[MARMAM] New publication: Recreational vessels without Automatic Identification System (AIS) dominate anthropogenic noise contributions to a shallow water soundscape (Hermannsen et al. 2019)
Dear all, We are happy to announce that the following paper is now published in Scientific Reports: Hermannsen, L., Mikkelsen, L., Tougaard, J., Beedholm, K., Johnson, M. and P.T. Madsen, “*Recreational vessels without Automatic Identification System (AIS) dominate anthropogenic noise contributions to a shallow water soundscape*”, Scientific Reports (2019) 9:15.477. In this paper, we conduct a case study correlating vessel presence to ambient noise levels in a shallow coastal area. The results show that recreational boats without AIS dominate the soundscape, including at frequencies that may impact harbour porpoises. We therefore emphasise the importance of accounting for recreational boats, in particular in shallow coastal waters, to not underestimate vessel noise loads and the impacts on marine species. To accompany this paper and to help improve models of vessel noise emissions, we have also published the recordings and theodolite tracks of 46 motorised recreational boats, divided into different boat types at zenodo.org (10.5281/zenodo.3465461). *Abstract* Recreational boating is an increasing activity in coastal areas and its spatiotemporal overlap with key habitats of marine species pose a risk for negative noise impacts. Yet, recreational vessels are currently unaccounted for in vessel noise models using Automatic Identification System (AIS) data. Here we conduct a case study investigating noise contributions from vessels with and without AIS (non-AIS) in a shallow coastal area within the Inner Danish waters. By tracking vessels with theodolite and AIS, while recording ambient noise levels, we find that non-AIS vessels have a higher occurrence (83%) than AIS vessels, and that motorised recreational vessels can elevate third-octave band noise centred at 0.125, 2 and 16 kHz by 47–51 dB. Accordingly, these vessels dominated the soundscape in the study site due to their high numbers, high speeds and proximity to the coast. Furthermore, recreational vessels caused 49–85% of noise events potentially eliciting behavioural responses in harbour porpoises (AIS vessels caused 5–24%). We therefore conclude that AIS data would poorly predict vessel noise pollution and its impacts in this and other similar marine environments. We suggest to improve vessel noise models and impact assessments by requiring that faster and more powerful recreational vessels carry AIS-transmitters. *Link to full text*: www.nature.com/articles/s41598-019-51222-9 Best regards, Line *Line Hermannsen, PhD* Postdoctoral fellow at Department of Bioscience, Aarhus University, Denmark Phone: (+45) 22 82 56 61 Email: l...@bios.au.dk www.marinebioacoustics.com ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New Publication: Airgun Pulses in Shallow Water with Implications for Effects on Small Marine Mammals
Dear MARMAMers, We are pleased to announce the publication of the following paper in PLOS ONE: *Characteristics and Propagation of Airgun Pulses in Shallow Water with Implications for Effects on Small Marine Mammals* Hermannsen, L., Tougaard, J., Beedholm, K., Nabe-Nielsen, J. and Madsen P.T. PLOS ONE, July 27, 2015.URL: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0133436 DOI: 10.1371/journal.pone.0133436 AbstractAirguns used in seismic surveys are among the most prevalent and powerful anthropogenic noise sources in marine habitats. They are designed to produce most energy below 100 Hz, but the pulses have also been reported to contain medium-to-high frequency components with the potential to affect small marine mammals, which have their best hearing sensitivity at higher frequencies. In shallow water environments, inhabited by many of such species, the impact of airgun noise may be particularly challenging to assess due to complex propagation conditions. To alleviate the current lack of knowledge on the characteristics and propagation of airgun pulses in shallow water with implications for effects on small marine mammals, we recorded pulses from a single airgun with three operating volumes (10 in3, 25 in3 and 40 in3) at six ranges (6, 120, 200, 400, 800 and 1300 m) in a uniform shallow water habitat using two calibrated Reson 4014 hydrophones and four DSG-Ocean acoustic data recorders. We show that airgun pulses in this shallow habitat propagated out to 1300 meters in a way that can be approximated by a 18log(r) geometric transmission loss model, but with a high pass filter effect from the shallow water depth. Source levels were back-calculated to 192 dB re µPa2s (sound exposure level) and 200 dB re 1 µPa dB Leq-fast (rms over 125 ms duration), and the pulses contained substantial energy up to 10 kHz, even at the furthest recording station at 1300 meters. We conclude that the risk of causing hearing damage when using single airguns in shallow waters is small for both pinnipeds and porpoises. However, there is substantial potential for significant behavioral responses out to several km from the airgun, well beyond the commonly used shut-down zone of 500 meters. For those interested in reading more, this paper and other interesting papers from our Marine Bioacoustics Lab can be downloaded from: www.marinebioacoustics.com/pub.php Best regards,Line Hermannsen -- *Line Hermannsen* *Department of Bioscience* *Aarhus University* *mail: line.hermann...@gmail.com line.hermann...@gmail.com or l...@bios.au.dk l...@bios.au.dk* *telephone: +45 22 82 56 61 %2B45%2022%2082%2056%2061* ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication on high frequency ship noise and potential effects on small toothed whales
Dear MARMAMers, For those interested, we wish to draw attention to a recent paper in the Journal of the Acoustical Society of America on high frequency ship noise and the potential effects on small toothed whales. We show that a broad range of vessel types produce substantial levels of noise at high frequencies, and that smaller toothed whales therefore must be considered in impact assessments of ship noise. We also show that low frequency noise bands are poor proxies for noise loads at higher frequencies, and that current low frequency indicators, such as those in the European Marine Strategy Framework Directive (MSFD), are insufficient when it comes to assessing noise effects on small toothed whales. *High frequency components of ship noise in shallow water with a discussion of implications for harbor porpoises (Phocoena phocoena)* Line Hermannsen, Kristian Beedholm, Jakob Tougaard and Peter T. Madsen J. Acoust. Soc. Am. 136, 1640 (2014) URL: *http://scitation.aip.org/content/asa/journal/jasa/136/4/10.1121/1.4893908 http://scitation.aip.org/content/asa/journal/jasa/136/4/10.1121/1.4893908* DOI: http://dx.doi.org/10.1121/1.4893908 *Full abstract* Growing ship traffic worldwide has led to increased vessel noise with possible negative impacts on marine life. Most research has focused on low frequency components of ship noise, but for high-frequency specialists, such as the harbor porpoise (Phocoena phocoena), medium-to-high frequency noise components are likely more of a concern. To test for biologically relevant levels of medium-to-high frequency vessel noise, different types of Automatic Identification System located vessels were recorded using a broadband recording system in four heavily ship-trafficked marine habitats in Denmark. Vessel noise from a range of different ship types substantially elevated ambient noise levels across the entire recording band from 0.025 to 160 kHz at ranges between 60 and 1000 m. These ship noise levels are estimated to cause hearing range reduction of 20 dB (at 1 and 10 kHz) from ships passing at distances of 1190 m and 30 dB reduction (at 125 kHz) from ships at distances of 490 m or less. It is concluded that a diverse range of vessels produce substantial noise at high frequencies, where toothed whale hearing is most sensitive, and that vessel noise should be considered over a broad frequency range, when assessing noise effects on porpoises and other small toothed whales. A pdf version of the paper can be requested from line.hermann...@gmail.com Best regards, Line Hermannsen ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
