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http://www.foxnews.com/scitech/2012/04/08/whales-sensed-deepwater-horizon-oil-rig-disaster/

By Peter Gwynne
Published April 08, 2012
Inside Science News Service

A technique that monitors whales through the sounds they emit has answered a key issue raised by the explosion of the Deepwater Horizon oil rig in the Gulf of Mexico two years ago this month.

The sound-monitoring technique revealed that sperm whales retreated from the immediate area around the spill caused by the explosion.

“There’s obvious evidence of relocation,” said team member Azmy Ackleh, professor and head of mathematics at the University of Louisiana at Lafayette.

The discovery is important because it provides information about a species almost hunted to extinction for its valuable oil in the 19th century.

Sperm whales are listed as endangered under the terms of the United States Endangered Species Act, and estimates of their population vary between 200,000 and 1.5 million worldwide.

However, said Vassili Papastavrou, lead whale biologist for the International Fund for Animal Welfare who did not work on the study, “sperm whales are difficult animals to count, because they spend so much of their lives beneath the surface. The overall population estimates are so uncertain that it is not possible to determine trends.”

The discovery of their relocation also indicates the value of “passive” acoustic technology, which quietly listens for things instead of actively bouncing sounds off objects to find them.

This approach, first tried in the 1980s, uses hydrophones mounted on buoys to detect “clicks,” the powerful sounds emitted by the sperm whales. The University of Louisiana team, led by Natalia Sidorovskaia, associate professor and chair of the physics department, has extended the technology to localize and track sperm whales and to estimate their populations, and to do the same for other marine mammals, including other types of whales and dolphins.

Traditionally, zoologists have measured the location and size of whale populations by spotting them from boats or tagging individual whales with radio transmitters. While visual surveys are often inaccurate, tagging is very expensive.

The use of sound overcomes both problems.

“The usefulness of passive acoustics is generally under-appreciated, and the effort to develop it as a long-term monitor tool is timely,” said Donald Baltz, professor and chair of the department of oceanography and coastal sciences at Louisiana State University, who was not involved with the study.

“As long as we can hear the whales, we can count them,” Sidorovskaia said. “Passive acoustic measurements are not dependent on weather or light conditions and are much cheaper.”

Sperm whales transmit three types of sound, Sidorovskaia said. An echolocation signal is used in the way humans use radar, which helps the whales locate the ocean bottom and identify prey. A second signal serves as communication between whales. And the third is a short-range echolocation signal emitted when they are very close to their prey. Sidorovskaia said it’s probably “for more accurate short-range prey tracking.”

The range of frequencies in the sound signals, otherwise known as bandwidth, differentiates sperm whales from other whales, in much the same way that different cell-phone providers use different parts of the radio-frequency spectrum for managing communications.

“Each animal has a particular bandwidth,” Ackleh explained. “It’s a low bandwidth for sperm whales.”

By using enough hydrophones, the team can determine more than the density of sperm whales in any part of the sea.

“We can determine the range and depth of the whales,” Sidorovskaia said. “We can even track whales’ diving patterns based on the signals they produce.”

The team used passive acoustics to monitor a “resident population” of female sperm whales and their calves off the Louisiana coast in 2001, 2002 and 2007.

After the Deepwater Horizon explosion and spill, team members realized that the hydrophones they used for those recordings had been placed nine, 25, and 50 miles from the ill-fated oil rig.

So they set up fresh hydrophones in the same locations, collected acoustic signals characteristic of sperm whales, and applied statistical methods to compare the species’ population before and after the spill.

“A comparison of the 2007 and the 2010 recordings shows a decrease in acoustic activity and abundance of sperm whales at the nine-mile site by a factor of two, whereas acoustic activity and abundance at the 25-mile site has clearly increased,” the team wrote in the Journal of the Acoustical Society of America.

Just why the sperm whales moved away from the site is unclear. One possibility is that they followed their food sources out of the spill area. Sperm whales feed on giant squid, for which they dive about half a mile below the sea surface. They are also known to follow fishing boats and snag fish off their lines.

