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Scientists probe mysterious wave of antelope deaths

 Scientists probe mysterious wave of antelope deaths

By Rory Galloway
BBC Science writer

Around 120,000 Saiga antelope have died so far

Around half of the world’s critically endangered Saiga antelope have died suddenly in Kazakhstan since 10 May.

An unknown environmental trigger is thought to have caused two types of normally benign bacteria found in the antelopes’ gut to turn deadly.

The animals die within hours of showing symptoms, which include depression, diarrhoea and frothing at the mouth.

Because it is calving season, entire herds of female antelope and their new-born calves have been wiped out.

“They get into respiratory problems, they can’t breathe easily. They stop eating and are extremely depressed; the mothers die and then the calves are very distressed and then they die maybe one or two days later,” said Richard Kock from the Royal Veterinary College in London.

Prof Kock spoke to the BBC’s Science in Action programme after joining an international team in Kazakhstan studying the causes of the die-off.

Conservation setback

The Saiga antelope is a species adapted to cope with the extremes of temperature found on the central Asian steppes of Kazakhstan. They are about the size of a large sheep and once roamed in their millions from Great Britain to northern China.

Populations have fallen repeatedly due to hunting, reaching a low of around 50,000 individuals after the fall of the Soviet Union. This rendered the species critically endangered.

Hunting brought Saiga numbers to a low of 50,000 in the 1990s

Conservationists have made great progress with Saiga in recent years, due to international efforts to reduce poaching and monitor their populations.

This die-off is a severe setback to the conservation effort because it has wiped out four of the six calving herds in the largest remaining – and best protected – “Betpak-dala” population, in central Kazakhstan.

Steffen Zuther, head of the Association for the Conservation of Biodiversity in Kazakhstan (ACBK), was monitoring calving in one of the herds containing thousands of affected animals.

“Over two days [in the herd I was studying] 80% of the calving population died,” he told the BBC.

The whole herd then died within two weeks.

Steffen Zuther has been monitoring herds of antelope in Kazakhstan

About 120,000 individual antelope have died, from a global population of approximately 250,000. Fortunately, mortality rates are now dropping, although the deaths continue in some populations.

“What we’re seeing is sort of a perfect storm of different factors,” Prof Kock explained.
Two different bacteria, pasteurelosis and clostridia, have been found in every dead animal studied. These bacteria are naturally found in the animals’ respiratory and gut systems, so something must have reduced the immunity of the animals.

One possible trigger is climatic. This year a very cold winter was followed by a wet spring, and this may have affected the immune competence of the animals, making them more vulnerable to the bacteria.

This, or some other trigger, pushed the animals past a threshold at which the bacteria overcame Saiga immune defences and became deadly enough to transmit to their calves.
dead antelope and calf

Because of its timing, the wave of deaths has claimed mothers and calves
“There’s no infectious disease that can work like this,” said Prof Kock. He added that the wave of Saiga deaths was not unprecedented. “[This] die-off syndrome has occurred on a number of occasions.”

In 1984, 2010 and 2012 there were massive die-offs, but none of these claimed such a massive proportion of the population. ‘Doesn’t make sense’

Despite these huge losses, Saiga antelope are surprisingly well adapted to recover quickly from population crashes.

“Its strategy for survival is based on a high reproductive rate, so [the Saiga] produce triplets and have the highest foetal biomass of any mammal. It’s built, in a sense, to recover from collapse,” Prof Kock said.

The Saiga’s natural habitat has dramatic temperature fluctuations. “In a very severe winter… you could lose 90% of the population.”

But losing 100% percent of some populations within two weeks “doesn’t make any sense” from a biological or evolutionary perspective, Prof Kock said.

There are five main populations of Saiga remaining in central Asia

Saiga antelope have been a conservation success story after recovering from their critical low in the 1990s. The animals now exist in five locations across central Asia, but all individuals affected by the sudden die-off are from the largest remaining Betpak-dala population in Kazakhstan.

This population consists of six major herds, of which four have been completely wiped out.

Steffen Zuther is going back into the field to investigate more remote populations. He hopes to identify what triggered this population collapse, so he can work to stop it happening again.


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Mapping Earth’s Magnetic Fields

By Jonathan Amos Science correspondent, BBC News

A field snapshot in June. Reds are strong; blues are weak. The view is dominated by the core contribution

Europe’s Swarm space mission has begun making maps of Earth’s magnetic field. Data just released shows how the field generated in the planet’s liquid outer core varies in strength over the course of a few months. Swarm’s early assessment appears to support the prevailing view that this magnetic cloak in general is weakening. Many experts believe it heralds a flip in the poles, where north becomes south and vice versa, although it would take thousands of years to complete. The European Space Agency’s Swarm mission was launched last November. It comprises three satellites that are equipped with a variety of instruments – the key ones being state-of-the-art magnetometers that measure field strength and direction. They fly in a configuration that offsets one platform from the other two. The intention is that this should provide a three-dimensional view of the field, and make it easier to tease apart its various components. In the release this week from Esa, we get a view that is dominated by the contribution (95%) from the core. But eventually, Swarm will have the sensitivity to describe magnetism from other, more subtle sources, including that generated by the movement of our salt-water oceans.

