CO2 killing our coral reefs, say experts

London - The world's coral reefs are in danger of dying out in the next 20 years unless carbon emissions are cut drastically, warns a coalition of scientists led by Sir David Attenborough.

The delicate ecosystems, known as the “rainforests of the sea'', support huge amounts of marine life. But as oceans absorb CO2 they become more acidic, making it impossible for structures such as the Great Barrier Reef in Australia to survive.

Reefs are also at greater danger of bleaching as sea temperatures warm. Scientists gathered at the Royal Society in London to call for tougher target cuts in emissions. Sir David, who co-chaired the meeting, said the collapse of coral reefs meant the death of marine ecosystems. “We must do all that is necessary to protect the key components of the life of our planet as the consequences of decisions made now will likely be forever as far as humanity is concerned,'' he said. Open water absorbs around a third of the CO2 in the air. At present, the concentration of CO2 in the atmosphere is 387 parts per million (ppm).

Alex Rogers, the scientific director of the International Programme on the State of the Oceans, says the figure will reach 450ppm in the next 20 years if the world continues to burn fossil fuels at the present rate, and once that figure was reached the ocean would become too acidic for coral to survive. “The kitchen is on fire and it's spreading round the house. If we act quickly and decisively we may be able to put it out before the damage becomes irreversible,'' he said.

Coral reefs are living organisms that rely on calcium minerals, called aragonite, in the water to build and maintain their external skeletons. But when the oceans absorb CO2, it mixes with the seawater to make carbonic acid, reducing the aragonite levels. Mr Rogers said that once CO2 levels in the atmosphere reached the 600ppm mark, other organisms - such as plankton and sea snails - would start to die and whole marine ecosystems could collapse.

“Five hundred million people depend on coral reefs for livelihoods, food and culture,'' he said. “The economic implications of the loss of coral reefs are absolutely huge.'' Alongside other scientists from the Royal Society and Zoological Society of London, Mr Rogers wants world leaders to agree to much tougher targets to cut emissions as part of any climate change deal decided in Copenhagen at the end of this year.

“Essentially, coral reefs are on death row and Copenhagen is one of the last opportunities for a reprieve,'' he said. “If we carry on business as usual collapse is inevitable.'' - The New Zealand Herald

Source: http://www.iol.co.za/scitech/science/environment/co2-killing-our-coral-reefs-say-experts-1.1046850

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Shifting spring: Arctic plankton blooming up to 50 days earlier now

Climate researchers have long warned that the Arctic is particularly vulnerable to global warming. The dramatic shrinking of sea ice in areas circling the North Pole highlights those concerns.

A new report finds that the disappearing ice has apparently triggered another dramatic event - one that could disrupt the entire ecosystem of fish, shellfish, birds and marine mammals that thrive in the harsh northern climate.

Each summer, an explosion of tiny ocean-dwelling plants and algae, called phytoplankton, anchors the Arctic food web.

But these vital annual blooms of phytoplankton are now peaking up to 50 days earlier than they did 14 years ago, satellite data show.

"The ice is retreating earlier in the Arctic, and the phytoplankton blooms are also starting earlier," said study leader Mati Kahru, an oceanographer at the Scripps Institution of Oceanography in San Diego.

Drawing on observations from three American and European climate satellites, Kahru and his international team studied worldwide phytoplankton blooms from 1997 through 2009. The satellites can spot the blooms by their color, as billions of the tiny organisms turn huge swaths of the ocean green for a week or two.

The blooms peaked earlier and earlier in 11 percent of the areas where Kahru's team was able to collect good data. Kahru said the impacted zones cover roughly 1 million square kilometers, including portions of the Foxe Basin and the Baffin Sea, which belong to Canada, and the Kara Sea north of Russia.

In the late 1990s, phytoplankton blooms in these areas hit their peak in September, only after a summer's worth of relative warmth had melted the edges of the polar ice cap. But by 2009 the blooms' peaks had shifted to early July.

"The trend is obvious and significant, and in my mind there is no doubt it is related to the retreat of the ice," said Kahru, who published the work in the journal Global Change Biology.
"A 50-day shift is a big shift," said plankton researcher Michael Behrenfeld of Oregon State University, who was not involved in the study. "As the planet warms, the threat is that these changes seen closer to land may spread across the entire Arctic."

Ecologists worry that the early blooms could unravel the region's ecosystem and "lead to crashes of the food web," said William Sydeman, who studies ocean ecology as president of the nonprofit Farallon Institute in Petaluma, Calif.

When phytoplankton explode in population during the blooms, tiny animals called zooplankton - which include krill and other small crustaceans - likewise expand in number as they harvest the phytoplankton. Fish, shellfish and whales feed on the zooplankton, seabirds snatch the fish and shellfish, and polar bears and seals subsist on those species.

