First published study on hearing in wild cetaceans
The ocean is an increasingly industrialized space. Shipping, fishing, and recreational vessels, oil and gas exploration and other human activities all increase noise levels in the ocean and make it more difficult for marine mammals to hear and potentially diminish their range of hearing.
Two Bristol Bay beluga whales fluking. The research team captured and tested hearing in seven Bristol Bay beluga whales, one of six subpopulations of beluga whales in the U.S. (NMFS permit number 14610) (Photo courtesy of Alaska Dept. of Fish and Game)
“Hearing is the main way marine mammals find their way around the ocean,” said Aran Mooney, a biologist at Woods Hole Oceanographic Institution (WHOI). It’s important to know whether and to what extent human activity is negatively impacting them.
But how can we get marine mammals living in the wild to tell us what they’re able to hear?
“Same way we do it with human infants,” said Mooney. “You play a sound, then you measure the brain's response to the sound.”
Though Mooney makes it sound easy enough, he and his colleagues are the first to publish a study of hearing in wild marine mammals, with multiple marine mammals. The paper, “Baseline Hearing Abilities and Variability in Wild Beluga Whales (Delphinapterus leucas)” was published today in The Journal of Experimental Biology, on May 14.
In addition to Mooney, the research team included the paper’s lead author Manuel Castellote, from the Alaska Fisheries Science Center, which is part of the National Marine Fisheries Service, and the North Gulf Oceanic Society, and their colleagues from Alaska Department of Fish and Game, Alaska SeaLife Center, and the Georgia Aquarium.
The researchers worked over a two week period in southwest Alaska during the summer of 2012, capturing and testing seven Bristol Bay beluga whales, one of six subpopulations of beluga whales in the U.S. Enabling this study are recent advances in portable field testing equipment, rugged enough for field work. To conduct their hearing tests, the team temporarily maintained the individual animals as part of physical health exams. They used suction cups to attach a small speaker to its jaw—which in whales and dolphins conducts sound to both ears—and placed sensors on the animal’s head and back.
“The advantage is that it’s really fast,” said Mooney. “You can get one of these data points in about two or three minutes. A whole hearing range takes about half an hour.”
In human populations, there is variability in our hearing ability: older people don’t hear as well as younger people; males don’t hear high frequencies as well as females. But in the tested beluga population, there was surprisingly little variation.
“The bottom line is they all hear pretty well,” said Mooney. “Limitations to our study were that we had just seven animals who live in a pretty quiet environment without a lot of noise exposure. These might conserve their high-frequency better than humans, which makes sense; they need it for echolocation, and if they lose that, then they could lose of their abilities to find food and communicate.”
That this kind of study has never been reported before is an indication of the challenge of capturing and testing wild marine mammals.
“It's a bit of a project. It takes a lot of people and the right environment. But we've also shown that if you have the right setup it's easy to do,” said Mooney.
The team used three or four small inflatable boats and worked with Alaskan natives expert in spotting belugas, which have no dorsal fin and make only the smallest of ripples at the surface when they breathe. The guide the beluga into shallow water – shallow enough to stand in -- until they can gently capture the 8- 12-foot animals with a hoop and net.
“Then the animal won't try and swim away, once they feel contained, they're not going to fight,” said Mooney. “They will hang out there. Then you put a belly band stretcher underneath them which has little holes for the flippers. Then it goes over the belly, and that holds the animal during the test.”
The team caught and measure three females and four males and essentially gave them all physicals. In addition to the hearing test, they did ultrasounds on each of the animals and collected saliva or mucous from the blow hole to look for stress hormones and took a core of the blubber to look for PCBs and other organic compounds that may build up in the fats. Together, the data gives researchers a baseline of the animals’ health and a way to measure change in the population’s health over time and as environmental conditions change.
While hearing in the tested animals was good, the researchers note that human-caused ocean noise is believed to be a chronic stressor and has been identified as a threat to other populations of belugas. The increase in human activities in Arctic ecosystems as a result of sea ice loss is creating a special concern about increasing ocean noise in the Arctic and its potential impacts on whales and dolphins. They note that “expanding our knowledge of beluga hearing is key to an appropriate conservation management effort.”
Another driver for understanding their health and hearing now is a proposed mineral exploration and mining project in the area. The Pebble Mine project would exploit large deposits of copper, gold and molybdenum in the region. “It's not clear if it will directly affect the hearing of the belugas, but it will affect the ecology of what's up there, so the baseline health information is key,” said Mooney.
The results of this hearing study may also help validate studies of hearing in belugas in captivity .
The team hopes to return to the field this summer to test a larger number of animals and attach temporary data-logging tags to learn more about their foraging, diving, and social behaviors.
Funding for the project came from the Georgia Aquarium and the National Marine Mammal Laboratory of the Alaska Fisheries Science Center (NMML/AFSC). Field work also supported by National Marine Fisheries Service Alaska Regional Office (NMFS AKR), WHOI Arctic Research Initiative, WHOI Ocean Life Institute, U.S. Fish and Wildlife Service, Bristol Bay Native Association, Alaska Sea Life Center, Shedd Aquarium and Mystic Aquarium and the Office of Naval Research.
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment. For more information, please visit www.whoi.edu.
Originally published: May 14, 2014
WHOI Media Office | Eurek Alert!
How to detect water contamination in situ?
22.09.2016 | Tomsk Polytechnic University (TPU)
Quantifying the chemical effects of air pollutants on oxidative stress and human health
12.09.2016 | Max-Planck-Institut für Chemie
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.
In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...
Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.
K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...
23.09.2016 | Event News
20.09.2016 | Event News
16.09.2016 | Event News
26.09.2016 | Materials Sciences
26.09.2016 | Materials Sciences
26.09.2016 | Materials Sciences