322
marine mammals’ populations, because the emission and reception of sound signals
plays a complex and vital role in this populations’ ecology through many different
ways. This study reviews the acoustic repertoire and potential anthropic impacts on
populations of Guiana dolphin (S. guianensis) through its occurrence, and described
and compared the anthropogenic noises with the acoustic repertoire of three Brazilian
populations: Cananéia estuary – São Paulo State, Caravelas estuary – Bahia State and
Pipa beach – Rio Grande do Norte State. Data was collected similarly in these three
sites during boats surveys using hydrophones and audio recorders. Results showed
overlapping of the S. guianensis repertoire and noises produced from boats, dredge
activities and wood-barges, leading to harm on individuals and populations. This
review has gathered important information supporting marine activity management,
and can be used to evaluate acoustic impacts over cetaceans population.
Keywords Sotalia guianensis • Guiana dolphin • Soundscape • Acoustic •
Anthropogenic noise • Cetaceans
13.1 Introduction
Aquatic ecosystems are very sensitive environments, with diversity and abundance
of interdependent organisms. Oceanic, coastal and estuarine areas suffer intense
pressure from anthropogenic activities, therefore the importance of better understanding the impacts in these ecosystems, with the purpose of assisting in the management
guidelines and conservation issues, so that these environments are able to maintain
their natural ecological balance.
Acoustic ecology studies the relationship of sounds between organisms and individuals, and between organisms and the environment (Erbe et al. 2016). The term “noise”
refers to diffuse sounds that don’t provide significant biological information. Sounds
emitted by aquatic mammals are called “acoustic signals”, as they contain specific information. The raising number of sound sources in marine waters, with wide range of
frequencies and intense energy levels, lead to ecosystems with greater ambient noise.
The variability of sound sources results in acoustic environments with singular
characteristics in different space-time scales that are denominated “soundscapes”
(Pijanowski et al. 2011). They can also be interpreted as the acoustic environments
of aquatic ecosystems, composed by sounds of natural (biotic and abiotic) or
anthropic sources. Examples of natural sound sources are: earthquakes, wind, rain,
waves, fishes, shrimps, etc. Anthropic sound sources occur as result of several
human activities, such as: shipping, boat traffic, dredging, wind turbines, sonars, oil
and gas exploitation, port activities and seismic activities (Richardson et al. 1995;
Popper and Hawkins 2016).
Such anthropogenic noise can potentially cause negative impacts on aquatic mammal populations, since the emission and detection of sound signals play a complex and
vital role in their ecology through various aspects, such as group cohesion, individual
recognition, escape from predators, prey detection and reproductive behavior (Stewart
2008; Tyack 2000a, b). Thus, underwater noises are able to prevail over the sounds
emitted by aquatic mammals, becoming a threat for individuals and population.
F. de Sousa Pais et al.
marine mammals’ populations, because the emission and reception of sound signals
plays a complex and vital role in this populations’ ecology through many different
ways. This study reviews the acoustic repertoire and potential anthropic impacts on
populations of Guiana dolphin (S. guianensis) through its occurrence, and described
and compared the anthropogenic noises with the acoustic repertoire of three Brazilian
populations: Cananéia estuary – São Paulo State, Caravelas estuary – Bahia State and
Pipa beach – Rio Grande do Norte State. Data was collected similarly in these three
sites during boats surveys using hydrophones and audio recorders. Results showed
overlapping of the S. guianensis repertoire and noises produced from boats, dredge
activities and wood-barges, leading to harm on individuals and populations. This
review has gathered important information supporting marine activity management,
and can be used to evaluate acoustic impacts over cetaceans population.
Keywords Sotalia guianensis • Guiana dolphin • Soundscape • Acoustic •
Anthropogenic noise • Cetaceans
13.1 Introduction
Aquatic ecosystems are very sensitive environments, with diversity and abundance
of interdependent organisms. Oceanic, coastal and estuarine areas suffer intense
pressure from anthropogenic activities, therefore the importance of better understanding the impacts in these ecosystems, with the purpose of assisting in the management
guidelines and conservation issues, so that these environments are able to maintain
their natural ecological balance.
Acoustic ecology studies the relationship of sounds between organisms and individuals, and between organisms and the environment (Erbe et al. 2016). The term “noise”
refers to diffuse sounds that don’t provide significant biological information. Sounds
emitted by aquatic mammals are called “acoustic signals”, as they contain specific information. The raising number of sound sources in marine waters, with wide range of
frequencies and intense energy levels, lead to ecosystems with greater ambient noise.
The variability of sound sources results in acoustic environments with singular
characteristics in different space-time scales that are denominated “soundscapes”
(Pijanowski et al. 2011). They can also be interpreted as the acoustic environments
of aquatic ecosystems, composed by sounds of natural (biotic and abiotic) or
anthropic sources. Examples of natural sound sources are: earthquakes, wind, rain,
waves, fishes, shrimps, etc. Anthropic sound sources occur as result of several
human activities, such as: shipping, boat traffic, dredging, wind turbines, sonars, oil
and gas exploitation, port activities and seismic activities (Richardson et al. 1995;
Popper and Hawkins 2016).
Such anthropogenic noise can potentially cause negative impacts on aquatic mammal populations, since the emission and detection of sound signals play a complex and
vital role in their ecology through various aspects, such as group cohesion, individual
recognition, escape from predators, prey detection and reproductive behavior (Stewart
2008; Tyack 2000a, b). Thus, underwater noises are able to prevail over the sounds
emitted by aquatic mammals, becoming a threat for individuals and population.
F. de Sousa Pais et al.