From: "Verfuss Ursula" <[EMAIL PROTECTED]> 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