The team has garnered other firsts in applying passive acoustics. For example, it is building a library of whales’ “voiceprints” based on the sounds they make, which they can then use to locate and track single whales.

“This is very new,” Sidorovskaia asserted. “Our group would claim the initial idea.”Other research involves listening for beaked whales and refining the technology for more precise location of marine mammals. “We’re looking at a two-dimensional circle in the water now,” Ackleh said. “We hope eventually to detect animals in three-dimensional spheres.”

Read more: http://www.foxnews.com/scitech/2012/04/08/whales-sensed-deepwater-horizon-oil-rig-disaster/#ixzz1rmnFNdmg

Special thanks to Richard Charter

http://www.scientificamerican.com/article.cfm?id=phytoplankton-population

News | Energy & Sustainability

Researchers find trouble among phytoplankton, the base of the food chain, which has implications for the marine food web and the world’s carbon cycle

By Lauren Morello and ClimateWire | July 29, 2010 | 49

The microscopic plants that form the foundation of the ocean’s food web are declining, reports a study published July 29 in Nature.

The tiny organisms, known as phytoplankton, also gobble up carbon dioxide to produce half the world’s oxygen output—equaling that of trees and plants on land.

But their numbers have dwindled since the dawn of the 20th century, with unknown consequences for ocean ecosystems and the planet’s carbon cycle.

Researchers at Canada’s Dalhousie University say the global population of phytoplankton has fallen about 40 percent since 1950. That translates to an annual drop of about 1 percent of the average plankton population between 1899 and 2008.

The scientists believe that rising sea surface temperatures are to blame.

“It’s very disturbing to think about the potential implications of a century-long decline of the base of the food chain,” said lead author Daniel Boyce, a marine ecologist.

They include disruption to the marine food web and effects on the world’s carbon cycle. In addition to consuming CO2, phytoplankton can influence how much heat is absorbed by the world’s oceans, and some species emit sulfate molecules that promote cloud formation.

A continuing mystery story
“In some respect, these findings are the beginning of the story, not the end,” Boyce said. “The first question is what will happen in the future. We looked at these trends over the past century but don’t know what will happen 10 years down the road.”

The study “makes a sorely needed contribution to our knowledge of historical changes in the ocean biosphere,” said David Siegel of the University of California, Santa Barbara, and Bryan Franz of NASA in an essay, also published in Nature.

“Their identification of a connection between long-term global declines in phytoplankton biomass and increasing ocean temperatures does not portend well for [ocean] ecosystems in a world that is likely to be warmer,” they wrote. “Phytoplankton productivity is the base of the food web, and all life in the sea depends on it.”

Boyce said he and his co-authors began their study in an attempt to get a clearer picture of how phytoplankton were faring, given that earlier studies that relied on satellite measurements produced conflicting results.

Biggest declines at the poles
The scientists dug back into the historical record, well past 1997, the year continuous satellite measurements began. They examined a half-million data points collected using a tool called a Secchi disk, as well as measurements of chlorophyll—a pigment produced by the plankton.

The Secchi disk was developed in the 19th century by a Jesuit astronomer, Father Pietro Angelo Secchi, when the Papal navy asked him to map the transparency of the Mediterranean Sea.

What Secchi produced was a dinner plate-sized white disk that is lowered into ocean water until it cannot be seen anymore. The depth it reaches before disappearing gives a measure of water clarity.

That can be used as a proxy for phytoplankton population in a given area, since the tiny organisms live close to the ocean’s surface, where they are exposed to sunlight they use to produce energy.

Data gathered with a Secchi disk are roughly as accurate as observations collected by satellites, Boyce said, although satellites have greater global reach.

The researchers found the most notable phytoplankton declines in waters near the poles and in the tropics, as well as the open ocean.

They believe that rising sea temperatures are driving the decline. As surface water warms, it tends to form a distinct layer that does not mix well with cooler, nutrient-rich water below, depriving phytoplankton of some of the materials they need to turn CO2 and sunlight into energy.

