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Oceans and Seas

  • Human shadows on world's oceans

    Scientists Are Building First Worldwide Portrait Of Human Impact That Has Left Just 4% Of The Seas Pristine In 1980, after college, I joined the crew of a sailboat partway through a circumnavigation of the globe. Becalmed and roasting one day during a 21-day crossing of the western Indian Ocean, several of us dived over the side. Within a few swimming strokes, the bobbing hull seemed a toy over my shoulder as I glanced back through my diving mask. Below me, my shadow and the boat's dwindled to the vanishing point in the two-mile-deep water. Human activity seemed nothing when set against the sea itself. Just a few weeks later, on an uninhabited island in a remote part of the Red Sea, I was proved wrong. The shore above the tide line was covered with old light bulbs, apparently tossed from the endless parade of ships over the years. Now scientists are building the first worldwide portrait of such dispersed human impacts on the oceans, revealing a planet-spanning mix of depleted resources, degraded ecosystems and disruptive biological blending as species are moved around the globe by accident and intent. A paper in the February 15 issue of the journal Science is the first effort to map 17 kinds of human ocean impacts like organic pollution, including agricultural runoff and sewage; damage from bottomscraping trawls; and intensive traditional fishing along coral reefs. About 40% of ocean areas are strongly affected, and just 4% pristine, according to the review. Polar seas are in the pristine category, but poised for change. Some human impacts are familiar, like damage to coral reefs and mangrove forests through direct actions like construction and subtler ones like the loss of certain fish that shape ecosystems. Others were a surprise, said Benjamin S Halpern, the lead author and a scientist at the National Center for Ecological Analysis and Synthesis in Santa Barbara, California. He said continental shelves and slopes proved to be the most heavily affected areas, particularly along densely populated coasts. The most widespread human fingerprint is a slow drop in the pH of surface waters around the world as a portion of the billions of tons of carbon dioxide added to the atmosphere from fuel and forest burning each year is absorbed in water, where it forms carbonic acid. That progressive shift in ocean chemistry could eventually disrupt shell-forming plankton and reef-building species, particularly where other impacts, including rising temperatures from human-caused global warming, create simultaneous stresses, many marine biologists say. "I study this stuff all the time and didn't expect the impacts to be as pervasive as we found,' Halpern said. The review provides a baseline necessary for tracking further shifts, he said. It also identifies some unanticipated trouble spots, similar to terrestrial biodiversity "hot spots' that environmental groups have identified over the years. NYT NEWS SERVICE

  • Human activities affecting oceans

    Human activities are affecting every square mile of the world's oceans, according to a study by a team of American, British and Canadian researchers who mapped the severity of the effects from pole to pole. The analysis of 17 global data sets, led by Benjamin S. Halpern of the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif., illustrates the extent to which humans are reshaping the seas through overfishing, air pollution and commercial shipping. The study, published in the journal Science, examines the impacts on nearly two dozen marine ecosystems, including coral reefs and continental shelves. "For the first time we can see where some of the most threatened marine ecosystems are and what might be degrading them,' said Elizabeth Selig, a Ph.D. candidate at the University of North Carolina at Chapel Hill and a co-author, in a statement. "This information enables us to tailor strategies and set priorities for ecosystem management. And it shows that while local efforts are important, we also need to be thinking about global solutions.' The team of scientists analysed factors, including warming ocean temperatures due to greenhouse gas emissions, nutrient runoff and fishing. They found that the areas under the most stress included are "the North and Norwegian seas, South and East China seas, Eastern Caribbean, North American eastern seaboard, Mediterranean, Persian Gulf, Bering Sea, and the waters around Sri Lanka.' Some marine ecosystems are under acute pressure, the scientists concluded, including sea mounts, mangrove swamps, seagrass and coral reefs. Almost half of all coral reefs, they wrote, "experience medium high to very high impact' from humans. Overall, rising ocean temperatures represent the biggest threat to marine ecosystems.

  • Ocean CO2 studies look beyond coral

    One million tons of atmospheric carbon dioxide are dissolved into the oceans every hour, a process that helps maintain the Earth's delicate carbon balance. But CO2 also makes seawater more acidic, and too much of it can wreak havoc on a marine species.

  • King penguin population threatened by Southern Ocean warming

    Seabirds are sensitive indicators of changes in marine ecosystems and might integrate and/or amplify the effects of climate forcing on lower levels in food chains. Current knowledge on the impact of climate changes on penguins is primarily based on Antarctic birds identified by using flipper bands.

