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.

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.

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.

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.'

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

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.

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.

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.

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.

In a research by paleoceanographer Andre Bornemann of Leipzig University in Germany and his colleagues analyzed apparently unaltered Foraminifera picked from sediment core drilled from Demerara Rise beneath the western equatorial Atlantic. Following a classic technique, the researchers measured oxygen isotopes in the forams' shells. They found a sharp shift toward the heavier oxygen-18 isotope in both surface and bottom dwelling forams from 91.2 million years ago.