MEPS 395:201-222 (2009)  -  doi:10.3354/meps08402

Acoustic masking in marine ecosystems: intuitions, analysis, and implication

Christopher W. Clark1,*, William T. Ellison2, Brandon L. Southall3,4, Leila Hatch5, Sofie M. Van Parijs6, Adam Frankel2, Dimitri Ponirakis1

1Bioacoustics Research Program, Cornell Laboratory of Ornithology, 159 Sapsucker Woods Road, Ithaca, New York 14850, USA
2Marine Acoustics, 809 Aquidneck Avenue, Middletown, Rhode Island 02842, USA
3Southall Environmental Associates, 911 Center Street, Suite B, Santa Cruz, California 95060, USA
4Long Marine Laboratory, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, California 95060, USA
5Gerry E. Studds Stellwagen Bank National Marine Sanctuary, NOAA, 175 Edward Foster Road, Scituate, Massachusetts 02066, USA
6 NOAA Fisheries, Northeast Fisheries Science Center, 166 Water Street, Woods Hole, Massachusetts 02543, USA

ABSTRACT: Acoustic masking from anthropogenic noise is increasingly being considered as a threat to marine mammals, particularly low-frequency specialists such as baleen whales. Low-frequency ocean noise has increased in recent decades, often in habitats with seasonally resident populations of marine mammals, raising concerns that noise chronically influences life histories of individuals and populations. In contrast to physical harm from intense anthropogenic sources, which can have acute impacts on individuals, masking from chronic noise sources has been difficult to quantify at individual or population levels, and resulting effects have been even more difficult to assess. This paper presents an analytical paradigm to quantify changes in an animal’s acoustic communication space as a result of spatial, spectral, and temporal changes in background noise, providing a functional definition of communication masking for free-ranging animals and a metric to quantify the potential for communication masking. We use the sonar equation, a combination of modeling and analytical techniques, and measurements from empirical data to calculate time-varying spatial maps of potential communication space for singing fin (Balaenoptera physalus), singing humpback (M. novaeangliae), and calling right (Eubalaena glacialis) whales. These illustrate how the measured loss of communication space as a result of differing levels of noise is converted into a time-varying measure of communication masking. The proposed paradigm and mechanisms for measuring levels of communication masking can be applied to different species, contexts, acoustic habitats and ocean noise scenes to estimate the potential impacts of masking at the individual and population levels.


KEY WORDS: Communication masking · Ambient noise · Acoustic habitat · Communication space · Spatio-temporal variability · Spectral variability · Cumulative effects · Marine mammals · Baleen whales


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Cite this article as: Clark CW, Ellison WT, Southall BL, Hatch L, Van Parijs SM, Frankel A, Ponirakis D (2009) Acoustic masking in marine ecosystems: intuitions, analysis, and implication. Mar Ecol Prog Ser 395:201-222

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