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New acoustic sensors are being used in research and conservation projects around the world, with some very important practical results. Among them is improved monitoring of endangered North Atlantic right whales in an effort to reduce ship strikes, a leading cause of their deaths.

Sofie Van Parijs is one of many researcher whose work is decribed this month in the journal Marine Ecology Progress Series. Her paper is one of about a dozen in a special theme issue focused on acoustics in marine ecology. Van Parijs, who currently heads the NEFSC's Protected Species Branch, is also a co-author of a related paper on acoustic interference or masking, in which marine animals alter their use of sound as a result of changing background noise.

Van Parijs and her colleagues focus on two types of acoustic sensors, real-time and archival. Real-time sensors are mounted on surface buoys, usually anchored or cabled to the ocean bottom, or deployed as arrays towed from a surface vessel. Archival sensors are affixed on bottom-moored buoys equipped with hydrophones to continuously record ocean sounds for long periods of time, often up to three months, before the sensors are temporarily recovered and their batteries refreshed. Some archiving sensors can be mounted of individual animals.

“Marine animals live their lives and communicate acoustically across different time and space scales and use sound for different reasons,” said Van Parijs. “We need to use the right tool in the right place for the right need. There is no ‘one size fits all’ when it comes to using technology in the ocean.”

Large whales move and communicate over great distances, while smaller whales and dolphins tend to communicate over smaller areas. Pinnipeds, the group of marine mammals that includes seals, walrus and sea lions, can breed on land, on ice or in the water, and move and communicate from small to medium distances. Human-produced sounds complicate the sensing problem by adding sounds to what can be a very noisy environment.

The use of passive acoustic monitoring is increasing as improved reliability and lower hardware and software costs provide researchers with a set of tools that can answer a broad range of scientific questions. This information can, in turn, be used in conservation management and mitigation efforts. While most of the new technologies have been applied in studies of whales and dolphins, the researchers say the sensors can also be used in studying pinnipeds, sirenians (manatees and dugongs) and fish.

Further Reading: Northeast Fisheries Science Center

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Labels: environment, technology, whale and dolphins

Swarms of miniature robotic ocean explorers that could one day help predict where ocean currents will carry oil spills, and which marine areas should be protected.

These autonomous underwater drifters will trace the fine details that can determine underwater ocean currents of a few kilometers. These are important for understanding marine protected areas, algal blooms, oil spills and the path sewage takes after it is pumped into the ocean.

"Maybe there has been an oil spill in the ocean and we want to establish very quickly how and where the spill might move. We are developing the algorithms that will keep a swarm of autonomous underwater explorers (AUEs) coordinated so they can follow the flow of the ocean currents and give us data on the spill as it is moving around," explained Jorge Cortes, a professor in the Mechanical and Aerospace Engineering Department at the UC San Diego Jacobs School of Engineering.

In addition to predicting where oil will travel, scientists can use this information on the flow of ocean currents in order to improve their models—and ultimately their understanding—of how ocean currents operate on the scale of kilometers and what this means for ocean life and for determining where marine protected areas should be established.

According to Jules Jaffe and Peter Franks, the two Scripps Institution of Oceanography researchers, the robot swarms could aid in science’s development of marine protected areas by following currents for determining critical nursery habitats and for tracking harmful blooms of algae.

The project differs from related work on networks of underwater robots in that the robot swarms the UCSD researchers are developing are significantly smaller and less expensive. At the same time, these robot swarms will be far more capable of making use of the information they collect on the fly in order to improve the accuracy of their task at hand.

Small armies of such robots will concurrently map currents and sense the environment. The robots relay their sensed data when they surface.

The robots will work through a system under which several football sized devices are deployed in conjunction with many—tens or even hundreds—of pint-sized underwater explorers. As they move about the ocean, the smaller-sized robots will use acoustic transmissions from the "motherships" to ascertain their positions. Collectively, the entire swarms of robots will help track fine ocean currents and flows that organisms at the small scale, tiny abalone larvae, for example, experience in the ocean.

