Corals Partner Up With Heat-Resistant Algae

Corals around the world, already threatened by pollution, destructive fishing practices and other problems, are also widely regarded as among the ecosystems likely to be first — and most — threatened with destruction as earth’s climate warms.

But there is reason to hope, researchers are reporting. The scientists, from Penn State University and elsewhere, have produced new evidence that some algae that live in partnership with corals are resilient to higher ocean temperatures. One species, Symbiodinium trenchi, is particularly abundant – “a generalist organism,” the researchers call it, able to live with a variety of coral hosts.

Corals and algae live together in what scientists call a symbiotic relationship. Coral polyps shelter the algae and as the tiny plants photosynthesize they produce sugars the corals rely on for food. When water warms, though, reefs’ brown or green algae partners die, leaving the reefs white. These so-called bleaching events have become more common as ocean waters warm.

The new research focused on corals in the Andaman Sea, in the northeastern Indian Ocean, but other scientists have made similar algae findings in the Caribbean Sea and the Pacific Ocean.

Heat-resistant algae are not enough to save corals, most researchers agree, but their presence may buy time for some reefs. Other researchers have suggested that unusual periods of warm water may allow heat-resilient algae to proliferate, to the long term benefit of corals.

Unfortunately, though, heat-resilient algae do not necessarily occur in corals everywhere. And it is not clear whether importing the algae to threatened reefs would work to save them. “You never know what the effects might be of introducing an organism into an ecosystem in which it is not well established,” Todd LaJeunesse, one of the Penn State researchers said in a statement reporting the new work.

Also, while the algae findings offer a glimmer of hope, there remain plenty of reasons to worry. Perhaps chief among them is the fact that as ocean waters absorb carbon dioxide they become more acidic, threatening the coral skeletons.

source: http://dotearth.blogs.nytimes.com/2010/02/18/corals-partner-up-with-heat-resistant-algae/

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Toxic algae could be the next big threat

BY LES BLUMENTHAL
McClatchy Newspapers

WASHINGTON -- With a new theory surfacing that toxic algae rather than asteroids killed the dinosaurs, scientists are still trying to unravel the mystery of what caused a massive algae bloom off the Northwest Coast that left thousands of seabirds dead and may have sickened some surfers and kayakers.

The bloom, which stretches roughly 300 miles from Newport, Ore., north to the Canadian border, still persists, though it's a shadow of its September and October peak.

Whipped by waves and storms, the microscopic phytoplankton, which had turned the ocean a rust color, broke apart, releasing toxins and creating meringue-like foam that coated the feathers of birds like spilled oil. Up to 10,000 birds died of hypothermia in September, and researchers are still trying to come up with a count for October.

Researchers are also checking reports that surfers and kayakers who came in contact with the foam may have suffered cold-like symptoms, including temporary loss of smell and taste. The toxins also may have become aerosolized and affected beachcombers. In another strange twist, pathologists performing necropsies found that some of the birds lacked normal bacteria in their stomachs and other internal organs.

"It's definitely a warning sign of something," said Julia Parrish, a professor of aquatic and fishery sciences at the University of Washington. "We don't know what."

Blooms of the single-cell, saltwater algae species known as Akashiwo sanguinea have been found in Puget Sound, the Chesapeake Bay and elsewhere around the world. The bloom off the Northwest coast, however, is huge compared with others. At its height, there were 1.5 million algae cells per quart of water. The bloom was up to 65 feet deep and miles wide.

In only one other instance - a smaller bloom in 2007 in California's Monterey Bay - have the cells broken apart to create a toxic froth. And this particular specie of algae usually likes warmer water than that found off the Northwest Coast.

No one is sure what ignited the bloom. Some scientists think it could be caused by climate change, which has raised ocean temperatures and made the water more acidic - both conditions could favor this algae species. Others say it could be the result of such weather conditions as El Nino or the Pacific decadel oscillation, a long-lived El Nino-like pattern of Pacific climate variability.

