@article {58417,
	title = {Limited vocal compensation for elevated ambient noise in bearded seals: implications for an industrializing Arctic Ocean},
	year = {2021},
	abstract = {<p>Vocalizing animals have several strategies to compensate for elevated ambient noise. These behaviours evolved under historical conditions, but compensation limits are quickly being reached in the Anthropocene. Acoustic communication is essential to male bearded seals that vocalize for courtship and defending territories. As Arctic sea ice declines, industrial activities and associated anthropogenic noise are likely to increase. Documenting how seals respond to noise and identifying naturally occurring behavioural thresholds would indicate either their resilience or vulnerability to changing soundscapes. We investigated whether male bearded seals modified call amplitudes in response to changing ambient noise levels. Vocalizing seals increased their call amplitudes until ambient noise levels reached an observable threshold, above which call source levels stopped increasing. The presence of a threshold indicates limited noise compensation for seals, which still renders them vulnerable to acoustic masking of vocal signals. This behavioural threshold and response to noise is critical for developing management plans for an industrializing Arctic.</p>
},
	keywords = {bearded seal advertisement, changing Arctic, Lombard effect, noise impacts},
	doi = {10.1098/rspb.2020.2712},
	url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2712},
	author = {Fournet, Michelle E. H. and Silvestri, Margherita and Clark, Christopher W. and Klinck, Holger and Rice, Aaron N.}
}
@article {58197,
	title = {Acoustically advertising male harbour seals in southeast Alaska do not make biologically relevant acoustic adjustments in the presence of vessel noise},
	year = {2020},
	abstract = {<p>Aquatically breeding harbour seal (Phoca vitulina) males use underwater vocalizations during the breeding season to establish underwater territories, defend territories against intruder males, and possibly to attract females. Vessel noise overlaps in frequency with these vocalizations and could negatively impact breeding success by limiting communication space. In this study, we investigated whether harbour seals employed anti-masking strategies to maintain communication in the presence of vessel noise in Glacier Bay National Park and Preserve, Alaska. Harbour seals in this location did not sufficiently adjust source levels or acoustic parameters of vocalizations to compensate for acoustic masking. Instead, for every 1 dB increase in ambient noise, signal excess decreased by 0.84 dB, indicating a reduction in communication space when vessels passed. We suggest that harbour seals may already be acoustically advertising at or near a biologically maximal sound level and therefore lack the ability to increase call amplitude to adjust to changes in their acoustic environment. This may have significant implications for this aquatically breeding pinniped, particularly for populations in high noise regions.</p>
},
	keywords = {acoustic communication, harbour seals, marine mammals, Noise, vocalizations},
	doi = {10.1098/rsbl.2019.0795},
	url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2019.0795},
	author = {Matthews, Leanna P. and Fournet, Michelle E. H. and Gabriele, Christine and Klinck, Holger and Parks, Susan E.}
}