"AUEs (Autoonomous Underwater Explorers) will give us information and statistics to figure out how the small organisms survive, how they move in the ocean and the physical dynamics they experience as they get around," said Franks. "AUEs should improve our ocean models and eventually allow us to do a better job of following the weather and climate of the ocean, as well as help us understand things like carbon fluxes."

Franks, who conducts research on marine phytoplankton, among other areas, says the new concentration on dense sampling at small scales will help resolve some of the patchiness in understanding the physical and biological properties on those scales.

"Plankton are somewhat like the balloons of the ocean floating around out there," he said. "We are trying to figure out how the ocean works at the scales that matter to the plankton. You put 100 of these AUEs in the ocean and let 'er rip. We'll be able to look at how they spread apart and how they move to get a sense of the physics driving the flow."

Further Reading:
UC San Diego Jacobs School of Engineering
National Science Foundation
Ocean Research Robots: A Future Vision for Ocean Observation

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Labels: environment, research, SCUBA News, technology

The National Science Foundation has announced agreement for vast undersea observing network. Called the Ocean Observatories Initiative (OOI) it will provide a network of undersea sensors for observing complex ocean processes such as climate variability, ocean circulation and ocean acidification at several coastal, open-ocean and seafloor locations.

Continuous data flow from hundreds of OOI sensors will be integrated by a sophisticated computing network, and will be openly available to scientists, policy makers, students and the public.

Advanced ocean research and sensor tools are a significant improvement over past techniques. Remotely operated and autonomous vehicles go deeper and perform longer than submarines. Underwater samplers do in minutes what once took hours in a lab. Telecommunications cables link experiments directly to office computers on land. At sea, satellite uplinks shuttle buoy data at increasing speeds.

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Labels: environment, SCUBA News, technology

Scientists are celebrating the first successful deployment and retrieval in Australia of a remotely controlled, deep ocean-going robotic submarine destined to play a central role in measuring changes in two of Australia’s most influential ocean currents.

Under the joint CSIRO Wealth from Oceans National Research Flagship and Integrated Marine Observation System (IMOS) project, the underwater ocean glider was launched in February on a two-month, 1,500 kilometre voyage.

With its porpoising motion and an ability to descend to a depth of nearly 1,000 metres, the $A200,000 robotic glider is being trialled in the Tasman Sea and the Indian Ocean as the latest tool in Australia’s $A94 million marine observing network.

The glider’s sensors measure temperature and salinity, as well a range of biological parameters including oxygen and turbidity.

Senior CSIRO Wealth from Oceans Flagship researcher Ken Ridgway, says the Tasman Sea trial has generated new confidence among scientists broadening the array of instruments available to them to better understand the East Australian Current and Leeuwin Currents.

“Ocean currents around Australia are critical to so many aspects of nature and human activity,” Mr Ridgway says. “With the East Australian and Leeuwin Currents, we need to understand how they change from season to season and year to year, and the extent of their influence on local coastal conditions, as this affects climate, weather, fisheries, shipping and more.

Together with data from research vessels, satellites and moored, drifting and expendable instruments, the glider will add a new dimension to profiling the oceans around Australia. But there are still challenges to be overcome.

“In a lot of ways this first deployment is as much learning how to pilot the glider and guide it through and around the eddies of the East Australian Current as it is getting about the data we want,” Mr Ridgway says.

A recent innovation in oceanography, the winged gliders are programmable and guided by Global Positioning Systems. They glide during depth changes, driven by an inflated oil filled chamber. However, because the ocean currents can be faster than the glider’s speed, ensuring they are not swept away has been a difficult process.

“The appeal of these instruments is that they are out working while the scientist can be assessing what is near-real time information about ocean conditions,” Mr Ridgway says.

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Robotic sea glider flies through water

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Labels: Australia, research, SCUBA News, technology