The bloom could have been fed by nutrients washed down the Columbia River from farms in eastern Washington and Oregon, or from an ocean condition known as upwelling, where cold water rich with nutrients is pushed toward the surface by the wind.

Or, it could just be the rhythms of the ocean, which scientists are just starting to understand.

"The ocean does have a natural pulse," said Vera Trainer, a Seattle-based research oceanographer for the National Oceanic and Atmospheric Administration. "Is this part of the pulse or is this something different? We want to find out. But some of this is very unusual. We are looking at this very intensely."

Even as Trainer, Parrish and others study the bloom off the Northwest Coast, one of the scientists who developed the theory linking toxic algae to mass extinctions said it fit in with the research he and his partner were working on.

"That's exactly what we are talking about," said John Rodgers, an ecotoxicologist at Clemson University in South Carolina, who along with James Castle, a geologist at Clemson, developed the killer algae theory.

Rodgers was on the road last week in the Midwest, collecting samples of algae to analyze back in his lab. He said he and Castle have found ancient deposits of blue-green algae that produce toxins and deplete oxygen that coincide with five mass extinctions millions of years ago. Though he said algae may not have been the only cause for the extinctions, he said it was a major factor.

The blue-green algae was freshwater algae in ponds, lakes and rivers that could have been ingested by prehistoric animals. The toxins also may have been absorbed by plants that were later eaten by animals or become airborne and breathed in by animals.

"They certainly didn't die on the same day or week," Rodgers said. "This happened over hundreds of years."

Even though there are thousands of species of algae, only several hundred produce toxins, he said.

Though the bloom off the Northwest coast is in salt water rather than fresh water, Rodgers said such blooms were well worth keeping an eye on.

"They are changing, expanding their ranges into places never seen before and in densities never seen before," Rodgers said. "It's hard to ignore, and as the data grows, we are becoming more and more convinced."

Rodgers said his theory has been peer reviewed and is gaining acceptance among scientists.

Current climate conditions are becoming strikingly similar to those that existed during the time of the mass extinctions, he said.

In a paper published in March in the journal Environment Geosciences, Rodgers and Castle wrote that their findings "gives us cause for concern and underscores the importance of careful and strategic monitoring as we move into an era of global climate change."

Scientists studying the bloom off the Northwest are wary when asked about Rodgers' and Castle's theory.

"I would be cautious about it," Trainer said.

Raphael Kudela, a toxic algae expert and ocean sciences professor at the University of California at Santa Cruz, thinks algae blooms such as those off the Northwest Coast are becoming more frequent.

"It is consistent with climate change," Kudela said, adding that a bloom like this in the chilly waters of the Northwest was "very unusual."

As for the killer algae theory, Kudela said, "People who study harmful algae don't dismiss it. But it can't be proved."

Parrish doesn't quite know what to make of the theory that algae killed dinosaurs. Back when life was just starting, she said, algae and other single-cell organisms excreted oxygen that created the atmosphere.

"The claim algae had a humongous effect on the atmosphere is correct," Parrish said. "Whether it caused mass extinctions, I don't know."

Source: http://www.miamiherald.com/news/politics/AP/v-fullstory/story/1379798.html

Large 2009 Gulf Of Mexico 'Dead Zone' Predicted

ScienceDaily — University of Michigan aquatic ecologist Donald Scavia and his colleagues say this year's Gulf of Mexico "dead zone" could be one of the largest on record, continuing a decades-long trend that threatens the health of a half-billion-dollar fishery.

The scientists' latest forecast, released June 18, calls for a Gulf dead zone of between 7,450 and 8,456 square miles—an area about the size of New Jersey.

Most likely, this summer's Gulf dead zone will blanket about 7,980 square miles, roughly the same size as last year's zone, Scavia said. That would put the years 2009, 2008 and 2001 in a virtual tie for second place on the list of the largest Gulf dead zones.

It would also mean that the five largest Gulf dead zones on record have occurred since 2001. The biggest of these oxygen-starved, or hypoxic, regions developed in 2002 and measured 8,484 square miles.

