Manatees are hard of hearing

Manatees get run down by motorboats because they can't hear them coming, a new study suggests.

"It's a common belief that they must be too slow or too stupid to get out of the way," says Edmund Gerstein of the Florida Atlantic University in Boca Raton. Yet the animals can swim at several metres per second and are intelligent enough to remember hazards and avoid them.

That led Gerstein to investigate the animals' hearing. His team trained two captive-born males, Stormy and Dundee, to take a hearing test. The manatees were taught to wait underwater for a strobe light to flash. If a tone preceded the light, the animals were trained to press a striped paddle. If there was no tone, they pressed a white paddle.

The researchers found the threshold intensities below which the animals could no longer hear different frequencies. Their most acute hearing was at about 17 kilohertz, with a threshold intensity of 50 decibels. In contrast, at 05 kilohertz the threshold was about 50 decibels higher-meaning that a sound had to be 100 000 times as intense before the animals could hear it (The Journal of the Acoustical Society of America, vol 105, p 3575).

The frequency of a boat's motor is roughly 2 kilohertz, which is at the poor end of manatees' hearing range. Boats that slow down in an effort to avoid manatees produce even lower-frequency sounds, making it more difficult for the animals. Near the surface of the water, low tones also propagate poorly because of a phenomenon called Lloyd's mirror effect, where soundwaves bouncing off the water's surface interfere with one another.

"This work hopefully will help solve this problem," says Whitlow Au, a bioacoustics expert at the University of Hawaii in Manoa. Gerstein is already working on a high-frequency sonic beacon that could be attached to boat motors in order to warn manatees away.


Contact: Claire Bowles
New Scientist

Page: 1

Related biology news :

1. Manatees saved by ONR-supported technology
2. USGS Scientists Learn Lessons From Captive Released Manatees
3. Listen up! Mice may hold key to restoring human hearing loss
4. Evolution of whale hearing unfolds in fossil record
5. Drug prevents chemotherapy-induced hearing loss, study finds
6. When male fish hum, females swim in, thanks to hormones, adaptable hearing
7. Hormone helps fish to mate, may affect human hearing
8. U of T study finds music teachers at risk of hearing loss
9. Alcohol consumption can damage hearing
10. NAFTA arbitrators in environmental case agree to formal public input, a first for trade hearings
11. Gene mutations that cause hearing loss discovered

Post Your Comments:

(Date:5/16/2017)...   Bridge Patient Portal , an enterprise ... EMR Systems , an electronic medical record solutions ... established a partnership to build an interface between ... Centricity™ products, including Centricity Practice Solution (CPS), Centricity ... new integrations will allow healthcare delivery networks using ...
(Date:4/18/2017)... , April 18, 2017  Socionext Inc., a global expert ... a media edge server, the M820, which features the company,s hybrid ... software provided by Tera Probe, Inc., will be showcased during the ... the NAB show at the Las Vegas ... ...
(Date:4/11/2017)... Fla. , April 11, 2017 ... and secure authentication solutions, today announced that it ... Intelligence Advanced Research Projects Activity (IARPA) to develop ... Thor program. "Innovation has been a ... IARPA,s Thor program will allow us to innovate ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... BALTIMORE, Md. (PRWEB) , ... October 11, 2017 ... ... for digital pathology, announced today it will be hosting a Webinar titled, “Pathology ... of  Advanced Pathology Associates , on digital pathology adoption best practices and how ...
(Date:10/11/2017)... ... October 11, 2017 , ... A new study published in ... and fresh in vitro fertilization (IVF) transfer cycles. The multi-center matched ... , After comparing the results from the fresh and frozen transfer cohorts, the ...
(Date:10/10/2017)... , ... October 10, 2017 , ... ... Center’s FirstHand program has won a US2020 STEM Mentoring Award. Representatives of the ... for Excellence in Volunteer Experience from US2020. , US2020’s mission is to change ...
(Date:10/10/2017)... ... October 10, 2017 , ... USDM Life Sciences , ... life sciences and healthcare industries, announces a presentation by Subbu Viswanathan and Jennifer ... “Automating GxP Validation for Agile Cloud Platforms,” will present a revolutionary approach to ...
Breaking Biology Technology:
Cached News: