Dear bioacoustics list,
I'd like to forward following compilation of answers to the question:
Are there any indications giving reasons for assuming that smaller marine
mammals
could be sensitive to infrasonic noise?
from Klaus-Richard Sperling <[EMAIL PROTECTED]>, sent to the list a few weeks
ago.
Thanks a lot for your responses!
Ursula Verfuss
_______________________________
Thank you to all of the responders of my inquiry. Herewith, I wish to send out
some
kind of resume and some comments. Hoping for Your interest I remain
Y. S. Klaus-Richard Sperling
RESPONSE: The following colleagues had responded:
* Klaus Lucke ([EMAIL PROTECTED]) has sent a large collection of literature
on
related issues. Some of the papers indicate that porpoises are sensitive to
low
frequency (however, not necessarily infrasound) noise.
* Lindy Weilgart ([EMAIL PROTECTED]) wrote me, that to her knowledge no
evidence
exists in the literature which could give proof for the sensitivity of harbour
porpoises to infrasound. Large whales are, indeed, sensitive, but it is
unclear
whether or not that is true for the smaller ones. She puts, however some
emphasis to
the fact that "hearing" and perception is not the same thing. She gave me the
paper of
S. Koschinski et. al. "Behavioural reactions of free-ranging porpoises and
seals to
the noise of a simulated 2 MW windpower generator" in: Marine Ecology Progress
Series
vol. 265; 263-273 [2003], There the behaviour of free living porpoises to the
noise of
a windmill played from a CD-recorder is described. They say: "... harbour
porpoises
and harbour seals are able to detect the low frequency sound generated by
offshore
wind turbines." and: "... certain sounds will be perceivable to harbour seals
and
harbour porpoises at 10s or even 100s of kilometres from the constructio!
n site ...".
* Michael L. Fine ([EMAIL PROTECTED]) sent his paper on acoustic communication
in
freshwater gobies and pointed at the arguments therein. In his understanding
they are
also applicable for shallow marine waters. He expects that infrasound will not
be a
problem.
* Christine Erbe ([EMAIL PROTECTED]) pointed out that infrasonic noise may not
be
audible but, nonetheless, perceivable. She expressed doubts that windmills
would
produce such energetic infrasound that acute injuries must be expected.
* Magnus Wahlberg ([EMAIL PROTECTED]) has sent one of his papers
(Wahlberg/Westerberg:
"Fish may hear and react to sounds from offshore windmills" in prep.). It
describes
investigations on three windparks in Sweden. He reviews measurements of
windmill noise
in Sweden and concludes that there is no evidence for the levels being high
enough to
cause physiological damages in fish, but for reactions even over long
distances. He
says that his conclusions should be interpreted with great care as the
existing data
is prone to significant incertainties.
* Friedrich Ladich ([EMAIL PROTECTED]) gave me the following literature hints:
i)
Karlsen H. E. [1992] "Infrasound sensitivity in the plaice (Pleuronectes
platessa) J.
Exp. Biol. 171, 173-187; ii) Karlsen H. E. [1992]: "The inner ear is
responsible for
detection of infrasound in the perch (Perca fluvialis) J. Exp. Zool. 171;
163-172;
iii) Sand O.. and Karlsen H. E. "Detection of infrasound and linear
acceleration in
fishes" [2000] 355 1295-1298; iiii) Sand O. and Karlsen H. E. "Detection of
infrasound
by the Atlantic cod" J. Exp. Biol. 1986; 125, 197-204. These papers show that
(rather
small) fishes are, indeed, sensitive to infrasonic sound.
* Oluf Damsgaard Henriksen ([EMAIL PROTECTED]) confirmed that the literature
does not
give definitive answers, yet, to the question whether or not small marine
mammals are
sensitive to infrasonic noise. Interesting to me was that he wrote about
several
investigations on the reaction of harbour porpoises and harbour seals to wind
turbine
noise. Indeed, they react. However, it is still to be clarified.which parts of
the
whole sound spectrum are responsible for the reactions. The investigations
mentioned
were made in Danmark. - Oluf Damsgaard Henriksen is also one of the authors
(Tougaard,J.,Carstensen, J.,Henriksen,O.D.,Skov,H.. and Teimann,J. [2003] ) of
the
Technical Report to Techwise A/S HME/362-02662, Hedeselskabet,Roskilde called
"Short-term effects of the construction of wind turbines on harbour porpoises
at Horns
Reef". In that report the authors describe changes in abundance and behaviour
of
porpoises at a distance of 10 - 15 kilometres from a place at which windpower
mo!
nopiles were rammed into the seabed.