The timing of this sequential harvest is programmed into the reproductive cycles of many animals, Sydeman said. "It's all about when food is available." So the disrupted phytoplankton blooms could "have cascading effects up the food web all the way to marine mammals."
But the Arctic food web is poorly studied, and so any resulting decline in fish, seabirds and mammals will be difficult to spot.

As the Arctic Ocean north becomes less and less icy, commercial fisherman have begun eyeing these vast, untapped waters as an adjunct to the famously rich fishing grounds of the subarctic Bering Sea, west of Alaska.

But in 2009, the U.S. body overseeing fishing in the region, the North Pacific Fishery Management Council, banned commercial fishing in the Arctic Ocean, citing a lack of knowledge about how many - or even what kind - of fish live there.

"There are no catches authorized because we don't know enough about the fish populations there to set a quota," said Julie Speegle, a spokeswoman for the Alaska office of the National Marine Fisheries Service.

Last week, that service reported results from the first fish survey in 30 years of the Beaufort Sea, an arm of the Arctic Ocean north of Alaska. The survey found sizeable populations of several commercially valuable species, including pollock, Pacific cod and snow crab.

How these populations will respond to the ever-earlier plankton blooms is a big unknown, Sydeman said. But other research has shown that northern Atlantic cod populations crash when plankton blooms in that region shift in time.

Last week, the National Snow and Ice Data Center, in Boulder, Colo., reported that in February, Arctic sea ice covered a smaller area than ever seen in that month, tying with February 2005 as the most ice-free February since satellites began tracking Arctic ice in 1979.

The annual average Arctic sea ice coverage has decreased about 12 percent since then, a trend that appears to be accelerating, said Walt Meier, a research scientist at the center. Summer ice coverage has declined even more dramatically, he said, with the Arctic losing almost a third of its late-summer ice over the past 30 years.

Source: http://www.washingtonpost.com/wp-dyn/content/article/2011/03/06/AR2011030603417.html

By Brian Vastag
Washington Post Staff Writer
Monday, March 7, 2011

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South Florida water managers weigh costly consequences of sea level rise

For millions of South Floridians, life on a peninsula means melting icecaps in Greenland aren't just something for polar bears to worry about.

South Florida's coastal flood-control structures, counted on to protect low-lying communities from getting swamped, already are at risk from sea level rise due to climate change, according to scientists for the South Florida Water Management District.

In the coming months, the district's governing board will be asked to endorse more scientific studies and potentially costly flood-control construction projects aimed at preparing for the rising sea levels expected to come.

A district proposal outlined Tuesday calls for the agency over the next five years to buy more land for flood control, design improvements for 50-year-old drainage structures and start building pumps that could keep discharging stormwater out to the ocean even as sea levels continue to rise.

While politicians and world leaders debate the causes of climate change and how to respond, district scientists are adopting a "no-regrets strategy" to get ready, even if the worst-case scenarios don't come to pass.

"This is an issue of global importance that will have regional impacts," said Jayantha Obeysekera, who is leading the district's response to climate change and sea level rise. He briefed the district board Tuesday. "All aspects of water management would be impacted."

An increase in carbon dioxide and other greenhouse gases in the Earth's atmosphere are trapping more of the sun's heat, leading to climate change — blamed for higher temperatures that are projected to increase the rate of sea level rise.

Manmade pollution produces more of those heat-trapping greenhouse gases.

Sea ice, glaciers and snow cover around the world all are shrinking as temperatures rise, Obeysekera said.

The district is anticipating sea levels to climb 5 to 20 inches during the next 50 years.

High water levels at times already are creating problems for some of the floodgates, spillways and drainage canals that protect South Florida from flooding.

South Florida now has periods of extreme high tides, when water levels rise higher than the point where stormwater from coastal drainage canals normally gets dumped into the sea.

When that happens, floodgates stay closed, increasing the flood risk if those drainage canals overflow. That would worsen if sea levels rise.

Overwhelmed coastal drainage canals would have a "domino effect" on the rest of South Florida's drainage system, according to Carol Wehle, water district executive director.

If there's insufficient room for water in drainage canals, then there's not enough room for water coming in from community drainage systems. Those community systems help keep inland neighborhoods dry.

"The capacity … of the system is going to be negatively impacted by sea level rise," Wehle said.

The district has so far identified 28 flood-control structures along the southeast coast and six along the west coast most at risk to rising sea levels.

The first three are the S27, S28 and S29 facilities in northern Miami-Dade County.

New pumps are proposed to push stormwater into the ocean while keeping floodgates closed to hold back the elevated seas.

Cost remains a hurdle to getting that done. The current proposal would begin work by 2015. Each one cost "tens of millions of dollars," Obeysekera said.

