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April 2011 Issue

Majority of Coral Reefs Under Threat, Analysis Finds
A new comprehensive analysis finds that 75 percent of the world's coral reefs are currently threatened by local and global pressures. The report, Reefs at Risk Revisited, was released by the World Resources Institute (WRI) and a network of other organizations.

The report shows that local pressures—overfishing, coastal development and pollution, for example—pose the most immediate and direct risks, threatening more than 60 percent of coral reefs today. In addition to these problems, global pressures such as rising sea temperatures and ocean acidification from carbon dioxide pollution are leading to coral bleaching.

According to the new analysis, if left unchecked, more than 90 percent of reefs will be threatened by 2030 and nearly all reefs will be at risk by 2050. The report includes multiple recommendations to better protect and manage reefs, such as marine protected areas. The report is an update of "Reefs at Risk," released by WRI in 1998. For more information, visit www.wri.org.

Report Links Naval Sonar To Whale Strandings
The knowledge most critical to protecting whales from sonar involves measuring the threshold between safe and risky exposure levels, but it was unknown until recently how beaked whales respond to sonar, much less the levels that pose a problem.

A team of researchers led by Peter Tyack, a senior scientist at Woods Hole Oceanographic Institution, have reported the first data on how beaked whales respond to naval sonar exercises. Their results, published in March in PLoS ONE, suggest that sonar indeed affects the behavior and movement of whales.

Tyack and his colleagues developed experiments to slowly increase the level of sonar on a tagged whale, to stop exposure as soon as the whale started responding, to measure that exposure and to define the response. The experimental approach used tags to measure acoustic exposure and behavioral reactions of beaked whales to one controlled exposure each of simulated military sonar, killer whale calls and band-limited noise.

The research was conducted on a naval testing range where an array of hydrophones covered the seafloor, allowing whale sounds to be monitored over 600 square miles.

"During actual sonar exercises, beaked whales were primarily detected near the periphery of the range, on average 16 kilometers away from the sonar transmissions," they report. "Once the exercise stopped, beaked whales gradually filled in the center of the range over two to three days."

The scientists say the results indicate that naval sonar disrupts whale foraging and other behavior at exposures well below those assumed by regulators. Behavior tended to be disrupted at around 140 decibels, a much lower level than current regulations that anticipate disruption of behavior at around 160 decibels. For more information, visit www.whoi.edu.

Working Group Plans Biodiversity Observing Network
The National Oceanographic Partnership Program (NOPP) released a report in March to plan for the implementation of a marine Biodiversity Observing Network (BON).

There is no standardized, coordinated approach to monitoring marine biodiversity. Scientists and representatives of seven federal agency sponsors met last May to discuss the components of BON. The resulting report, "Attaining an Opera?tional Mar?ine Biodiversity Observation Network Synthesis," provides a set of recommendations and case studies for implementing a national and global marine BON.

Steering committee members came up with recommendations that include: coordinate biodiversity sampling across taxa, habitats, hierarchical levels and methods from microbes to mammals; maximize compatibility of BON with legacy data; establish one or more biodiversity observation centers to coordinate sample processing; synthesize and make accessible marine taxonomic resources; invest in developing new approaches for automated sample processing; modernize and enhance the nation's physical infrastructure for marine exploration; and initiate an integrated marine BON demonstration project soon. For more information, visit www.nopp.org.

Scientists Seek to Save Threatened Nassau Grouper
Scientists studying the Nassau grouper, a Caribbean reef fish decimated by overfishing, say it is showing tentative signs of recovery off the Cayman Islands since the government there imposed protective restrictions eight years ago. However, their research also shows the groupers' behavior during spawning—and subsequent dispersal of their larvae—may threaten the long-term viability of the species without further protection.

"Nassau groupers form large aggregations to spawn," said Scott Heppell, a fisheries ecologist at Oregon State University. "The same trait that promotes their reproductive success, however, also makes them extremely vulnerable to fishing."

Heppell and his colleagues are working with the Reef Environmental Education Foundation and the Cayman Islands Department of Environment on a project to learn more about the fish.

The researchers deployed short- and long-term drifter buoys to see where currents potentially carry the larvae. They also tagged several adult fish and set up telemetry sites to track the adults en route to their spawning aggregation.

What they found is that the groupers aggregate during the first full moon after the winter solstice. As many as 4,000 fish will gather at a site west of Little Cayman Island, then spawn some three to eight days later. The long-term buoys eventually drifted south, suggesting that some larvae would be carried far from the islands. However, halfway through their 45-day journey, the buoys rode currents back to within 100 kilometers of the Cayman Islands.

"The combination of spawning when eddies arrive, and the circular nature of long-term currents has the effect of keeping fish close to home," Heppell said. "Despite protections, the other sites haven't yet regenerated—and the limited distribution of larvae may be the reason."

For more information, visit www.reef.org/.


2012:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
2011:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC

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