Name: Christopher Clark
Address: Bioacoustics Research Program, Cornell Laboratory of Ornithology, 159 Sapsucker Woods Road, Ithaca, New York 14850, USA
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.
Funding for the data presented herein was provided under NOPP-ONR Grant #N00014-07-1-1029 and contracts with Commonwealth of Massachusetts Division of Marine Fisheries, Excelerate Energy and Suez Enery LLC.
Cornell Laboratory of Ornithology, Marine Acoustics, Southall Environmental Associates, University of California Santa Cruz, NOAA, NOAA Fisheries
- To describe acoustic communication masking in the marine environment with focus on the mysticetes
- To introduce the concept of a dynamic spatio-spectral-temporal acoustic habitat to study masking effects of noise
- To formalize a protocol using the sonar equation to quantify the effects of anthropogenic noise in an animal’s acoustic environment
- To formalize a method for quantifying the cumulative effects of co-varying numbers and types of anthropogenic sources
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. The acoustic communication space for the North Atlantic right whale is seriously compromised by noise from commercial shipping traffic.
Clark, C.; Ellison, W.; Southall, B.; Hatch, L.; Van Parijs, S.; Frankel, A.; Ponirakis, D. (2009). Acoustic Masking In Marine Ecosystems: Intuitions, Analysis, And Implication. Marine Ecology Progress Series, 395, 201-222. https://tethys.pnnl.gov/publications/acoustic-masking-marine-ecosystems-intuitions-analysis-and-implication