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Hunter Cutting

Ocean Ecosystems Transforming Due to Climate Change - 0 views

  • Global climate change is fundamentally disrupting marine ecosystems, especially in the polar oceans, according to two new reviews of scientific research released Thursday in the journal Science.
  • Changes in temperature, ocean acidity and volume are affecting species from phytoplankton — the microscopic marine plants at base of the food chain — to polar bears, which may lose 68 percent of their summer habitat by 2100. "Climate change is affecting an enormously wide range of physical and biological aspects of the ocean," said John Bruno, a University of North Carolina marine ecologist and co-author of one of the reviews. "Once you start tweaking temperature, everything changes." Photosynthesis by phytoplankton is down six percent since the 1980s, and the organisms themselves are getting smaller thanks to warmer temperatures, the review noted.
  • Less plankton means less food for fish, which in turn means less seafood for human consumption. Phytoplankton also absorb carbon dioxide from the air and sequester it at the seafloor when they die and sink to the bottom of the ocean. Fewer phytoplankton could mean more human carbon dioxide emissions stay in the atmosphere, Bruno said, further exacerbating the climate change problem.
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  • The "canary in the coalmine" for all of these shifts is the polar oceans, said Oscar Schofield, an oceanographer at Rutgers University in Newark, New Jersey and a co-author of the second review, which focuses on changes at the West Antarctic Peninsula. There, the authors found, temperatures have increased by 6 degrees Celsius in the past 50 years, more than five times the average change worldwide. Phytoplankton blooms are down 12 percent overall. Krill populations — important food for whales, penguins, fish and other large animals — are plummeting, with jellyfish-like organisms called salps, which don't make as good a meal, taking their place.
  • Above the surface, the polar Adélie penguin population has gone from tens of thousands of breeding pairs to just a few thousand, Schofield said. Temperate species of penguin like the Chinstrap and Gintoo are moving into the Adélie’s old turf. Particularly shocking, Schofield said, is how rapidly these changes are occurring. "It's not like it's happening over hundreds of years," he said. "It's happening over decades."
Hunter Cutting

Plankton, base of ocean food chain, in big decline due to warming - 0 views

  • Plankton, base of ocean food web, in big decline
  • Half a million datapoints dating to 1899 show that plant plankton levels in nearly all of the world's oceans started to drop in the 1950s. The biggest changes are in the Arctic, southern and equatorial Atlantic and equatorial Pacific oceans. Only the Indian Ocean is not showing a decline. The study's authors said it's too early to say that plant plankton is on the verge of vanishing. Virginia Burkett, the chief climate change scientist for U.S. Geological Survey, said the plankton numbers are worrisome and show problems that can't be seen just by watching bigger more charismatic species like dolphins or whales. "These tiny species are indicating that large-scale changes in the ocean are affecting the primary productivity of the planet," said Burkett, who wasn't involved in the study.
  • Despite their tiny size, plant plankton found in the world's oceans are crucial to much of life on Earth. They are the foundation of the bountiful marine food web, produce half the world's oxygen and suck up harmful carbon dioxide. And they are declining sharply. Worldwide phytoplankton levels are down 40 percent since the 1950s, according to a study published Wednesday in the journal Nature. The likely cause is global warming, which makes it hard for the plant plankton to get vital nutrients, researchers say. The numbers are both staggering and disturbing, say the Canadian scientists who did the study and a top U.S. government scientist. "It's concerning because phytoplankton is the basic currency for everything going on in the ocean," said Dalhousie University biology professor Boris Worm, a study co-author. "It's almost like a recession ... that has been going on for decades."
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  • When plant plankton plummet — like they do during El Nino climate cycles_ sea birds and marine mammals starve and die in huge numbers, experts said.
  • Worm said when the surface of the ocean gets warmer, the warm water at the top doesn't mix as easily with the cooler water below. That makes it tougher for the plant plankton which are light and often live near the ocean surface to get nutrients in deeper, cooler water. It also matches other global warming trends, with the biggest effects at the poles and around the equator.
Hunter Cutting

Global warming driving 40 per cent decline in the ocean's phytoplankton - 0 views

