EL PAÍS offers the América Futura section openly for its daily and global information contribution on sustainable development.
If you want to support our journalism, subscribe
here
.
On January 23, a group of Chilean scientists and a British man crossed to Tierra del Fuego through the Strait of Magellan to Caleta María, a small ranch half an hour away from Bahía Jackson, in the extreme south of Chile.
They came there looking for the only large resident population of elephant seals (
Mirounga leonina
) in the country, which can number up to 160 individuals between October and November, the reproductive months, according to the
Wildlife Conservation Society
.
After this period, the elephant seals shed their skin and hair, and return to their journeys through the seas at the end of the world.
“We needed to catch animals that had already molted, but had not yet left,” says Maritza Sepúlveda, a marine ecologist at the University of Valparaíso, who leads a project that uses these pinnipeds to act as explorers and collect ocean data in the southern end.
To place the satellite transmitters on them, the scientists had to make sure that the animals had already shed their fur so that it did not come off their skin.
The researchers chose some of these seals—three males and three females—and put the devices on them.
Its objective was twofold: to capture data from the ocean and these marine mammals.
Elephant seals were chosen because they are great divers: they can go down to 2,000 meters deep, explains Manuel Castillo, an oceanographer at the University of Valparaíso.
With the data they collect, every time they emerge to the surface, the device connects with the satellite, the information is triangulated and scientists can review it on a web page.
Chilean researchers mount a satellite transmitter on a seal.
The study that this group of scientists is doing measures the structure of these waters, which involves taking data at different depths.
And this was a “unique opportunity,” says Castillo.
“It's very difficult to do it with the typical way we use.
We usually go in a boat, we take our instruments and we go down,” he says when describing the traditional method of exploration.
But it is a “super complicated logistically” feat, as well as expensive and complex, especially in the rugged southern channels and fjords.
“The elephant seal was ideal and it was already proven that it had these abilities to go deep and make multiple dives,” he highlights.
Likewise, unlike whales and dolphins, they later congregate in the same place: “They move, but then they return to a place where you can bump into them,” he says.
“There are different ways to take advantage of technology in organisms in a passive way, and not stress them so much.”
The dirty work
On rocky beaches, loaded with algae and trees that are stranded in the bay pushed by the current, the seals rest, while inland the grasslands of the cold steppe persist.
“There the elephant seals are very calm,” describes Sepúlveda.
Between strong winds, seagulls, cormorants, bandurrias and solitary condors that flew over the nearby hills - from where a waterfall fell from a glacier - the scientists chose which individuals to anesthetize and put the transmitters on.
Among sea seals, dominant males measure up to five meters, being much larger than females;
something that is not common in pinnipeds, which usually present little sexual dimorphism: “The other species are more monogamous, so the males do not have to compete with each other, so the difference between the sexes is little,” explains the expert.
As she puts it, “there is no other mammal” that has so many females under its dominion, dozens.
So larger males were not candidates for anesthetization.
“The ones we did put transmitters on were not so big,” details Sepúlveda, and she adds that, since they were not in the reproductive period, they were not so hostile.
The tide was another factor to take into account.
If it rose and the animal was half asleep, it was risky to execute the maneuver.
They were attentive.
The veterinarian Josefina Gutiérrez calculated what dose to apply according to their size, until they relaxed and were anesthetized.
Once asleep, nasal and blood samples were taken for studies.
“Since we have the animals asleep, we have to get the juice out of them,” she says.
After cleaning their skin with acetone, they glued the transmitters to their hair with a harmless substance for ten minutes to leave them well adhered, while the specialist monitored the heartbeats and respirations of the sedated animal.
Aware of the bird flu epidemic that has killed thousands of marine mammals in the southern continent in recent years, the researchers followed a strict clothing protocol.
“The work was at all times in pursuit of the seal's well-being, which was the most important thing,” highlights the ecologist.
“We didn't have any problems with the animals.”
During the weeks of molting, the seals spend long hours lying down, while the juveniles often get into the water, and they play fighting and bumping necks among themselves, as they will also do as adults, although with more violence.
Among sea seals, males can measure up to five meters, much larger than females.
Another difficulty in anesthetizing pinnipeds is that when sedated they can go into apnea, from which, in the worst case, they do not wake up.
“You couldn't work in the rain because it could encourage the animal to go 'diving,'” he explains;
They must have been dry, no more than a drizzle.
“It happened to us with an animal that had an apnea for three minutes and then continued to breathe normally,” he says.
Now, after returning to the water, the six seals are expected to transmit data for eight or nine months.
It will depend, among other factors, on the instruments' battery, since at greater depths, about 100 meters and about 5°C, the charge lasts less.
mysterious waters
“
The Cape Horn Current has been little studied: almost no basic oceanographic parameters such as changes in temperature, salinity and chlorophyll are known,” says Sepúlveda.
With the advancement of technology, they opted for these “living monitors” that, with their routine of moving and feeding, take data like “3D oceanographic sensors.”
That is to say, “they are explorer seals”, he points out that these divers weigh a ton and have the adaptations—such as blood capable of containing a lot of oxygen—to spend dozens of minutes submerged.
“When you go to the doctor, you feel bad and you don't know what you have.
The doctor says 'do some tests', because this way he obtains data that he can compare with the normal ranges to know if there is any disease," says Castillo.
This is exactly what they are looking for when exploring the ocean through seals.
Some key data are temperature and salinity at different depths and heights, from the surface to the bottom.
The fluorescence or “concentration of organisms that carry out photosynthesis, or phytoplankton” is also taken.
Likewise, they take the PH and oxygen levels, which “is super relevant;
“It gives an idea of the general state of health of the bodies of water,” he remarks.
But while oceanographers study these seas, ecologists want to know about these divers.
For example, where they go or how much they dive.
“We are doing two major investigations within one,” says Sepúlveda.
“It's very original.”
Researchers also seek to have more information about the area, known as Almirantazgo Fjord, west of the Big Island of Tierra del Fuego.
They lowered an instrument, called CTD (Conductivity, Temperature, Depth), almost to the bottom of the sea to make “profiles” of those sites and obtain new information different from what the National Oceanographic Committee, led by the Chilean Navy, has achieved. occasionally with a ship.
Elephant seals in the waters of Jackson Bay.SONJA_HEINRICH (Nataly Oyarzún)
Some preliminary data that they have obtained with this new project, according to Castillo, is that because the glacier in front is melting due to increasing temperatures, the waters of the fjord - that is, the deep gulf between mountains - are low in salt.
“It is not very saline,” he says, “but then deep down it recovers the salinity.”
They have also noticed a “large accumulation of chlorophyll” ten meters from the surface: “It is curious because the organisms that carry out photosynthesis typically like to be higher up and, in this case, they are lower down.”
This is something that “was not so described”, despite being “typical” of canals and fjords.
In these weeks, some seals have already left Jackson Bay and have surpassed the 500 meter deep dives.
“The beautiful thing is that they are already telling us that they are traveling, moving through the area that interests us and beginning to connect the fluorometry, temperature and salinity data,” highlights Sepúlveda, who is also interested in knowing what their migrations are like, because “ Very little is known”... Will they return to the same place at the end of the year?
He doesn't know it, although he hopes so.