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ources of sound produced by human activities induce
physical, physiological and behavioral effects on marine
fauna: mammals, reptiles, fish and invertebrates; effects
that can be diverse depending on the proximity to the signal
source. These impacts, for example, include changes in ceta-
cean behaviour and migration routes, and a distinct range
of physical injuries in both marine vertebrates and inverte-
brate. There may be further long-term consequences due
to chronic exposure and sound can indirectly affect animals
due to changes in the accessibility of prey, which may also
suffer the adverse effects of acoustic pollution. These dama-
ges could significantly impair the conservation of species
already endangered which use acoustically contaminated
areas for migratory routes, reproduction and feeding.
For many reasons, evaluating the acoustic impact of artifi-
cial sound sources in the marine environment is a complex
and expensive proposition. Firstly, we face the relative lack
of information on the sound processing and analysis mecha-
nisms in marine organisms. Although we are capable of cata-
loging and recording the majority of these signals, we still
do not know enough about the important role they play in
the balance and development of populations. Secondly, the
possible impact of sound emissions may not only concern
auditory reception systems but might also interfere on other
sensorial and systemic levels, possibly lethal for the affected
animal. Even more complicating the situation is the fact that
a prolonged or punctual exposure to a determined noise can
have negative short, medium and long-term consequences
that are not immediately observed. The lack of provision and
research resources contributes to the greatest difficulty in
obtaining objective data that will allow the efficient control
of anthropogenic noise in the ocean.
In addition, we find ourselves with a most pressing problem,
which relates to the homogenization of measurements. At
the moment, there is no well-defined protocol for measuring
marine acoustic pollution, nor any agreement on the enuncia-
tion of these measurements. While noise effects on the marine
environment are increasing, the variability of the available
parameters to measure these effects leads to heterogeneous
or fragmented results that appear of little use in orientating
preventive and precise management actions (André et al.
Finally, most studies lack information on long-term effects
of noise sources on specific populations. There are very few
data on current ambient noise levels in most regions, and
even less on historical data. Information on trends is not
available for any European waters. According to the Marine
Mammal Commission (MMC 2007), underwater ambient
sound levels will increase over time with more human acti-
vity (shipping, offshore construction) in the marine environ-
ment. It should be further noted that the potential increase
in ambient sound levels will not affect all areas equally but
specific regions where offshore activity is high, for exam-
Cetaceans, bioindicators of noise pollution:
understanding the changes of the marine
Michel André
Laboratoire d’Applications Bioacoustiques (LAB)
Université Polytechnique de Catalogne (UPC)
08800 Vilanova i la Geltrú
E-mail :
Le bruit dans la mer a toujours existé, sous forme naturelle ou biologique. Cependant,
due à son caractère récent et non contrôlé, l’introduction massive de sources sonores
artificielles s’est convertie en une menace pour son équilibre, plus importante que
n’importe quelle autre pollution à laquelle se confronte aujourd’hui le milieu marin.
Les cétacés, prédateurs supérieurs dans la chaîne alimentaire, ont évolué depuis
des millions d’années autour de la perception acoustique de leur environnement
et représentent des bio indicateurs naturels de l’équilibre acoustique des océans.
Comprendre mieux la perception du milieu et les mécanismes de communication
de ces mammifères marins signifie faire de la recherche pour la conservation des
écosystèmes marins et le développement durable des activités humaines en mer.
Ocean noise has always existed, both in natural and biological forms. Without any
doubt, due to its recent and uncontrolled character, the massive introduction of artificial
sound sources at a large scale has become a threat to its balance, more importantly
than any other pollution found in the marine environment. Cetaceans, as top predators
of the food chain, have evolved for millions of years on their acoustic perception of
the environment and can be considered as bio-indicators of the acoustic balance in
the oceans. Understanding how marine mammals perceive their environment and
unravelling their communication methods means investigating for the conservation of
the marine ecosystems and the development of sustainable human activities in the sea.