* One further colleague commented but asked for secrecy. So I can merely
respond to
his arguments in an abstract form here.
CONCLUSIONS: Which conclusions are to be drawn from the contributions
mentioned above?
- I propose the following:
1) There are no hard facts giving either evidence for the sensitivity or for
the
insensitivity of harbour porpoises to infrasonic noise.
2) There are, however, some weak indications that they could be sensitive. The
fact
that they react to ramming activities in a distance of 10 - 15 kilometres
should be
considered in context with investigations showing that high frequency noise is
much
more absorbed by seawater than deep frequency noise, infrasonic noise, in
particular
(i.e. Dietrich et al. Allgemeine Meereskunde; Gebrueder Borntraeger Verlag,
Berlin
1975; Wille et. al. (1986) "Measurements of wind dependent acoustic
transmission loss
in shallow water under breaking wave conditions" International congress on
acoustics
S. 501 - 508 ). - Monopile ramming is, indeed, very noisy, but due to
absorption after
10 - 15 km only the low frequency parts of the whole spectrum will remain with
remarkable strength. - In that same context the above-mentioned paper of
Wahlberg and
Westerberg is to be read: "Windmills are expected to be detectable by fish at
maximum
ranges of 0,4 - 25 kilometres at wind speeds from 8 - 13 m/s!
". Thereby it remains unclear, which parts of the whole frequency spectrum
are
responsible for the relevant reactions. Nonetheless, considering again the
fact that
the high frequency noise is rapidly absorbed the results can be taken as a
hint which
suggests that deep frequency or even infrasonic noise is responsible and that,
thus,
this issue must not be neglected.
3) The common opinion that large whales only are specialists for deep
frequency noise
and that all the smaller organisms are unable to hear and, thus, to react to
infrasonic noise is obviously not true. As cited above, some fishes,
definitely do
react. In that context also the paper of A. Beulig [ A. Beulig (1982) "Social
and
experimental facts in the responsiveness of sharks to sound" Fl.Sci 45(1):
2-10] is of
interest as it gives evidence for the reaction of sharks to infrasonic noise.
4) In the light of the insufficient state of knowledge, on the one hand, and
of the
fact that large parts of the German Bight will be covered with wind parks
which
amongst others will produce infrasonic noise, on the other hand, further
investigations seem to be necessary.
5) Because of the large size, the large number and the high density of
windparks in
the German Bight one has to take a particularly precautious position to the
possible
effects, which means that not only the production of noise should be
minimized, but
also the production of infrasonic noise. Harsh measures are inadequate. But
the
possibility that infrasonic noise may have adverse effects to the marine
environment
should not be neglected. Technological standards should, therefore, be
developed
reflecting, at least, moderate efforts to minimize the "contamination of the
sea" by
infrasonic noise.
RAMMING: Some considerations should be given to ramming: Although ramming
produces far
more noise than the windmills in action the latter deserve much more
attention. Reason
is that possible adverse effects seem to be limited in space and time in the
case of
ramming. In the case of the windmills, however, we would have permanent
effects. Over
and above, such effects would - after construction of all windparks planned -
be
thousandfold. - Although the windmills in action require more attention the
possible
effects of ramming should not be neglected. As far as I understand the
following
measures are under discussion:
I) Preference for tripods to monopiles: Ramming of monopiles is much more
noisy.
Tripods must only be anchored by three comparably small stakes.
II) An air bubble curtain: It is said to absorb noise to a considerable
degree.
III) Installation of pingers to scare away porpoises before ramming
IV) A ramming up phase before actual ramming, which means that ramming is
started with
very low and slowly increasing intensity in order to give animals in the
neighbourhood
a chance to escape.
All the methods are discussed in context with marine mammals. If possible,
however,
other animals should also be protected. I personally feel that we are still in
a
discussion phase. The applicants seem to be willing to use such methods if
their
ecological benefit is obvious and their application constitutes a
technological state
of the art. That is, however, not the case yet.
That's it. Many thanks!
K. - R. Sperling
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