Another threat from rising sea levels is more saltwater seeping in underground and contaminating drinking water supplies. South Florida has coastal well fields that through the years have had to shut down or reduce pumping due to saltwater intrusion.

Water utilities in Lake Worth, Hallandale Beach and Lantana have been among the most at risk of saltwater intrusion.

If that continues, it means increased costs to find new drinking water supplies or to switch to more costly water treatment processes — both of which would mean higher water bills for South Florida residents.

In addition, the Everglades can expect to suffer from an influx of saltwater.

Sea level rise is expected to affect the southern end of the Everglades by increasing coastal erosion, reducing mangrove forests, pushing migrating wading birds northward, increasing peat collapse and raising salinity levels in freshwater marshes that could result in fish kills and loss of wildlife habitat.

The state and federal government are in the midst of investing billions of dollars in Everglades restoration. Some contend that those restoration projects should be reconsidered due to the expected damage from sea level rise.

Others counter that restoring more of the stormwater flows that once naturally reached the Everglades will counterbalance the effects of climate change.

"It's critical to act fast enough," said Jane Graham of Audubon of Florida. "Fight water with water."

Computer modeling is being used to try to chart which areas are most at risk of flooding from sea level rise.

During the coming year, the district plans to further identify water-management projects affected by sea level rise; complete reports on trends in sea-level rise and climate change; and finish an analysis of the saltwater-intrusion monitoring system.

The sea level rise is not really in dispute, said district board member Jerry Montgomery, pointing to melting glaciers and ice sheets from Greenland to Antarctica. The question, Montgomery said, is the rate of rise and how much it will affect South Florida.

"It is clearly melting and it is clearly melting at a faster rate," Montgomery said.

Andy Reid can be reached at abreid@SunSentinel.com or 561-228-5504.

Source: http://www.sun-sentinel.com/news/palm-beach/fl-sea-level-rise-south-florida-20101109,0,5651053,full.story

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Acidifying Oceans Dramatically Stunt Growth of Already Threatened Shellfish, Research Finds

ScienceDaily — New research shows that global warming and its effects -- in particular, ocean acidification have descended upon shellfish reefs, particularly those formed by the Olympia oyster.

More than one-third of the world's human-caused carbon dioxide emissions have entered the oceans, according to Brian Gaylord, a biological oceanographer at the Bodega Marine Laboratory of the University of California at Davis.

"Similar to what happens in carbonated soda," says Gaylord, "increasing carbon dioxide in seawater makes it more acidic."

Even with small changes in acidity, seawater becomes corrosive to the shells of aquatic organisms.

That's not good news for most marine life, especially for oysters.

Gaylord is investigating the consequences of this increasing ocean acidity on the growth of larval and juvenile Olympia oysters native to the U.S. West Coast.

"Such early life stages can be extremely sensitive to environmental stresses like ocean acidification," says Gaylord.

"These stages operate as bottlenecks that drive overall population numbers. If larval and juvenile Olympia oysters decline as a result of an acidifying ocean, what does that mean for the species as a whole?"

Likely nothing good, he and colleagues say.

"Changes now happening in the ocean's chemistry are expected to continue far into the foreseeable future," says David Garrison, director of the National Science Foundation (NSF)'s biological oceanography program, which funds Gaylord's research. "They may have myriad effects on marine animals."

Gaylord conducted experiments on larvae and juveniles produced by adult oysters in Tomales Bay, California. Adults were collected in the bay, then held at the Bodega Marine Laboratory until they released larvae.

In the lab, the free-swimming larvae were reared into early juvenile life.

Carbon dioxide concentrations in laboratory seawater were controlled to match present-day conditions in the oceans, 380 parts per million (ppm), as well as two carbon dioxide scenarios projected to occur by the year 2100 (540 and 970 ppm).

Mid-way through the larval phase at day nine, oysters in the high carbon dioxide treatment had shells that were 16 percent smaller than those reared in control, or ambient, conditions.

These effects continued through the time the larval oysters settled onto hard substrate at day 12. Shell size was seven percent smaller for oysters in the 970 ppm treatment than in the control group.

By a week later, the effects were dramatically magnified. The bottom-dwelling juveniles in the 970 ppm treatment had grown 41 percent less than juveniles under control conditions.

The consequences persisted, even after the juveniles from all treatments had been returned to present-day conditions.

"One and a half months after being transferred back to normal seawater," says Gaylord, "juveniles that had come from the high carbon dioxide environment were still 28 percent smaller than oysters reared for the entire experiment in control conditions."

The results strongly suggest that the effects of ocean acidification on oyster larvae persist well into the juvenile phase, he says, with potential consequences for oyster populations.

"If similar impacts happen to species beyond the Olympia oyster, there could be repercussions for oysters around the world."

Globally, 85 percent of shellfish reefs have been lost, making oyster reefs one of the most severely threatened marine habitats on the planet.

