Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How well do gray seals hear?

25.03.2014

TiHo researchers investigate the hearing of the marine mammals.

Researchers from the Institute for Terrestrial and Aquatic Wildlife Research of the University of Veterinary Medicine Hannover Foundation (TiHo) are investigating the hearing of gray seals (Halichoerus grypus) under the leadership of Professor Dr. Ursula Siebert and Dr. Andreas Ruser.


With specially adapted in-ear headphones TiHo researchers investigated the hearing of gray seals.

Photo: ITAW

They published the first results in the online specialist magazine Plos one (www.plosone.org). The investigations were financed by the German Federal Agency for Nature Conservation (BfN) in order to increase knowledge about the effects of underwater noise on marine mammals. They are part of a multi-year, extensive BfN research program. The measuring system was supported by Technical Center Army Office 71 of the German Armed Forces.

“We urgently need to learn more about how well and in which frequency range gray seals hear,” says Professor Dr. Ursula Siebert, Head of the institute. “The last scientific publication on this topic dates back to 1975.”

Noise pollution in the sea is continuously increasing: shipping traffic, construction works in the sea, blasting, sound cannons to search for crude oil or the use of sonar devices stress the animals. The scientists need precise data about the hearing of gray seals in order to assess the effects of underwater noise on the animals. This seal species, along with porpoises and seals, is among the most common marine mammals in the North and Baltic Seas.

For their current study, the researchers investigated six gray seals from rearing stations. Dr. Andreas Ruser explains: “Basically, we proceeded according to the principle which we know from ear specialists.”

In contrast to humans, however, animals cannot say when they hear a tone, so the challenge for the researchers was to find out whether the seals perceive a tone or not. The researchers sedated the gray seals shortly before they were to be released into the wild. Then they played tones to them and measured the nerve impulses transmitted from the cochlea to the auditory nerve. As soon as the animals woke up again, the researchers were able to release them into the wild.

Since seals close their external ear channel when sedated, it is impossible to treat them with ultrasound using speakers. “We therefore used specially adapted in-ear headphones,” explains Ruser. The researchers found out that gray seals, similar to humans, can hear in a frequency range between 1,000 and 20,000 hertz and are much more sensitive than previously known in a range higher than 3,000 hertz.

Furthermore, there are indications not yet confirmed that gray seals can also hear above 20,000 hertz. “Using this method, however, we can only prepare a so-called air audio diagram for wild animals, which means that measurements can only be carried out in the air. Sound waves are transmitted in a different manner under water. We therefore assume that gray seals hear even higher frequencies under water.”

Next, Ruser and his colleagues want to examine this difference with gray seals trained and held in human hands at the University of Southern Denmark, Odense: The gray seals must therefore “learn” to signalize whether they hear something, first above and then under water. The seals are thus to be trained to show a defined reaction as soon as they hear a tone. This training is carried out in the pool of the respective seal facility.

The tones are then played for the gray seals under controlled conditions using headphones or loudspeaker in the air and loudspeaker or hydrophones under water. “We are looking forward to the further results, particularly with regard to the hearing of the seals under water,” says Professor Siebert. “We are hoping for reliable evidence that shows to what extent seals are affected by the increasing noise pollution in the North and Baltic Seas.”

Background Information

Gray seals are the biggest wild predators in Germany. They can live up to 35 years. With a length of 230 centimeters and an average weight of 220 kilograms, males are considerably larger than females, which can be up to 180 centimeters in length and may weigh 150 kilograms.

The employees of the Institute for Terrestrial and Aquatic Wildlife Research work in Hannover and at a branch of the TiHo in Büsum in Schleswig-Holstein. The focal points of aquatic wildlife research are basic research, applied research and monitoring. The aim is to investigate the biology and ecology of marine mammals and to assess the influence of humans on animals, their health and their population.

Original Publication

In-air evoked potential audiometry of grey seals (Halichoerus grypus) from the North and Baltic Seas
Andreas Ruser, Michael Dähne, Janne Sundermeyer, Klaus Lucke, Dorian S. Houser, James J. Finneran, Jörg Driver, Iwona Pawliczka, Tanja Rosenberger, Ursula Siebert
Plos one, DOI: 10.1371/journal.pone.0090824

For technical questions, please contact

Dr. Andreas Ruser
University of Veterinary Medicine Hannover Foundation
Institute for Terrestrial and Aquatic Wildlife Research
Phone: +49 511 953-8156
andreas.ruser@tiho-hannover.de

Weitere Informationen:

http://www.tiho-hannover.de/aktuelles-presse/pressemitteilungen/pressemitteilung...

Sonja von Brethorst | idw - Informationsdienst Wissenschaft

Further reports about: BfN Medicine Veterinary Wildlife hear hertz humans mammals seals transmitted underwater

More articles from Life Sciences:

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

nachricht Snap, Digest, Respire
20.01.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Bodyguards in the gut have a chemical weapon

20.01.2017 | Life Sciences

SF State astronomer searches for signs of life on Wolf 1061 exoplanet

20.01.2017 | Physics and Astronomy

Treated carbon pulls radioactive elements from water

20.01.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>