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January 4, 2011

Undersea Weather

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  Watching El Niño
(10.08.04) - While hurricanes and typhoons are large destructive forces that cost lives and destroy property, climatologists are on the lookout for something in the ocean that operates on an even grander scale. They now are carefully watching and learning as much as they can about this phenomenon.

Seas and Climate
(02.19.04) - A worldwide system of ocean floats is on its way to helping scientists forecast potentially devastating events like floods or droughts months or even years in advance.

Old El Niño
(10.25.00) - Researchers have found a way to study the El Niños and La Niñas of the past, with the help of coral reefs. And a new study raises the question of whether the weather extremes are likely to continue, and even get worse.


Deep-sea life

Effects of El Niño

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The extreme weather that impacts us is now having an effect where you might least expect it - deep under the sea. As this ScienCentral News video explains, scientists have linked climate change to population booms and busts in deep-sea life.

Not-So-Sunny Underwater Forecast

Warm waters might be soothing in a bathtub or a swimming pool but when the ocean heats up it can get mighty uncomfortable, and even deadly, not only for the animals who live there but for land lovers too. Peruvian and Ecuadorean fishermen even coined a term for the warm water phenomenon in the late 1800s, El Niño, their nickname for unusual Christmastime changes in water temperature that impacted their catch; El Niño has since been shown to cause extreme weather conditions like hurricanes and droughts.

Now scientists say that El Niño and La Niña - when ocean temperature in the Equatorial Pacific grows colder than normal compared to El Niño - are not only impacting life on land and on the sea surface, but also life on the ocean floor. Deep-sea ecologist Henry Ruhl, working with colleagues at Scripps Institution of Oceanography, reported in the journal Science that changes in surface ocean climate may be impacting animal populations far under the ocean.

image: Milton Love
"The sea life populations were changing in a way that suggested that climate was linked to food supply, and food supply was linked to the abundance of the animals in the seafloor on time scales that were roughly similar to what we were finding in above-water systems," Ruhl explains. "So it seems plausible that climate could be affecting the deep sea relatively rapidly, and wasn't somehow far removed in time, even though it's out of sight, out of mind to many people." But he's quick to add that more research is needed to find the specific causes of the population jumps or declines he reported.

At "Station M," 130 miles off the California Coast, the Scripps team has been studying an abyss 13,400-feet deep since 1989. They set out to document something many agree they know little about - what happens deep beneath the sea. Using a submersible camera-mounted sled that snapped photos of ocean life every five seconds, researchers tracked ten mobile animal populations, including starfish and sea cucumbers. They took ocean floor samples of nutrient-packed sludge called sediment, a mix of feces and dead phytoplankton, amongst other things, that sinks from the sea surface and provides food to animals on the seafloor. Then, the team compared sediment composition to changes in time and weather.

The information gave Ruhl a more complete picture of how deep-sea marine animals may be impacted by climate change. "We believe that food supply is one of the only plausible mechanisms for the climate to be affecting the animals on the seafloor," he says. "And we believe it's happening through a mechanism in which climate affects the productivity or the amount of sea life above the study site on the overlying surface waters."

El Nino Satelite
Satelite imaging of climate changes and ocean temperatures produced by El Nino.
image: NOAA
It's there that phytoplankton float on the ocean surface, where they grow by soaking up the sun and taking in nutrients like iron. The problem is that phytoplankton is also highly sensitive to a domino effect brought on by climate changes. During an El Niño event, wind patterns and ocean circulation change. One result is a slowdown in something called upwelling, the upward flow of cold, heavy, deep-sea water resulting when off shore currents draw warm surface water away from the coast. Upwelling floods ocean surface water with nutrients. But when this nutrient rich water fails to reach areas where phytoplankton live, as happens during an El Niño event, phytoplankton slowly starve. In turn, other sea life that depend on phytoplankton as a food source start dying too. Ruhl believes that these kinds of changes in sea surface life directly "affects the population of the animals in the sea floor."

Experts say scientists are getting better at spotting El Niño events ahead of time, even though solutions to the problem, and the subsequent impact it has on sea life, aren't so forthcoming. The National Oceanographic and Atmospheric Administration (NOAA) is one agency that tracks El Niño. Scientists there were able to predict the 1997-1998 El Niño six months ahead of its arrival, using instrumentation like satellites and ocean buoy data. Their predictions saved California over a billion dollars since the state was able to prepare for the event ahead of time.

So, should we be putting the sea cucumber up there with other endangered species? Not yet. Ruhl says that what we do with the information uncovered in the study is "really a values question...not in our lifetime will we be affected by what happens in the deep sea, other than knowing that it's happening."

It's in a hundred years or more that people will have to fish for solutions to much bigger problems down below.

       email to a friend by Stacey Young

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