. As these
volatile gases increase, they put pressure on the
abdomen, causing the body to expand. Dr Chantrey
demonstrates this process using a dead pig. “This is a
very small-scale model of how it would be in the
whale,” he explains.
But can this natural process really be responsible for
such destruction? The pattern of body parts strewn
across the street, as well as the sheer power needed
to tear open an animal designed to withstand deepsea
pressure, suggests that something must have
acted as a trigger.
American marine biologist Dr Bruce Mate believes
that the process of moving the whale after its
death must have weakened the body, allowing the
rotten gases to escape in such explosive fashion.
“They had hold of a time bomb,” he says of
Professor Wang and the team. Early footage of the
transportation operation seems to support Dr
Mates’s theory.
But this is no open and shut case – there could yet
be another reason why the whale blew up. After
studying images of the explosion, marine biologist
Michelle Berman theorises that the whale may have
suffered a massive injury while it was still alive. If this
is the case, however, what could inflict such a huge
trauma on the biggest predator on the planet?

The documentary series examining freak occurrences in the natural world returns. Using testimony from scientific experts, interviews with the key players and dramatic reconstructions, the series tells the stories of unique discoveries that have shocked naturalists and led to a broader understanding of the animal kingdom. This first episode examines the discovery of a mysterious animal in a remote part of the Arctic Circle.

In April 2006, hunter Jim Martell set out on an expedition to track down one of the most fearsome creatures on Earth – the polar bear. As the world’s largest land predator, the polar bear has been known to target humans. For Jim, his journey to the remote Banks Island in the Canadian Arctic Circle to confront these beasts was the trip of a lifetime. Accompanied by his Inuit guide, Roger Kuptana, Jim set off in the early hours of the morning, not expecting the drama that would soon follow.

The pair began their quest under dog-sled power, skimming across miles of three-foot-thick frozen sea. Then, after tracking on foot for nearly two hours towards the south-east of the island, they spotted their prize. Jim fired a single bullet, which was enough to fell the beast. But as the men approached the magnificent creature, they were in for a shock.

Roger, a skilled huntsman, realised that this was no ordinary polar bear. In fact, it looked nothing like it should. It had dark rings circling its eyes and, most frightening of all, an unusual hump rising from its back. Roger had never seen anything like it before on the island. The pair alerted the Canadian authorities and made their way back to the mainland with the monstrous body in tow.

When experts viewed the remains, they were unsure what to make of them. In addition, officials claimed that Jim had violated the rights of his hunting permit by shooting an animal that was not a polar bear. Jim faced conviction for a crime he did not commit, despite the having purchased a permit for $40,000. It was now up to scientists to identify this unknown animal and solve a most baffling mystery.

The documentary series examining freak occurrences in the natural world concludes with a look at the discovery of thousands of giant jellyfishin Japanese waters.

On 25th August 2005, Japanese fishermen in the Tsushima Strait made a gruesome discovery as they pulled in their nets. Instead of the expected quota of anchovies and salmon, they had hauled aboard an altogether more deadly catch – thousands of giant Nomura’s jellyfish, with a mass of stinging tentacles and enough venom to kill all of the shocked fishermen. That night, they landed over three tonnes of jellyfish. But little did they know that below the surface, billions more jellyfish were coming up from the deep –some as big as a sumo wrestler.

Net after net was brought aboard containing the same hideous bounty – nothing on this scale had been witnessed before. The fishermen began to slaughter the jellyfish and throw the remains overboard as quickly as they could. But countless more jellyfish were emerging –and heading straight for shore.

Why were these monsters of the deep heading inland?

In Australia –one of the first countries in the firing line of this apparent attack – leading jellyfish expert Dr Jamie Seymour wanted to find out. “They are not just drifting around there like a block of jelly in the ocean,” he explains. “They are making active movements. They know where they want to go –and they can get there at speed.” As well as speed, some jellyfish also have lethal poison. Irukandji and box jellyfish have killed more people in Australia than great white sharks and crocodiles combined, so scientists had to race against time to find an effective anti-venom and treatment. Tonight’s film tells the story of how scientists prepared for the coming invasion, and investigates the threat that still remains.

The documentary sees experts travel around the world diving into the centre of jellyfish swarms to discover what motivates these giant predators. It uncovers the incredible findings from the Japanese research teams in the Tsushima Strait, and investigates the extraordinary experiments that have led scientists to amazing new insights.

TUESDAY FEBRUARY 5 / 8:00pm

nature shock
the zombie alligators (5/6)

The documentary series examining freak occurrences in the natural world continues. This programme focuses on a bizarre chain of events in Lake Griffin, Florida, which turned a once peaceful wilderness into a scene reminiscent of a horror film. Over a period of years, a number of Griffin’s resident alligators were turning up dead, but scientists were baffled as to the cause.

In May 1997, the bloated bodies of a number of adult alligators were discovered on the shoreline of Lake Griffin in central Florida. “There were times when I would go into the lake and find ten alligators within half a mile,” recalls local fisherman Skip Goerner. The reports of these strange deaths caught the attention of the Florida state’s Fish and Wildlife Conservation Commission (FWC), who sent a team to look into the mystery. Leading the investigation was wildlife biologist Allan Woodward who immediately suspected the work of poachers. However, the corpses told a different story –they bore no signs of attack by man and, most shockingly of all, some of the motionless animals were not even dead.

In order to discover the cause of these events, the FWC team began to study the behaviour of the alligators before they died. What the scientists found was that the animals were struggling to move properly and keep their heads above water, with many alligators spending much of their time floating listlessly in the lake or lying motionless on the banks. “We noticed alligators that showed poor equilibrium,” says Woodward. But why would these amphibious creatures who have survived for millions of years suddenly be unable to survive in their natural environment?

Pathologist Dr Scott Terrell conducted thorough autopsies on the alligators, but he could find no clues as to the cause of death. “What we were seeing were adult, healthy animals,” he recalls. “We weren’t finding much.”

Since the dead bodies were offering no evidence, the scientists returned to the lake and went in search of a living ‘zombie’ alligator. Soon, they had caught one such animal –an unusually easy manoeuvre since the alligator was incapable of putting up a fight. A sample of blood was taken from the animal and sent to Mark Merchant –a professor of biochemistry at McNeese State University. But Merchant could find no sign of any illnes. In fact, he attempted to infect the blood with a number of deadly viruses, including E. coli, salmonella and HIV, but each time the incredibly resistant blood fought off the infection.

Having drawn another blank, the scientists returned to their living specimen. “Some of the signs we saw did suggest some neurological problems,” says Woodward. “That became our next suspect.” Tests showed that the animal responded in a slow and unpredictable way to electrical stimulation, suggesting that the problem did lie somewhere in the nervous system –but it was still not clear where. Dr Terrell suspected that the key to the mystery lay in the alligator’s brain –an organ weighing just eight grammes. He sent tissue samples for tests and soon discovered that many of the neurons in the animal’s brain had died. “There were areas of the tissue that were almost ghost-like,” he says.

This brain damage explained all the symptoms common among the alligators, including disorientation, loss of balance, nerve damage and drowning –it seemed that for some reason, portions of these alligators’ brains were dying while they were still alive. However, despite their breakthrough, the scientists were still no closer to finding the culprit for the animal deaths.

The FWC suspected that man’s activites were responsible and began to focus on the change in water quality caused by increased agricultural activity on the banks of the river. However, it was not until a chance meeting with a man called Dr Dale Honeyfield at a scientific conference in Maryland that Woodward and his team would finally get to the bottom of the case. Could something as simple as a vitamin deficiency be responsible for such a strange turn of events?

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