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Ocean Research


April 2013 Issue

Hydrophones Facilitate Study of Human-Made Noise on Herring
Chelsea Technologies Group Ltd. (Surrey, England) has been working with the Norwegian University of Science and Technology (NTNU) for a number of years, starting with NTNU initially commissioning Chelsea to custom design a 6-meter vertical acoustic hydrophone array to conduct underwater acoustic experiments. This was followed by the design of three 8-meter-long, active hydrophone arrays. These arrays are now being used to map the sound field inside a fish pen at Austevoll, just south of Bergen, Norway.

The reactions of a school of herring (about 10,000 fish) to waterborne acoustic signals and noise of various types is currently being studied to get a better understanding of the environmental impact human-made noise can have on fish. The primary objective of the project is to gain an understanding of the interaction between direct stimuli and the information transfer between individuals in schooling fish, and to understand how this affects their behavior.

The marine acoustics team at NTNU is responsible for the acoustic modeling and instrumentation on the penned-herring project. It has conducted several experiments in the Trondheim fjord, leading to an optimized underwater acoustic transmittance and transfer of data. The use of the Chelsea acoustic arrays has simplified the testing process, NTNU said.

Vikings Could Have Used Sunstone as Navigational Tool
While examining a shipwreck, a team from France has discovered a transparent crystal, or sunstone, that the Vikings might have used as a navigational tool to locate the sun, the BBC reported. This discovery could be a clue to the mystery of how the Vikings were able to navigate on the high seas even before the magnetic compass was invented.

A team from the University of Rennes in France was examining a British shipwreck sunk in 1592 in the English Channel when they found an oblong crystal beside a pair of dividers, which led the team to think the crystal, which was the size of a cigarette packet, was a navigational tool.

The crystal is composed of Iceland spar, which is a calcite that diffracts light into two rays. The scientists tested a similar crystal and proved that by rotation, the point of convergence for the two beams could be determined, which would indicate the sun's direction.

The scientists said this method works on cloudy days and at sunset. They think the use of sunstones persisted for centuries possibly as a backup to the magnetic compass, which began being used in Europe in the 13th century.

New Life Forms Found at World's Deepest Hydrothermal Vents
A remote-controlled submarine exploring the world's deepest known hydrothermal vents has gathered numerous samples from the Caribbean Sea, Associated Press reported. The upcoming laboratory analysis is expected to reveal new life forms from the Cayman Trough at more than 5 kilometers depth.

'From body form alone, I am confident that we have found several new species on this expedition: probably a new species of sea anemone, a few species of bristle worms and some small crustaceans,' Jon Copley, chief scientist for the expedition of Britain's National Oceanography Centre, said on board the RRS James Cook.

About three years ago, Copley's team discovered the deepest known hydrothermal vent field, the Beebe at 4,960 meters depth, as well as new organisms in the Caribbean Trench. The trench's vents are among the world's hottest at around 400° C.

The study of the vents could shed light on the physics of supercritical fluids (acting like gases because they are so hot) and the chemical composition at those depths. Studies of the marine life there should show how animals disperse and evolve at those depths.

There are abundant populations of some species around the vents, particularly Rimicaris hybisae, an eyeless shrimp found by the research team in 2010. Blankets of shrimp often cover the rock beneath them, said one of the scientists.

Meadows of anemones were also found at the Beebe site.

Images of a 10-meter-tall mineral chimney were recorded, as well as a 30-meter-tall mound of minerals formed by the superheated fluid rushing from the vents.

Bright oranges and reds were seen on the seabed from iron, and blues and greens from copper.

Chemosynthetic bacteria form the base of the ultradeep ecosystem. They create food from the hydrogen sulphide and methane erupting from the vents, instead of using photosynthesis.

CLEANSEA to Determine Causes, Solutions for Marine Pollution
For the next three years, the CLEANSEA Project Consortium will assess the drivers and impact of marine litter in European seas and provide solutions. The research consortium was scheduled to hold its first meeting in Amsterdam, Netherlands, in February.

Advanced techniques in the fields of environmental toxicology, analytical chemistry, satellite imaging, oceanographic modeling and materials biodegradation testing will be used to assess the distribution, fate and impacts of marine litter. Policy options and management measures to mitigate marine litter will be recommended.

The research consortium consists of 17 partners from 11 European Union (EU) member states representing all EU marine coastlines: the Black, Mediterranean, North and Baltic seas, and the North Atlantic.

Marine litter is now on the European Commission's agenda. 'It's an increasingly serious threat to biodiversity, human and ecosystem health, our economy,' said EU Environment Commissioner Janez Potocnik.

The CLEANSEA project coincides with the main goal of the European Marine Strategy Framework Directive (2008/56/EC) of 'good environmental status' for all European marine areas by 2020. The EU's goal is to reduce marine litter to the level that does not damage the marine environment.

With a financial contribution from the EU's Seventh Framework Program, this €3 million project is coordinated by the Institute for Environmental Studies at the Vrije Universiteit in Amsterdam.


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