Wednesday, August 13, 2008

seal stories

I was intrigued by the following story in Agence France Presse. It interested me that elephant seals swim under the Antarctic ice floes and I appreciated the immaginative use of this behavior pattern. I was also surprised they didn't include a photo of these huge animals. Looking for a photo, I found another story, also cited below. I wasn't surprised that the current story didn't reference the earlier one, but wouldn't it be a good thing for reporters to do a little research so as to provide some additional background, and not just re-write what they're given in press releases?
Seals give scientists unique glimpse under Antarctic ice, by Lawrence Bartlett Tue Aug 12, 10:35 AM ET


SYDNEY (AFP) - Huge elephant seals have been recruited to help scientists break through a critical blind spot and chart climate change under the Antarctic sea ice in winter, researchers said Tuesday.

The seals, which can weigh up to three tonnes, are fitted with sensors that transmit previously unavailable data to satellites when they surface to breathe.

The seals measure temperature, salinity and depth as they dive up to nearly two kilometres (1.25 miles) and cover distances of up to 65 kilometres a day.

They have provided a 30-fold increase in data over conventional methods.

The polar regions play an important role in the Earth's climate system and are changing more rapidly than any other part of the world, with the potential to accelerate the rate of change elsewhere, scientists say.

The sensors, about the size of a mobile phone, are fitted when the seals return to sub-Antarctic islands to breed and to moult during the summer.

Once they have grown the next season's fur, the sensors are glued to the fur on the back of the animal's head, so when it surfaces to breathe the sensor is out of the water and the antennae can transmit the data to satellite.

Though the seals are not particularly concerned about humans and scientists can approach them quite close, the animals are sedated with a syringe on the end of a pole to ensure the sensors can be attached safely.

The sensors stay on through the winter season and fall off when the seals return to the islands and shed their fur for the summer.
A quick search of Google Images turned up a large number of good photos. The most interesting was part of a NASA release which tells the story from a different viewpoint:
Mission News Satellites and Sea Lions: Working Together to Improve Ocean Models, by Rosemary Sullivant, 02.06.07


The best oceanographers in the world never studied at a university. Yet they know how to navigate expertly along oceanic fronts, the invisible boundaries between waters of different temperatures and densities. These ocean experts can find rich fishing in places and at depths that others would assume are barren. They regularly visit the most interesting and dynamic parts of the sea.

Sea lions, seals, sharks, tuna and other top ocean predators share some of their experiences with human researchers, thanks to electronic tags. Besides tracking the animals, these sensors also collect oceanographic data, such as temperature and salinity. Scientists are beginning to incorporate this rich store of information into ocean models providing new insights into the inner workings of the ocean and the lives of its creatures.

"Our goal is to produce a three-dimensional model of the ocean," says JPL oceanographer Dr. Yi Chao. Chao uses data from satellites, ships, buoys and floats to map the currents, heat content and different water densities beneath the ocean surface.

"Satellites provide a two-dimensional view of the ocean," says Chao. "Animals give us a slice of the ocean. They're like weather balloons in reverse."

"We are at the forefront of knowing how animals use the ocean," says [Chao's collaborator] Costa. "But we want to understand the environment better. We still see the ocean primarily as deep or shallow or near-shore or offshore. But just as there are different habitats on land, the ocean has fine-scale features that are very important to animals," he explains. "We want to be able to look at the ocean and say the equivalent of "this is a grassland" or "this is a forest."

In late January, Costa and his research group headed up the California coast to begin tagging elephant seals and collecting tags that were deployed last spring. The work is strictly regulated to ensure that the animals are protected from harm, and it requires a permit from the National Marine Fisheries Service.

"Marine scientists have been tracking marine animals for years," says Chao. "It's an interesting challenge, though, to use the data. There are all sorts-- from tuna, sharks, seals--you name it. Some of these data sets have small errors, others much larger errors. Figuring out how to put these in our system is a challenge, "he says. "But five years from now, we should be able to see the ocean the way a turtle sees it."

What is most important about using marine animals as ocean sensors is that the work benefits the animals, Costa explains. "Collaborations between biologists and physical oceanographers are critical for understanding why the animals go where they go," he says, "as we need to know and understand the ocean physics and its relationship to climate processes. Further, the ability to understand how climate change is affecting the world oceans is not only of benefit to humans, but is vital for trying figure out what is going to happen to habitat of marine animals."
Here are a couple of images from the NASA site:

The field team attaches a tag to the fur of a sedated male elephant seal. Special permits are required for this work to ensure the animal's protection. Image credit: Daniel Costa

A male sea lion shares his intimate knowledge of the ocean with researchers via an electronic tag. Image credit: Mike Weise

And here are a couple more from Cathy Webster on her own web site.

South Georgia, St. Andrew's Bay, adult male elephant seal

South Georgia, St. Andrew's Bay, me talking to a young elephant seal

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