"The growth of these dead zones is an ecological time bomb," said Scavia, a professor at the U-M School of Natural Resources and Environment and director of the U-M Graham Environmental Sustainability Institute.

"Without determined local, regional and national efforts to control them, we are putting major fisheries at risk," said Scavia, who also produces annual dead-zone forecasts for the Chesapeake Bay.

The Gulf dead zone forms each spring and summer off the Louisiana and Texas coast when oxygen levels drop too low to support most life in bottom and near-bottom waters.

The Gulf hypoxia research team is supported by the U.S. National Oceanic and Atmospheric Administration's Center for Sponsored Coastal Ocean Research and includes scientists from Louisiana State University and the Louisiana Universities Marine Consortium.

The forecast for a large 2009 Gulf hypoxic zone is based on above-normal flows in the Mississippi and Atchafalaya rivers this spring, which delivered large amounts of the nutrient nitrogen. In April and May, flows in the two rivers were 11 percent above average.

Additional flooding of the Mississippi since May could result in a dead zone that exceeds the upper limit of the forecast, the scientists said.

"The high water-volume flows, coupled with nearly triple the nitrogen concentrations in these rivers over the past 50 years from human activities, has led to a dramatic increase in the size of the dead zone," said Gene Turner, a lead forecast modeler at Louisiana State University.

Northeast of the Gulf, low water flows into the Chesapeake Bay shaped Scavia's 2009 forecast for that hypoxia zone.

The Bay's oxygen-starved zone is expected to shrink to between 0.7 and 1.8 cubic miles, with a "most likely" volume of 1.2 cubic miles—the lowest level since 2001 and third-lowest on record. The drop is largely due to a regional dry spell that lasted from January through April, Scavia said. Continued high flows in June, beyond the period used for the forecasts, suggest the actual size may be near the higher end of the forecast range.

"While it's encouraging to see that this year's Chesapeake Bay forecast calls for a significant drop in the extent of the dead zone, we must keep in mind that the anticipated reduction is due mainly to decreased precipitation and water runoff into the Bay," he said.

"The predicted 2009 dead-zone decline does not result from cutbacks in the use of nitrogen, which remains one of the key drivers of hypoxia in the Bay."

Farmland runoff containing fertilizers and livestock waste—some of it from as far away as the Corn Belt—is the main source of the nitrogen and phosphorus that cause the Gulf of Mexico dead zone.

Each year in late spring and summer, these nutrients make their way down the Mississippi River and into the Gulf, fueling explosive algae blooms there. When the algae die and sink, bottom-dwelling bacteria decompose the organic matter, consuming oxygen in the process. The result is an oxygen-starved region in bottom and near-bottom waters: the dead zone.

The same process occurs in the Chesapeake Bay, where nutrients in the Susquehanna River trigger the event. In both the Gulf and the Bay, fish, shrimp and crabs are forced to leave the hypoxic zone. Animals that cannot move perish.

The annual hypoxia forecasts helps coastal managers, policy makers, and the public better understand what causes dead zones. The models that generate the forecasts have been used to determine the nutrient-reduction targets required to reduce the size of the dead zone.

"As with weather forecasts, the Gulf forecast uses multiple models to predict the range of the expected size of the dead zone. The strong track record of these models reinforces our confidence in the link between excess nutrients from the Mississippi River and the dead zone," said Robert Magnien, director of NOAA's Center for Sponsored Coastal Ocean Research.

U.S. Geological Survey data on spring river flow and nutrient concentrations inform the computer models that produce the hypoxia forecasts.

The official size of the 2009 hypoxic zone will be announced following a NOAA-supported monitoring survey led by the Louisiana Universities Marine Consortium on July 18-26. In addition, NOAA's Southeast Area Monitoring and Assessment Program's (SEAMAP) is currently providing near real-time data on the hypoxic zone during a five-week summer fish survey in the northern Gulf of Mexico.

Source: http://www.sciencedaily.com/releases/2009/06/090618124956.htm