  • Human hand decisive for oceans

    In one of the most comprehensive looks yet at the oceans, researchers say that humans have "strongly' fouled 41 per cent of the high seas with everything from storm water runoff to shipping waste and that only small polar regions are still untouched. "Almost half of the oceans are in a fairly degraded state, based on what we found,' said Benjamin Halpern, the report's lead author and a marine biologist at the California-based National Centre for Ecological Analysis and Synthesis. "There isn't a spot on the planet that hasn't been touched by humans.' The report, being published Friday in the journal Science and presented at a scientific conference this week in Boston, is designed to summarise how humans are affecting the 70 per cent of the planet covered by the seas. "You just can't manage fisheries alone or try to just manage nutrient runoff or invasive species by themselves. You have to think of them in a more comprehensive context,' said Donald F. Boesch, a professor of marine science and president of the University of Maryland Centre for Environmental Science. The international team of 19 researchers looked at effects from 17 human activities, including commercial fishing, runoff from development, invasive species, industrial pollution, oil rigs and climate change. Their sources included satellite imagery, UN reports on fisheries harvests, estimates of commercial shipping wastes and runoff from pesticide use. "The oceans are in trouble, in a lot of areas and in a lot of ways,' said Andrew Rosenberg, a professor of natural resources at the University of New Hampshire who reviewed the study. Only 3.7 per cent of the oceans have seen little or no effect from human activity and they lie near the North and South poles, the researchers say. The most polluted areas are along the Atlantic's eastern seaboard, as well as in the North Sea, Caribbean, Red Sea, Bering Sea, the Persian Gulf and the China seas. "Hopefully, this is a wakeup call showing what our impacts are on the oceans and what can be done to minimise them,' Halpern said. There have been previous alarms. A $5-million report by the Pew Ocean Commission in 2003 called for restoring coastline ecosystems, improving the way fisheries are managed and cracking down on sources of pollution. But experts say Halpern's report goes further. "This changes how we view the oceans by showing how widely scattered our impacts are,' said Boris Worm, a marine biologist at Dalhousie University in Halifax, Canada. Worm was co-author of a report in 2003 that predicted a collapse of the world's fisheries by mid-century if human effects continue at their current pace. The most severely troubled waters lie within dozens of miles of most coastlines. It is there that effects from land and ocean-based activities show up, such as the depletion of fish stocks from commercial fishing and sediment runoff from coastal development. Industrial fishing fleets equipped with sonar and global positioning systems have fished the seas to the point that about 90 per cent of the worldwide stocks of tuna, cod and other large fish have disappeared, experts say. To help address the problem, people should be careful to eat fish harvested with sustainable, environmentally conscious methods and try to reduce greenhouse gas emissions by driving smaller cars, Halpern said. They also should avoid fertilisers and pesticides, he said. "There are things people can do.'

  • Lankan waters heavily affected by pollution

    The waters around Sri Lanka are among the most heavily damaged and polluted ocean regions in the world, a study has revealed. The research by a team of American, British and Canadian researchers was published in yesterday's edition of Science. Activities like water and air pollution, overfishing, commercial shipping or greenhouse gas emission are continually damaging the planet and there is no sign that they will ever stop. Apparently, the most affected areas are "the North and Norwegian seas, South and East China seas, Eastern Caribbean, North American eastern seaboard, Mediterranean, Persian Gulf, Bering Sea, and the waters around Sri Lanka, the study said. The survey, analysing all 17 activities through which humans impact the oceans, and their conclusion was that every square mile of the ocean has been damaged in some way. The researchers have designed a map that emphasizes and explains the results of their study. The map was released at the annual meeting of the American Association for the Advancement of Science in Boston and published in yesteday's edition of the journal Science, the Associated Press reported. "Our results show that when these and other individual impacts are summed up, the big picture looks much worse than I imagine most people expected. It was certainly a surprise to me,' said lead author Ben Halpern, an assistant research scientist at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara, according to the Associated Press. The oceans around the polar areas are the least impacted, but scientists predict they will be damaged more and more in the following years, as long as the global warming continues. "There were two things we didn't anticipate,' Halpern added in the telephone interview. "Every single spot in the oceans was affected by at least one human activity ... we figured there'd be places people just hadn't gotten to yet.' Some good news is that, in the Congress yesterday, the House voted the approval of $454 million for ocean exploration programmes and studies over the next seven years, at the National Geographic and Atmospheric Administration. Ben Halpern still has hope that things can be improved. "There are some areas in fairly good condition. They are small and scattered, but have fairly low impact. That suggests that with effort from all of us, we can try to protect these patches and use them as a guideline for what we'd like the rest of the ocean to start looking like,' he stated. e-News

  • Global warming may not have caused sluggish Atlantic

    Judging the effect of climate change on ocean currents could take longer than we thought. The circulation of warm water in the North Atlantic is suspected to be slowing, and the worry is that global warming is to blame.

  • A global map of human impact on marine ecosystems

    The management and conservation of the world's oceans require synthesis of spatial data on the distribution and intensity of human activities and the overlap of their impacts on marine ecosystems.

  • In dead water: merging of climate change with pollution, over-harvest, and infestations in the world's fishing grounds

    Climate change is presenting a further and wide-ranging challenge with new and emerging threats to the sustainability and productivity of a key economic and environmental resource. This report attempts to focus the numerous impacts on the marine environment in order to assess how multiple stresses including climate change might shape the marine world over the coming years and decades.

  • Isotopic evidence for glaciation during the Cretaceous supergreenhouse

    The Turonian (93.5 to 89.3 million years ago) was one of the warmest periods of the Phanerozoic eon. It has been argued that there may have been several stages of continental ice growth during the period, reflected in both erosional surfaces and geochemical records associated with possible glaciation-induced sea-level falls.

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