Change in the field since January. Reds are a strengthening; blues are a weakening

The maps on this page use the magnetic unit of a nanoTesla. Earth’s field typically has a full strength of some 50,000nT. The maps illustrate a snapshot (in June) and the change that occurs through time (January to June). In the latter, field strength is seen to drop over the western hemisphere but rise in other areas, such as the southern Indian Ocean. Earth’s magnetic field is worthy of study because it is the vital shield that protects the planet from all the charged particles streaming off the Sun. Without it, those particles would strip away the atmosphere, just as they have done at Mars. Investigating the magnetic field also has direct practical benefits, such as improving the reliability of satellite navigation systems which can be affected by magnetic and electrical conditions high in the atmosphere. “I started my career in magnetometry and the accuracy we had then in the laboratories was less than what we can fly in space now,” explained Prof Volker Liebig, the director of Earth observation at Esa. “So what we have on Swarm is fantastic, but we need long time series to understand fully the Earth’s magnetic field, and we will get that from this mission,” he told BBC News.

The Swarm fly high above the Earth in a configuration that offsets one satellite from a pair of spacecraft

Has the Earth already been mapped by Aliens? Do Aliens even exist? Some people say yes, others no. Here’s an interesting perspective from one of NASA’s astronauts including Story Musgrave and SETI’s Seth Shostack. http://youtu.be/MBK6eHWbwNc

 

Prehistoric North Sea Atlantis hit by 5 metre tsunami

By Paul Rincon
Science editor, BBC News website

A prehistoric “Atlantis” in the North Sea may have been abandoned after being hit by a 5m tsunami 8,200 years ago.

The wave was generated by a catastrophic subsea landslide off the coast of Norway.

Analysis suggests the tsunami over-ran Doggerland, a low-lying landmass that has since vanished beneath the waves.

“It was abandoned by Mesolithic tribes about 8,000 years ago, which is when the Storegga slide happened,” said Dr Jon Hill from Imperial College London.

The wave could have wiped out the last people to occupy this island.

The research has been submitted to the journal Ocean Modelling and is being presented at the European Geosciences Union General Assembly in Vienna this week.

Dr Hill and his Imperial-based colleagues Gareth Collins, Alexandros Avdis, Stephan Kramer and Matthew Piggott used computer simulations to explore the likely effects of the Norwegian landslide.

He told BBC News: “We were the first ever group to model the Storegga tsunami with Doggerland in place. Previous studies have used the modern bathymetry (ocean depth).”

As such, the study gives the most detailed insight yet into the likely impacts of the huge landslip and its associated tsunami wave on this lost landmass.


During the last Ice Age, sea levels were much lower; at its maximum extent Doggerland connected Britain to mainland Europe.

It was possible for human hunters to walk from what is now northern Germany across to East Anglia.

But from 20,000 years ago, sea levels began to rise, gradually flooding the vast landscape.

By around 10,000 years ago, the area would still have been one of the richest areas for hunting, fishing and fowling (bird catching) in Europe.

A large freshwater basin occupied the centre of Doggerland, fed by the River Thames from the west and by the Rhine in the east. Its lagoons, marshes and mudflats would have been a haven for wildlife.

“In Mesolithic times, this was paradise,” explained Bernhard Weninger, from the University of Cologne in Germany, who was not involved with the present study.

But 2,000 years later, Doggerland had become a low-lying, marshy island covering an area about the size of Wales.

The North Sea has given up wonderful prehistoric finds, like these bone points now kept at the National Museum of Antiquities in Leiden, The Netherlands

This shaft-hole pick made from antler was found near Rotterdam in the Netherlands

The nets of North Sea fishing boats have pulled up a wealth of prehistoric bones belonging to the animals that once roamed this prehistoric “Garden of Eden”.

But the waters have also given up a smaller cache of ancient human remains and artefacts from which scientists have been able to obtain radiocarbon dates.

And they show that none of these relics of Mesolithic habitation on Doggerland occur later than the time of the tsunami.

The Storegga slide involved the collapse of some 3,000 cubic km of sediment.

“If you took that sediment and laid it over Scotland, it would cover it to a depth of 8m,” said Dr Hill.

Given that the majority of Doggerland was by this time less than 5m in height, it would have experienced widespread flooding.

These young Mesolithic women from Teviec, Brittany, were brutally murdered. As sea levels rose competition for resources may have intensified

“It is therefore plausible that the Storegga slide was indeed the cause of the abandonment of Doggerland in the Mesolithic,” the team writes in their Ocean Modelling paper.

Dr Hill told BBC News: “The impact on anyone who was living on Doggerland at the time would have been massive – comparable to the Japanese tsunami of 2011.”

But Bernhard Weninger suspects that Doggerland had already been vacated by the time of the Storegga slide.

“There may have been a few people coming with boats to fish, but I doubt it was continuously settled,” he explained.

“I think it was so wet by this time that the good days of Doggerland were already gone.”

Prof Vince Gaffney, an archaeologist at the University of Birmingham, said: “I think they (the researchers) are probably right, because the tsunami would have been a catastrophic event.”

But he stressed that the archaeological record was sparse, and explained that two axes from the Neolithic period (after Storegga) had been retrieved from the North Sea’s Brown Banks area.

It is possible these were dropped from a boat – accidentally or as a ritual offering – but it is also unclear precisely when Doggerland finally succumbed to the waves.

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