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LOS ANGELES, June 17 (Xinhua) -- The size of low-oxygen zones created by respiring bacteria is extremely sensitive to changes in depth caused by oscillations in climate, thus posing a distant threat to marine life, a new study suggests."The growth of low-oxygen regions is cause for concern because of the detrimental effects on marine populations -- entire ecosystems can die off when marine life cannot escape the low- oxygen water," said lead researcher Curtis Deutsch, assistant professor of atmospheric and oceanic sciences at University of California, Los Angeles."There are widespread areas of the ocean where marine life has had to flee or develop very peculiar adaptations to survive in low- oxygen conditions," Deutsch said in the study to be published in an upcoming print edition of the journal Science.A team led byDeutsch used a specialized computer simulation to demonstrate for the first time that fluctuations in climate can drastically affect the habitability of marine ecosystems.The study also showed that in addition to consuming oxygen, marine bacteria are causing the depletion of nitrogen, an essential nutrient necessary for the survival of most types of algae."We found there is a mechanism that connects climate and its effect on oxygen to the removal of nitrogen from the ocean," Deutsch said. "Our climate acts to change the total amount of nutrients in the ocean over the timescale of decades."Low-oxygen zones are created by bacteria living in the deeper layers of the ocean that consume oxygen by feeding on dead algae that settle from the surface. Just as mountain climbers might feel adverse effects at high altitudes from a lack of air, marine animals that require oxygen to breathe find it difficult or impossible to live in these oxygen-depleted environments, Deutsch said.Sea surface temperatures vary over the course of decades through a climate pattern called the Pacific Decadal Oscillation, during which small changes in depth occur for existing low-oxygen regions, Deutsch said. Low-oxygen regions that rise to warmer, shallower waters expand as bacteria become more active; regions that sink to colder, deeper waters shrink as the bacteria become more sluggish, as if placed in a refrigerator."We have shown for the first time that these low-oxygen regions are intrinsically very sensitive to small changes in climate," Deutsch said in remarks published Friday by the American Association for the Advancement of Science on its website. "That is what makes the growth and shrinkage of these low-oxygen regions so dramatic."Molecular oxygen from the atmosphere dissolves in sea water at the surface and is transported to deeper levels by ocean circulation currents, where it is consumed by bacteria, Deutsch said."The oxygen consumed by bacteria within the deeper layers of the ocean is replaced by water circulating through the ocean," he said. "The water is constantly stirring itself up, allowing the deeper parts to occasionally take a breath from the atmosphere."A lack of oxygen is not the only thing fish and other marine life must contend with, according to Deutsch. When oxygen is very low, the bacteria will begin to consume nitrogen, one of the most important nutrients that sustain marine life."Almost all algae, the very base of the food chain, use nitrogen to stay alive," Deutsch said. "As these low-oxygen regions expand and contract, the amount of nutrients available to keep the algae alive at the surface of the ocean goes up and down. "Understanding the causes of oxygen and nitrogen depletion in the ocean is important for determining the effect on fisheries and fish populations, he said.

WASHINGTON, Aug. 12 (Xinhua) -- NASA announced Friday the creation of a new directorate that will focus on both the International Space Station operations and human exploration beyond low earth orbit.The Human Exploration and Operations Mission Directorate combines the Space Operations and Exploration Systems mission directorates. While the transition and personnel assignments will take several weeks to finalize, the directorate already is supporting space station operations. It also will manage commercial crew and cargo developmental programs; construction of the Orion Multipurpose Crew Vehicle, a spacecraft designed to travel beyond low Earth orbit; development of a new heavy lift rocket, known as the Space Launch System; and other programs within the directorates."America is opening a bold new chapter in human space exploration," NASA Administrator Charles Bolden said in a statement. "By combining the resources of Space Operations and Exploration Systems, and creating the Human Exploration and Operations Mission Directorate, we are recommitting ourselves to American leadership in space for years to come."Associate Administrator Bill Gerstenmaier will head the new organization. He previously served as the associate administrator for Space Operations.

NEW YORK, Aug. 19 (Xinhua) -- U.S. crude oil price edged down on Friday, ending the week with a 3.65-percent loss, the fourth straight drop in the week.With absence of major macro-economic news, crude prices on Friday mainly followed the dollar's steps. As the dollar dipped to its historic low against the Japanese yen while dropping also against the euro, oil rallied for most of the trading session.But in the last trading hour, crude turned negative because the dollar bounced back from low and the U.S. stocks turned to red. The dollar index, tracking the greenback's performance against a basket of currencies, fell 0.4 percent.Crude prices fell sharply on Thursday as fears of a double-dip recession triggered sell-off of riskier assets. WTI dropped nearly 6 percent. On Friday, the markets seemed to start calming down. But for the week, it still posted a fall of 3.65 percent.Light, sweet crude for September delivery fell moderately 12 cents, or 0.15 percent to settle at 82.26 dollars a barrel on the New York Mercantile Exchange after trading from 79.17 to 83.55 dollars.But in London, Brent crude for October delivery gained 1.63 dollars, or 1.52 percent to close at 108.62 dollars a barrel. For this week, it gained 59 cents, or 0.55 percent.

WASHINGTON, July 27 (Xinhua) -- The solar-powered, Jupiter- bound Juno spacecraft was secured into place on top of its rocket Wednesday in preparation for launch next month, the U.S. National Aeronautics and Space Administration (NASA) announced.The launch period for Juno opens Aug. 5 and extends through Aug. 26. For an Aug. 5 liftoff, the launch window opens at 11:34 a.m. EDT (1534 GMT) and remains open through 12:43 EDT (1643 GMT).Juno will arrive at Jupiter in July 2016 and orbit its poles 33 times to learn more about the gas giant's interior, atmosphere and aurora."We're about to start our journey to Jupiter to unlock the secrets of the early solar system," said Scott Bolton, the mission 's principal investigator from the Southwest Research Institute in San Antonio. "After eight years of development, the spacecraft is ready for its important mission."

XICHANG, Sichuan, June 21 (Xinhua) -- China successfully launched a new communication satellite, the Zhongxing-10, from its Xichang Satellite Launch Center in southwest Sichuan Province on early Tuesday.The satellite, carried by a Long March-3B rocket carrier, blasted off from the center at 0:13 a.m., said a statement from the center.According to statistics from the control center, the satellite successfully separated from its carrier rocket and entered Earth's orbit as scheduled, 26 minutes after being launched.The Zhongxing-10 was designed and manufactured by the China Academy of Space Technology under the China Aerospace Science and Technology Corporation.The satellite will provide communication, broadcasting and data transmission services for users in China and the Asia-Pacific region. It will replace the Zhongxing-5B satellite, which was launched in 1998.The launch was the 138th mission for the Long March carrier rocket series.