One whale of a history lesson

Discovery of whale bones in salt flats offer environmental information of seven millenia ago.

ABU DHABI // The remains of an ancient whale discovered in Abu Dhabi have given scientists a glimpse into the capital's marine environment seven millennia ago.

The discovery, in what is today the Mussafah industrial area, also highlights the importance of preserving the capital's sabkhas - low-lying coastal salt flats of unique geological significance that are currently under threat because of rapid development.

A study of the sabkhas led to the discovery of the whale bones. Part of a large bone, protruding from an excavation wall of what was later to become the Musaffah Channel, was spotted by oil-industry geologists.

The geologists' interest in the sabkhas is not unusual. The salt flats and the carbonate sediments just below them "are studied by the oil industry because they are a more recent version of older sediments that have oil in them", said Dr John Stewart, who has studied the whale remains. The older sediments are deep underground, while the new ones are close to the surface.

In 2008, two years after the bones were first spotted, Dr Stewart, a lecturer in paeleoecology and environmental change at Bournemouth University in the United Kingdom, visited the site with a colleague, Nigel Larkin, and a number of scientists from Abu Dhabi. The bones were studied and the most important finds removed from the site. The team, which includes a total of 15 authors, published a paper this month announcing their finds to the scientific community.

"It was one of those accidental discoveries telling a story about Abu Dhabi's history and its marine environment," said Dr Mark Beech, cultural landscapes manager at the Abu Dhabi Authority for Culture and Heritage.

The remains consisted of both jaws of the whale, its skull, a shoulder blade, some ribs, and bones from the flipper. To put the size in perspective, the left lower jaw bone is 4 metres long. The shape of the jaw, as well as the presence of barnacles known to live on the skin of a particular species, led scientists to believe that the skeleton most likely was that of a humpback whale.

The scientists believe the remains are of just one animal, which died at sea and floated into a shallow lagoon similar to the ones Abu Dhabi has currently. The theory is supported by the fact the whale bones were discovered upside down.

"Animals such as whales and dugongs often turn upside down when they are dead as their stomach fills up with gas," Dr Beech said.

To determine the age of the remains, scientists took samples of the sediment under the bones, and around and above them. Radiocarbon dating showed the bones to be between 5,500 and 7,000 years old. This, said Dr Beech, corresponds to the Neolithic period, a time when humans had already populated the Arabian Peninsula.

While the remains are an "interesting find", the story told by the sediments in which they were deposited is arguably a more important one, said Dr Stewart.

"Before we did this, no one had really studied the animals in the sediments that the whale was found in," he said.

Particularly interesting was the study of what scientists call microfossils, the remains of tiny animals not larger than four millimetres. There were fewer small crustacean and plankton species present in the ancient lagoon compared to the diversity of today. This led the team to determine that salinity levels in the ancient lagoon were higher than what is now considered the norm.

This interpretation coincides with other data which shows that at that time the climate was changing, turning the area into the desert of today.

"One reason that the salinity may have been higher was that this was a particularly warm and particularly dry period," Dr Stewart said. "This is the link we made with the big picture."

The scientists also believe the sea level at that time was 1 to 2 metres higher than it is today, showing potential outcomes in the future due to climate change.

The site where the bones were discovered has since been filled with gravel and is 30 metres from a major road. The bones are being kept at a special facility in Al Ain, said Dr Beech, who hopes his department will one day be able to show them to members of the public.

An exhibit could include a replica of what the whale might have looked like, and the bones themselves with an explanation of the story they tell.

"In places like the Natural History Museum in the UK and similar museums around the world, people usually spend a couple of years preparing displays," Dr Beech said. "It will be great to exhibit this in future."