"Shellfish reefs in some places are at less than 10 percent of their former abundance," says Garrison. "Oysters have gone extinct in many areas, especially in North America, Australia and Europe."

Just as coral reefs are critical to tropical marine habitats, shellfish like oysters are the ecosystem engineers of bays and estuaries, creating dwelling places for countless plants and animals that find refuge in their three-dimensional structure.

The surface area of an oyster bed across its dips and folds and crevices may be 50 times greater than that of an equally extensive flat mud bottom.

Shellfish reefs also provide important services to people by filtering water, and serving as natural coastal buffers from boat wakes, sea-level rise and storms.

Oysters have supported civilization for millennia, from the ancient Romans to railroad workers in California in the 1880s. In the 1870s, eastern oyster reefs extended for miles along the James River in Chesapeake Bay. By the 1940s, they had largely disappeared.

"It's unclear whether we will ever be able to return to that by-gone era," says Gaylord. "The constellation of environmental and other pressures on oysters--including the consequences of ocean acidification--places them at grave risk."

Gaylord and colleagues presented early results of their research at the Ocean Sciences Meeting in Portland, Oregon, in February. They plan to publish a paper with updated findings later this year.

Source: http://www.sciencedaily.com/releases/2010/04/100420152841.htm

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'Black Box' Plankton Found to Have Huge Role in Ocean Carbon Fixation

ScienceDaily — Scientists at the University of Warwick and the National Oceanography Centre in Southampton have opened "the black box" of eukaryotic phytoplankton and discovered that they actually account for almost half the ocean's carbon fixation by phytoplankton.

Carbon fixation by phytoplankton in the open ocean plays a key role in the global carbon cycle but is not fully understood. Until now researchers believed that cyanobacteria overwhelmingly accounted for phytoplankton's role in carbon fixation in the open ocean. But now scientists at the University of Warwick and the National Oceanography Centre in Southampton have opened "the black box" of eukaryotic phytoplankton and discovered that they actually account for almost half the ocean's carbon fixation by phytoplankton.

Blue-green algae, or cyanobacteria, grow in vast numbers in the sunlit surface waters of the oceans, the photic zone. They use sunlight to 'fix' carbon by converting carbon dioxide into sugars and other organic compounds through photosynthesis.

Cyanobacteria belong to the 'picophytoplankton', the tiniest phytoplankton. Until now they have been thought to dominate carbon fixation in the open ocean, with species belonging to the genera Prochlorococcus and Synechococcus being particularly abundant.

Like all bacteria, cyanobacteria are prokaryotes, distinguished from eukaryotes by the absence of a cell nucleus. However, although much less abundant than cyanobacteria, the photic zone also has a high biomass of small eukaryotic phytoplankton capable of carbon fixation.

"The eukaryotic phytoplankton community has long been a 'black box' in terms of its composition as well as contribution to carbon fixation," says Professor Dave Scanlan of the University of Warwick; "Determining how much carbon different groups fix into biomass is required for a full understanding of the Earth's carbon cycle," adds Professor Mikhail Zubkov of the National Oceanography Centre.

In research, published April 15 in the Journal of the International Society for Microbial Ecology, the scientists report how they measured carbon fixation by dominant phytoplankton groups in the subtropical and tropical northeast Atlantic Ocean, using samples collected from surface waters during a research cruise aboard the Royal Research Ship Discovery.

They discovered that eukaryotic phytoplankton actually fix significant amounts of carbon, contributing up to 44% of the total, despite being considerably less abundant than cyanobacteria. "This is most likely because eukaryotic phytoplankton cells, although small, are bigger than cyanobacteria, allowing them to assimilate more fixed carbon," says Zubkov.

Two groups of eukaryotes were distinguished, 'EukA' cells being more abundant but smaller than 'EukB' cells. Molecular techniques revealed that EukB largely comprised photosynthetic organisms called prymnesiophytes, most of which have never been cultured in the laboratory. Many of these are probably previously unknown species.

"Prymnesiophytes accounted for up to 38 per cent of total primary production in the subtropical and tropical northeast Atlantic Ocean," says Scanlan: "This suggests that they play a key role in oceanic carbon fixation, but this needs to be confirmed by widespread sampling from the world's oceans."

Zubkov recently showed that small eukaryotic phytoplankton can obtain carbon by feeding on bacteria, supplementing carbon fixed through photosynthesis.

It is likely that some of the organic carbon of prymnesiophytes and other eukaryotic phytoplankton is eventually exported from the photic zone to the deep ocean, rather than being returned to the atmosphere in the form of carbon dioxide.

"Given their clear importance, it is crucial that we now go on to understand the factors controlling growth of small eukaryotes in the oceans," concludes Scanlan.

Source: http://www.sciencedaily.com/releases/2010/04/100415085344.htm

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