351
of higher frequencies in noisy environments (Heiler et al. 2016) and may have wide
variation on its tones and longer duration when compared to the environment with
only one boat (May-Collado and Wartzok 2008), confirming the results obtained by
Martins et al. (2016) to the Guiana dolphin in Pipa beach.
Studies with killer whales (Orcinus orca) have also showed changes in vocalizations, increasing the intensity of signals with increasing noise caused by boats,
which can have as a consequence a greater energy expenditure, higher stress level
and also an inefficient communication between individuals, may affect then other
activities (for example, reproduction and socialization) (Holt et al. 2009).
May-Collado and Quiñones-Lebrón (2014) in a study comparing changes in the
acoustic repertoire of bottlenose dolphins with the presence of small boats concluded that such changes vary according to the behavior of animals. It was described
that when the dolphins were in social interactions or swimming, in the presence of
boats, the acoustic parameters showed no significant change, while when the activity was foraging, showed a reduction on the frequencies and the signals duration has
increased.
Whereas the main activity described for S. guianensis in the three areas of study
described in this paper (Cananéia estuary, Caravelas estuary and Pipa beach) is the
foraging activity, we can suggest a high sensitivity of the animals to the presence of
the vessel generated noise, especially petrol engines ones, indicating a high potential of impact over the three populations studied.
A study about the economic value of the Guiana dolphin observation tours in
Cananéia estuary came to the conclusion that this is an activity of great importance
in the income of the community (Filla et al. 2012), similarly as in Pipa beach, a
region that presents a fast growth of this kind of tourism, also reflecting the local
economy.
The Guiana dolphin watching tourism is a rising activity both in the estuary of
Cananéia and in Pipa beach. For the activity to prosper it must be carried out in a
sustainable manner. The sustainability depends basically on management of visitors
(respecting the carrying capacity of visitors in each region), fluctuations in the local
and regional economy, and especially the maintenance of the resource or species,
which is the target of the tourism (Sousa-Lima and Clark 2008).
Filla and Monteiro-Filho (2009) showed that the Guiana dolphins of Cananéia
estuary have different responses according to the approaching of tourist boats.
When boats proceeded properly, behavioral responses were positive (the animals
approached the boat, swam around, followed the boat or foraged, for example) or
neutral (continued their activity) (Fig. 13.26). In 100% of approaches considered
inadequate, the results were negative reactions from animals, such as abandonment
of activity, group separation, diving in different directions and evacuation of the
area (Filla and Monteiro-Filho 2009).
Albuquerque and Souto (2013) showed that in 54% of the time that the Guiana
dolphins were using the area of the Baía dos Golfinhos (Pipa beach, Rio Grande do
Norte state) boats were present, and in 95% of cases the vessels approached in a
distance less than 50 m away from the animals (Fig. 13.27).
13 Anthropogenic Noise and Guiana Dolphins (Sotalia guianensis) in Brazil…
of higher frequencies in noisy environments (Heiler et al. 2016) and may have wide
variation on its tones and longer duration when compared to the environment with
only one boat (May-Collado and Wartzok 2008), confirming the results obtained by
Martins et al. (2016) to the Guiana dolphin in Pipa beach.
Studies with killer whales (Orcinus orca) have also showed changes in vocalizations, increasing the intensity of signals with increasing noise caused by boats,
which can have as a consequence a greater energy expenditure, higher stress level
and also an inefficient communication between individuals, may affect then other
activities (for example, reproduction and socialization) (Holt et al. 2009).
May-Collado and Quiñones-Lebrón (2014) in a study comparing changes in the
acoustic repertoire of bottlenose dolphins with the presence of small boats concluded that such changes vary according to the behavior of animals. It was described
that when the dolphins were in social interactions or swimming, in the presence of
boats, the acoustic parameters showed no significant change, while when the activity was foraging, showed a reduction on the frequencies and the signals duration has
increased.
Whereas the main activity described for S. guianensis in the three areas of study
described in this paper (Cananéia estuary, Caravelas estuary and Pipa beach) is the
foraging activity, we can suggest a high sensitivity of the animals to the presence of
the vessel generated noise, especially petrol engines ones, indicating a high potential of impact over the three populations studied.
A study about the economic value of the Guiana dolphin observation tours in
Cananéia estuary came to the conclusion that this is an activity of great importance
in the income of the community (Filla et al. 2012), similarly as in Pipa beach, a
region that presents a fast growth of this kind of tourism, also reflecting the local
economy.
The Guiana dolphin watching tourism is a rising activity both in the estuary of
Cananéia and in Pipa beach. For the activity to prosper it must be carried out in a
sustainable manner. The sustainability depends basically on management of visitors
(respecting the carrying capacity of visitors in each region), fluctuations in the local
and regional economy, and especially the maintenance of the resource or species,
which is the target of the tourism (Sousa-Lima and Clark 2008).
Filla and Monteiro-Filho (2009) showed that the Guiana dolphins of Cananéia
estuary have different responses according to the approaching of tourist boats.
When boats proceeded properly, behavioral responses were positive (the animals
approached the boat, swam around, followed the boat or foraged, for example) or
neutral (continued their activity) (Fig. 13.26). In 100% of approaches considered
inadequate, the results were negative reactions from animals, such as abandonment
of activity, group separation, diving in different directions and evacuation of the
area (Filla and Monteiro-Filho 2009).
Albuquerque and Souto (2013) showed that in 54% of the time that the Guiana
dolphins were using the area of the Baía dos Golfinhos (Pipa beach, Rio Grande do
Norte state) boats were present, and in 95% of cases the vessels approached in a
distance less than 50 m away from the animals (Fig. 13.27).
13 Anthropogenic Noise and Guiana Dolphins (Sotalia guianensis) in Brazil…