The acoustic Activity of Harbour Porpoises (Phocoena phocoena): Diel Patterns and Potential Influence of Boat noise
2014 (English)Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE credits
Student thesis
Abstract [en]
Sound is of great importance for many marine organisms. Anthropogenic sounds increase globally as a result of an expanded human exploration of aquatic environments. If and how such sounds are affecting wildlife is not fully understood in many cases and therefore an area of concern. For the harbour porpoise (Phocoena phocoena) the use of sounds is vital for its survival. Its coastal distribution, where anthropogenic noise are concentrated, also makes this species exposed to large amount of noise which creates concerns about impacts for this species. To investigate the impact of boat noise on this species, recordings of background noise and acoustic porpoise activity were made at Kullaberg, SW Sweden, during spring and summer of 2013. A significant diel pattern of porpoise activity (PPM) was observed with a peak during evening in spring and during night time in summer. The reason for this diel pattern is proposed to originate from predator-prey interactions between porpoises and herring. No correlation between boat noise and porpoise activity (PPM) was seen when using average broadband received level or maximum sound pressure. However when dividing the boat noise into low frequency (0.1-1 kHz) and high frequency (15-25 kHz) bands, weak correlations was seen in some cases (r2=0.006-0.012). For the low frequency spectra porpoise activity was significantly lower with higher boat noise in location A during daytime and during night time for location B. The higher frequency spectra stated a significantly lower porpoise activity for location A during night time whereas porpoise activity increased with higher noise at higher frequency during night time for location B. The results show that different analysis renders different results and that a spectral analysis should be considered. Weak correlations, in the present data, point to nonexistent or minor startling effects for porpoises to boat noise, but future and more extended studies are needed to better understand how porpoises react to noise created by boats.
Place, publisher, year, edition, pages
2014. , p. 36
Keywords [en]
Anthropogenic noise, C-POD, acoustic logger, porpoise logger, diel variation, passive acoustic monitoring, echolocation
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:hh:diva-24751OAI: oai:DiVA.org:hh-24751DiVA, id: diva2:699795
External cooperation
Syddansk universitet, Länsstyrelsen Skåne
Subject / course
Biology
Supervisors
Examiners
2014-03-042014-02-282014-03-04Bibliographically approved