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Cetaceans, bioindicators of noise pollution: understanding the changes of the marine environment
Another peculiarity along with the absence of vocal chords,
also unique in mammals, is the non-use of the external audi-
tory channel for hearing purposes. Auditory vibrations are
received across fatty tissues situated at lower jaw level
that direct information to the middle and inner ear where
it is processed before arriving to the brain.
Best Practices in management, assessment,
and control of underwater noise pollution
Based on the above and before addressing activities that can
cause noise pollution in the sea, within the framework of its
authorization system (Environmental Impact Assessment),
or by mean of its introduction in management systems of
Marine Protected Areas, it is important to carry forth the
following activities :
- Noise pollution measurements that the activity might
provoke, like Sound Pressure Levels, Equivalent Sound
Level (Leq), Sound Exposure Level (SEL), Energy Flux
Density and Power Spectral Density.
- Comparison of results obtained from the measurements
with tolerance thresholds of the different species present in
the area, according to currently available scientific data.
- Description of the need to adopt some of the reduction
measurements of the sound source.
- Description of the need to adopt some of the mitigation
measurements from the produced impact.
Once the activity is authorized (in its case with its reduc-
tion or mitigation Measurements), the following must be
adopted and implemented :
- Monitoring systems by means of sound propagation
modeling and acoustic cartography.
- Monitoring by means of Passive Acoustic Monitoring
Special attention will be paid to the necessity of addres-
sing the following within the monitoring framework of the
activity :
4- Even though the range of frequencies embrace a considerable bandwidth that
makes classification in different groups difficult, we consider here the central
energy to the auditory spectrum of the species studied.
- The electrophysiological examination of stranded indivi-
duals in order to reveal the different acoustic sensitivities
of different species (Auditory Evoked Potentials, AEP).
- The postmortem study of acoustic reception channels
to establish possible injuries related to artificial sound
source exposure.
- Comparative postmortem study of injuries in non-audi-
tory organs.
[1] André, M., Morell, M., Mas, A., Solé, M., van der Schaar, M., Houégnigan,
L., Zaugg, S., Castell, J.V., Baquerizo, C. and Rodríguez Roch, L. 2010.
Best practices in management, Assessment and control of underwater noise
pollution. Laboratory of Applied Bioacoustics, Technical University of Barcelona,
CONAT150113NS2008029. 105pp. Available from
[2] Boyd, I., R. Brownell, D. Cato, Chris Clark, D.P. Costa, P. Evans, J. Gedamke,
R. Gentry, R. Gisiner, J. Gordon, P. Jepson, P. Miller, L. Rendell, M. Tasker, P.
Tyack, E. Vos, H. Whitehead, D. Wartzok, W. Zimmer. 2008. The effects of
anthropogenic sound on marine mammals: A draft research strategy.  European
Science Foundation Marine Board Position Paper 13. 24 pp.
Functional groups
according to auditory
Genus represented
Low frequency
7Hz to 22 kHz Baleana, Caperea, Eschrichtius, Megaptera, Balaenptera (13 species/subspecies)
Mid frequency
150 Hz
to 160 kHz
Steno, Sousa, Tursiops, Stenella, Delphinus, Lagenodelphis, Lagenorhynchus, Lissodelphis,
Grampus, Peponocephala, Feresa, Pseudorca, Orcinus, Globicephala, Orcaella, Physeter,
Delphinapterus, Monodon, Ziphius, Berardius, Tasmacetus, Hyperoodon, Mesoplodon (57
High Frequency
200 Hz
to 180 kHz
Phocoena, Neophocaena,Phocoenoides, Plaanista, Inia, Kogia, Lipotes, Pontoporia,
Cephalorhynchus (20 species/subspecies)
Table 2 : Functional groups according to the auditory characteristics of cetaceans, the estimated bandwidth and the genus
that represents each group