Special thanks to Marine Life Health Reports

http://www.sciencedaily.com/releases/2012/03/120328090941.htm

ScienceDaily (Mar. 28, 2012) — As corals continue to decline in abundance around the world, researchers are turning their attention to a possible cause that’s almost totally unexplored — viral disease.

It appears the corals that form such important parts of marine ecosystems harbor many different viruses — particularly herpes. And although they don’t get runny noses or stomach upset, corals also are home to the adenoviruses and other viral families that can cause human colds and gastrointestinal disease.

In a research review published in the Journal of Experimental Marine Biology and Ecology, scientists point out that coral declines are reaching crisis proportions but little has been done so far to explore viral disease as one of the mechanisms for this problem.

“Coral abundance in the Caribbean Sea has gone down about 80 percent in the past 30-40 years, and about one-third of the corals around the world are threatened with extinction,” said Rebecca Vega-Thurber, an assistant professor of microbiology at Oregon State University.

“We’ve identified 22 kinds of emerging disease that affect corals, but still don’t know the pathogens that cause most of them,” Vega-Thurber said. “Most researchers have looked only at bacteria. But we suspect viruses may play a role in this as well, and it’s important to learn more about what is causing this problem. Corals are the building blocks of the tropical seas.”

A research program at OSU, one of only two of its type in the world, is studying viral “metagenomics” in corals, meaning the analysis of multiple genomes at the same time. It may help explain one of the underlying causes of coral decline, Vega-Thurber said, and is one of the most comprehensive analyses yet done on the types of viruses in a marine animal. It may also shed light on the broader range of viruses that affect not only corals but many other animals, including humans.

One of the surprises from recent research was the predominance in corals of herpes viruses — similar but not identical to the herpes virus that can infect humans. Herpes viruses appear to constitute a majority of the viruses found in corals, and one experiment showed that herpes-like viral sequences were produced in coral tissues after acute episodes of stress.

“We were shocked to find that so many coral viruses were in the herpes family,” Vega-Thurber said. “But corals are one of the oldest animal life forms, evolving around 500 million years ago, and herpes is a very old family of viruses that can infect almost every kind of animal. Herpes and corals may have evolved together.”

It’s not yet certain, researchers say, whether the viruses being found on corals are actually causing diseases.

“Just because you harbor a virus doesn’t mean you are getting sick from it,” Vega-Thurber said. “This is part of what we have to pin down with further research.”

Some of the possible causes of coral decline that have been identified so far include global warming that causes coral bleaching, loss of symbiotic algae that help nourish corals, pollution such as sewage runoff, and human-coral interactions.

A “mucus” sometimes found on corals can harbor human-borne viruses, and levels of these viruses have been correlated with terrestrial human population density.

“We have found that nutrient increases from pollution can cause increased levels of viral infection, as do warmer water and physical handling,” Vega-Thurber said. “Now we have to determine if those increases in infection cause actual diseases that are killing the coral.”

Corals are often a major component of marine ecosystems and biodiversity, especially in the tropics. They host thousands of species of fish and other animals. And whether or not viruses are implicated in coral disease, it may also be that they are passing diseases along to fish.

Research is “likely to reveal that viruses have numerous and profound roles on coral reefs,” the scientists wrote in their study. “As the diversity, distribution and function of reef-associated viruses becomes increasingly well defined, so will our ability to predict, prevent and/or mitigate disease epizootics on coral reefs.”

Special thanks to Robert Bolland PhD via Coral-list

Judith Lang via coral.aoml.noaa.gov

10:33 AM (7 hours ago) March 14th, 2012

Dear All,
New aids for identifying the species of corals and fishes in the wider Caribbean that can occur in AGRRA surveys are now available for downloading at:
www.agrra.org/method/trainingid.html

Many new photographs and, for the corals, a few taxonomic revisions are included in these materials.

Additional AGRRA datafiles will be posted online in the near future.

Kind regards,
Judy

Special thanks to:
Coral-List mailing list
Coral-List@coral.aoml.noaa.gov
http://coral.aoml.noaa.gov/mailman/listinfo/coral-list