  • The dead sea: Global warming blamed for 40 per cent decline in the ocean's phytoplankton Microscopic life crucial to the marine food chain is dying out. The consequences could be catastrophic
  • The microscopic plants that support all life in the oceans are dying off at a dramatic rate, according to a study that has documented for the first time a disturbing and unprecedented change at the base of the marine food web. Scientists have discovered that the phytoplankton of the oceans has declined by about 40 per cent over the past century, with much of the loss occurring since the 1950s. They believe the change is linked with rising sea temperatures and global warming.
  • If the findings are confirmed by further studies it will represent the single biggest change to the global biosphere in modern times, even bigger than the destruction of the tropical rainforests and coral reefs, the scientists said yesterday.
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  • Phytoplankton are microscopic marine organisms capable of photosynthesis, just like terrestrial plants. They float in the upper layers of the oceans, provide much of the oxygen we breathe and account for about half of the total organic matter on Earth. A 40 per cent decline would represent a massive change to the global biosphere."If this holds up, something really serious is underway and has been underway for decades. I've been trying to think of a biological change that's bigger than this and I can't think of one," said marine biologist Boris Worm of Canada's Dalhousie University in Halifax, Nova Scotia. He said: "If real, it means that the marine ecosystem today looks very different to what it was a few decades ago and a lot of this change is happening way out in the open, blue ocean where we cannot see it. I'm concerned about this finding."The researchers studied phytoplankton records going back to 1899 when the measure of how much of the green chlorophyll pigment of phytoplankton was present in the upper ocean was monitored regularly. The scientists analysed about half a million measurements taken over the past century in 10 ocean regions, as well as measurements recorded by satellite.They found that phytoplankton had declined significantly in all but two of the ocean regions at an average global rate of about 1 per cent per year, most of which since the mid 20th Century. They found that this decline correlated with a corresponding rise in sea-surface temperatures – although they cannot prove that warmer oceans caused the decline.The study, published in the journal Nature, is the first analysis of its kind and deliberately used data gathered over such a long period of time to eliminate the sort of natural fluctuations in phytoplankton that are known to occur from one decade to the next due to normal oscillations in ocean temperatures, Dr Worm said. "Phytoplankton are a critical part of our planetary life support system. They produce half of the oxygen we breathe, draw down surface CO2 and ultimately support all of our fishes." he said.But some scientists have warned that the Dalhousie University study may not present a realistic picture of the true state of marine plantlife given that phytoplankton is subject to wide, natural fluctuations."Its an important observation and it's consistent with other observations, but the overall trend can be overinterpreted because of the masking effect of natural variations," said Manuel Barange of the Plymouth Marine Laboratory and a phytoplankton expert.
  • However, the Dalhousie scientists behind the three-year study said they have taken the natural oscillations of ocean temperatures into account and the overall conclusion of a 40 per cent decline in phytoplankton over the past century still holds true. "Phytoplankton are the basis of life in the oceans and are essential in maintaining the health of the oceans so we should be concerned about its decline."It's a very robust finding and we're very confident of it," said Daniel Boyce, the lead author of the study."Phytoplankton is the fuel on which marine ecosystems run. A decline of phytoplankton affects everything up the food chain, including humans," Dr Boyce said.
  • Phytoplankton is affected by the amount of nutrients the well up from the bottom of the oceans. In the North Atlantic phytoplankton "blooms" naturally in spring and autumn when ocean storms bring nutrients to the surface. One effect of rising sea temperatures has been to make the water column of some regions nearer the equator more stratified, with warmer water sitting on colder layers of water, making it more difficult for nutrients to reach the phytoplankton at the sea surface.Warmer seas in tropical regions are also known to have a direct effect on limiting the growth of phytoplankton.
Hunter Cutting

Rhode Island floods prompt cold water phytoplankton surge - 0 views

  • Torrential rains last month in Rhode Island led to widespread flooding, causing millions of dollars in property damage and leaving thousands homeless. The floodwaters also overwhelmed water treatment plants, spilling vast amounts of raw sewage into the rivers and streams that flow into Narragansett Bay. It sounds like the makings of an environmental nightmare, but in fact it’s just the opposite. To scientists’ delight, the sewage-laden floodwaters have caused a well-timed bloom of phytoplankton, the microscopic creatures that form the foundation of marine food chains. With more food available for fish, clams and other sea creatures, the bay’s fisheries industry is expected to benefit. The timing of the rains was fortuitous. In decades past, Narragansett Bay typically experienced a late winter/early spring algal bloom that fed creatures up and down the water column. But in recent years, the waters of Narragansett Bay have warmed greatly, interrupting this seasonal event. In particular, bottom-feeding fish like the flounder have suffered dramatic declines. The surge of freshwater and nutrient-rich sewage this spring, however, is mimicking the conditions of years past. Mark Berman, an oceanographer with the National Marine Fisheries Service, said the flood seemed to have sent the bay back to its  normal state.
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    In Fearsome Floods, a Dividend - Green Blog - NYTimes.com
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