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August 2012 Issue

Ocean Eddies, Not Just Sun Trigger Atlantic Phytoplankton
Scientists have found evidence of eddies triggering the annual spring and summer North Atlantic phytoplankton bloom. These eddies swirl across the surface layer of the North Atlantic Ocean and sustain phytoplankton in the ocean’s shallower waters, where they can receive sunlight to fuel growth, thereby keeping them from being pushed downward by the vagaries of rough processes at the ocean surface.

“Our results show that, due to eddies, the bloom starts even before the sun begins to warm the ocean,” said Amala Mahadevan, an oceanographer at the Woods Hole Oceanographic Institution and lead author of the paper published in Science in July.

The eddies help explain the timing of the spring and summer bloom and its patchy appearance, which is shaped by the eddies.

The study focused on diatoms, phytoplankton that live in walls of silica. The scientists tracked a patch of seawater off Iceland and followed the progression of the bloom. In April 2008, they arrived in the North Atlantic aboard the Icelandic RV Bjarni Saemundsson. They launched four Seagliders, designed, built and operated by the University of Washington, in the rough seas and deployed a Lagrangian float, also from the university, that hovered below the water’s surface.

Lurking alongside the float were the 6-foot-long Seagliders, which dove to depths up to 1,000 meters. After each dive, the gliders, working in areas 20 to 50 kilometers around the float, rose to the surface and transmitted their stored data back to shore.

The float and gliders measured the temperature, salinity and velocity of the water, and gathered data on the chemistry and biology of the bloom, such as oxygen, nitrate and the optical signatures of the phytoplankton.

The ocean eddies were generated in a 3D model from a south-to-north variation of ocean temperature. The scientists hope to follow the bloom’s evolution across an entire year. This data could be integrated with a suite of physical-biological models to span the world’s oceans.


Toxic Pollutants Measured In Five Sea Turtle Species
Researchers at the Hollings Marine Laboratory (HML) and its partners measured in June concentrations of 13 perfluoroalkyl compounds (PFCs) in five endangered sea turtle species for the first time: the green, hawksbill, leatherback, loggerhead and Kemp’s ridley. Their PFC levels approach the amounts known to cause adverse health effects in other animals.

PFCs are man-made pollutants that infiltrate the food chain and affect neurobehavioral function and the immune system. The most common PFCs are perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA).

The turtles in this study had diets ranging up the food chain from sea grasses and algae to crabs. PFC concentrations were expected to be higher in species that fed farther up the food chain, since their prey’s tissues would probably concentrate the pollutants.

Plant-eating green turtles had the lowest plasma concentrations for the majority of PFCs examined, especially PFOS. Leatherbacks, loggerheads and Kemp’s ridleys had progressively higher PFOS concentrations. However, hawksbills—who browse low on the food chain, primarily on sponges—recorded the second-highest average concentration of PFOS and were the only species to have a detectable PFOA level. This may relate to the locations where they forage, or it may suggest that sponges have unusually high PFOS and PFOA concentrations.

The turtles’ plasma concentrations of PFOS were compared with previously reported concentrations shown to have adverse health effects in laboratory animals. The results showed that hawksbills, loggerheads and Kemp’s ridleys had PFOS concentrations approaching those linked to liver and neurobehavioral toxicity in other animals. Levels in loggerheads and Kemp’s ridleys approached those linked to thyroid disruption.

All five species had levels that approached those linked to suppressed immunity.


Vote Fails to Establish South Atlantic Whale Sanctuary
The South Atlantic Whale Sanctuary (SAWS) failed to meet the International Whaling Commission’s (IWC) required three-fourths majority vote to be established, Greenpeace announced in July. The SAWS would have protected Southern Hemisphere whales from commercial whaling.

Japan, China, Norway, Russia and Iceland opposed SAWS, as well as several smaller countries environmentalists say are allied with Japan, such as Nauru and Tuvalu, the Los Angeles Times reported.

Most Southern Hemisphere whales are migratory, feeding in the nutrient-rich waters of the Antarctic before travelling to tropical waters to give birth. They then migrate back to their feeding grounds in the south.

SAWS protection would help the recovery of the whale population, promote conservation and research, and help develop responsible whale watching, according to Greenpeace.

The whales also drive tourism for many coastal communities in South America.


Anemone Fish Able to Cope With Rising Ocean Acidity
Researchers at Australia’s ARC Centre of Excellence for Coral Reef Studies reported in July in Nature Climate Change that anemone coral reef fish may be better prepared to cope with rising CO2 in the world’s oceans because of their parents.

Global ocean acidity is expected to increase by 0.3 to 0.4 pH by the end of this century due to human activity.

The research showed that anemone fish can adjust to the changes expected in the oceans by 2100, provided their parents are also raised in more acidic water. When both parents and their offspring were exposed to more acidic water, they were able to compensate for the change. It is unknown whether this effect is lifelong or how parent fish pass on this ability to deal with acidity to their offspring.

Rising ocean acidity could lead to bone and shell development problems, and nervous system malfunction in sea life. Anemone fish are particularly hardy and may not be typical of all ocean fish, said the researchers, who want to extend their study.


2013:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
2012:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC

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