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Ocean Research


May 2013 Issue

Burger Boat Co. to Build New Grayling for USGS
The U.S. Geological Survey (USGS) awarded in April a contract for the construction of a large research vessel for Lakes Huron, Michigan and Superior to Burger Boat Co. of Manitowoc, Wisconsin.'

The vessel will replace the'38-year-old'Grayling,'bringing the USGS Great Lakes Science Center (GLSC) large vessel fleet up-to-date.

The new'Grayling'will be stationed at the USGS base in Cheboygan, Michigan, and will come fully equipped with 21st-century laboratories and scientific instrumentation to support fishery science for the Great Lakes.'

The funding for this expenditure was accrued from two prior appropriations and held in an account unaffected by federal sequestration.'

The replacement ship is expected to be a commercial grade 78-foot vessel, and will be designed and constructed for a 40-to-50-year service life. This vessel will be capable of performing critical scientific and mission-related tasks, including dragging nets along the lake bottom, catching fish, and using sound-waves to detect fish and assess their abundance.

JMS Naval Architects & Salvage Engineers of Mystic, Connecticut, developed the preliminary design of the new'Grayling.

The USGS GLSC maintains a fleet of fishery research vessels on each of the Great Lakes to meet the scientific research needs of state, tribal and federal resource managers for understanding and effectively managing the Great Lakes fishery.

First Digital Map of Antarctic Seafloor Created
An international team of scientists led by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research has for the first time created a digital map of the entire Antarctic seafloor. The International Bathymetric Chart of the Southern Ocean (IBCSO) shows the detailed topography of the seafloor for the entire area below 60o South. The IBCSO data grid and the corresponding Antarctic chart are available at www.ibcso.org and are intended to improve understanding and prediction of sea currents, geological processes or the behavior of marine life.

Scientists from 15 countries and more than 30 research institutions brought together their bathymetric data from nautical expeditions. The data set comprised some 4.2 billion individual values, and the scientists interpolated the data set, too. As a result, the IBCSO data grid has a resolution of 500-times- 500-meters. This means that one data point reflects the depth of a sea area of 500-times-500-meters.

Where older models only offer a glimpse of a mountain in the deep sea, IBCSO shows an elevation with sharp ridge crests and deep channels in the slopes. A formerly flat point at the bottom of the Riiser-Larsen Sea can now be identified as a 300-meter-deep offshoot of the underwater Ritscher Canyon which runs more than 100 kilometers from the southwest to the north.

More than 80 percent of the area of the South Polar Sea is still unchartered.

New Sea Level Rise Models Predict Early Pacific Inundation
Dynamic modeling of sea level rise, which takes storm wind and wave action into account, indicates future problems for some low-lying Pacific islands under climate-change scenarios, compared to the passive computer modeling used in earlier research, according to a new U.S. Geological Survey (USGS) report.

The report compared passive 'bathtub' inundation models with dynamic models for two of the Northwestern Hawaiian Islands in the Papahanaumokuakea Marine National Monument. Midway Atoll, with islands on the shallow (2 to 8 meters deep) atoll rim and a deep, central lagoon, and Laysan, which is higher, with a 20 to 30 meter deep rim and an island in the center of the atoll, were studied.

The two locations exhibit landforms and coastal features common to many Pacific islands. Managed by the U.S. Fish and Wildlife Service, they are also among the world's most important nesting and breeding sites for migratory birds and other wildlife.

Passive 'bathtub' inundation models typically used to forecast sea-level rise impacts suggest that most of the low-lying atolls in the Pacific Islands will still be above sea level for the next 50 to 150 years. But when taking wave-driven processes into account, the new forecast predicts that many of the atolls will be inundated, contaminating freshwater supplies and thus making the islands uninhabitable much sooner than had been expected. At least twice as much land is forecast to be inundated on Midway and Laysan by sea level rise than was projected by passive models.

These findings have importance not only for island wildlife, but for the tens of thousands of people who live on other low-lying Pacific Island groups such as those in the Republic of the Marshall Islands and the Federated States of Micronesia. The new models offer tools for forecasting where agricultural land may be damaged by repeated saltwater overwash, as well as where groundwater may be contaminated by saltwater.

Copepods Swim With Power Strokes to Escape Predators
To escape from the jaws and claws of predators in cold, viscous water, marine copepods switch from a wave-like swimming stroke to big power strokes, a behavior that has been revealed via 3D high-speed digital holography, according to a study in the Proceedings of the National Academy of Sciences. The technique uses a microscope with a laser and a high-speed digital camera to catch the rapid movements of the microscopic animals in a 3D volume of liquid.

Copepods are key components of marine food webs. Understanding how they might respond to changes in the environment is important for assessing the health of oceans now and in the future.

Water viscosity naturally increases as the temperature drops. The researchers discovered that the power stroke is triggered only by colder temperature, not viscosity alone because the muscles that control the copepods' appendages are affected by temperature.

If viscosity increases without temperature change'—e.g., during an algal bloom or pollution event—the copepods' escape ability declines. This affects their populations as coastal algal blooms and pollution increase.


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