Environmental Monitoring
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December 2010 Issue
NOAA Awards Grant to Study Oxygen Depletion, Acidification
NOAA has announced it will award a five-year, $1.6 million grant to University of Delaware professor Timothy Targett and colleagues at the Smithsonian Environmental Research Center and Louisiana State University.
The award, through NOAA's Coastal Hypoxia Research Program, will support research to predict the impact of daily cycles of hypoxia and pH in shallow estuarine waters on ecologically and economically important finfish and shellfish.
Results of this study could help environmental and fisheries managers pinpoint key areas for habitat and fisheries restoration and better protect shallow-water estuarine habitat that serves a critical nursery function.
The deep waters of Chesapeake Bay, for example, experience hypoxia and even anoxia during summer. However, as continuous oxygen monitoring has increased in shallow tributaries and nearshore areas of estuaries worldwide, it has become apparent that many of these habitats experience day-night "swings" in oxygen concentrations that result in hypoxia and anoxia during night and early morning hours.
The study will examine how daily cycles of hypoxia impact growth, reproduction and survival of fish and shellfish in these productive shallow-water nursery areas. It will focus on species with significant commercial value for the region, including summer flounder, striped bass, weakfish, white perch and the eastern oyster, as well as important prey fish such as the mummichog.
The researchers also will study the effects of acidification, which is linked with hypoxia and may exacerbate hypoxia's impact on fish and oysters.
Scientists Observe Damage To Deep-Sea Corals in GOM
Government and academic scientists on a multiweek expedition this fall to explore deep-sea coral habitats in the Gulf of Mexico (GOM) have observed corals and associated communities of marine life that show evidence of recent damage. This year's cruise was the fourth of a multiyear collaboration sponsored by NOAA's Office of Ocean Exploration and Research and the Bureau of Ocean Energy Management, Regulation and Enforcement.
Operating from the NOAA Ship Ronald H. Brown and using a variety of tools, including the National Deep Submergence Facility's Jason II remotely operated vehicle (ROV), researchers were working at a site 1,400 meters deep and approximately seven miles southwest of the Macondo wellhead when they visually observed dead and dying corals with sloughing tissue and discoloration.
Dr. Charles Fisher, a professor of biology at Penn State University and chief scientist on the expedition, described much of the soft coral observed in one area as covered by what appeared to be a brown substance. Ninety percent of 40 large corals were heavily affected and showed dead and dying parts and discoloration. Another site 400 meters away had a colony of stony coral similarly affected and partially covered with a similar brown substance.
Sediment and coral samples were collected with the ROV and brought to the surface for analyses. Further testing will determine if the substance is oil, and if so, whether it is consistent with the release from the Deepwater Horizon oil spill, the researchers said.
"While this mission was not designed to be focused on oil spill research, the timing and location provided an opportunity to observe any impacts to our research areas," Fisher said.
Temperature, Pressure Sensors Hitch Ride on Arctic Whales
Scientists using sensors attached to narwhals, a type of Arctic whale known for its unicorn-horn-like tooth, have detected continued warming of the southern Baffin Bay off West Greenland. The temperatures of the waters have continued to rise since wintertime ocean temperatures were last effectively measured there in the early 2000s, the researchers reported October 23 in the Journal of Geophysical Research-Oceans.
During missions in 2006 and 2007, narwhals were tagged with sensors that recorded ocean depths and temperatures during feeding dives from the surface pack ice to the seafloor, as deep as 1,773 meters.
Scientists have had limited opportunities to measure ocean temperatures in Baffin Bay during winter months because of dense ice and harsh conditions. Cost is also a factor—it takes millions of dollars to mount a conventional expedition using an ice-breaking vessel and other specialized equipment and personnel. As a result, for the past decade, researchers used climatology data (long-term historical average observations) rather than direct ocean temperature measurements for winter temperatures in the area.
The study reports that the highest winter ocean temperature measurements in 2006 and 2007, from both narwhals and sensors deployed using helicopters, ranged between 4° and 4.6° C and that temperatures were on average nearly 1° C warmer than climatology data. Whale-collected temperatures also demonstrated that the thickness of the winter surface isothermal layer was 50 to 80 meters less than climatology data indicated.
NOAA funded the missions to tag and track narwhals as they made a fall migration from northwest Greenland to their wintering grounds in Baffin Bay. In total, 14 adult narwhals were tagged with sensors to record date and time, ocean temperature and depth. The data were automatically sent to a satellite when the narwhals surfaced for air between cracks in the sea ice. Each sensor tag provided up to seven months of data before falling off.
"[Narwhals'] natural behavior makes them ideal for obtaining ocean temperatures during repetitive deep vertical dives," said Kristin Laidre of the Polar Science Center in the University of Washington's Applied Physics Laboratory, lead scientist on the missions. "This mission was a proof-of-concept that narwhal-obtained data can be used to make large-scale hydrographic surveys in Baffin Bay and to extend the coverage of a historical database into the poorly sampled winter season."
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