479
guianesis, the Guiana dolphin (Delphinidae) in the southwestern Atlantic Ocean.
These species are sympatric over much their ranges along the Brazilian coast, which
extends from the southern limit of Guiana dolphin distribution in Florianópolis,
Santa Catarina (27°23′S; 48°33′W) (Simões-Lopes 1988), to the northern limit of
distribution of the franciscana dolphin in Itaúnas, Espírito Santo (18°25′S; 30°42′W)
(Moreira and Siciliano 1991). Guiana dolphins commonly occupy bays and inlets
throughout their species range (Pizzorno 1999; Flores 1999; Geise et al. 1999;
Edwards and Schnell 2001; Lodi 2003), which extends north to Nicaragua (14°35′N,
83°14′W) (Carr and Bonde 2000), and includes Babitonga Bay (Hardt et al. 2010).
Franciscana dolphin distribution extends southward to the Golfo Nuevo in Argentina
(42°35′S; 64°48′W) (Crespo et al. 1998), and Babitonga Bay is the only estuarine
bay in which this species occurs throughout the year (Cremer and Simões-Lopes
2005). These two dolphin species live in direct sympatry in Babitonga Bay (sensu
Bearzi 2005), i.e., they co-occur in the same immediate habitat.
The first cetacean surveys in Babitonga Bay took place in 1995. Guiana dolphins
are well-known to occupy bays and estuaries in southern Brazil, and this knowledge
combined with reports from the local community led to a consensus that they were
likely the only species in Babitonga Bay. However, in late 1996 researchers discovered a franciscana dolphin population in the bay (IBAMA 1998). Local fishermen
also had prior knowledge of franciscana dolphins in the area, but there is no available information on how long either species have been residing there.
Various efforts have been made to better understand the ecology and behavior of
both dolphin species. Following is a review of the knowledge of franciscana and
Guiana dolphins in Babitonga Bay, derived from abstracts, papers, books, monographs, dissertations, theses, and reports published over the last 20 years.
17.2 Babitonga Bay
Babitonga Bay lies on the northern coast of Santa Catarina state in southern Brazil
(26°02′ – 26°28′S, 48°28′ – 48°50′W). The bay contains the last remaining major
mangrove habitat in the southern hemisphere (IBAMA 1998) (Fig. 17.1). This subtropical estuary has an area of 160 km
2
, with many islands, rivers, sand banks, and
rock formations. The tide shows a maximum range of 2.3 m. Mean bay depth is
roughly 6 m, with a deeper entrance channel that can reach 25 m. The bay margins
are composed mainly of mangrove forest, but also contain sandy-muddy beaches
and rocks.
Despite the importance of this ecosystem and high species richness, the area has
been suffering anthropogenic effects of extensive human occupation of surrounding
areas. In 2010, there were 620.572 inhabitants among the six municipalities surrounding the bay (IBGE 2010). Detrimental human activities include water pollution, intense boat traffic, port activity, and illegal occupation of mangrove areas,
among others; these issues present major challenges for conservation. The bay has
two large harbors, and also hosts various economic activities such as fishing, sand
17 Behavior and Ecology of Endangered Species Living Together: Long-Term…
guianesis, the Guiana dolphin (Delphinidae) in the southwestern Atlantic Ocean.
These species are sympatric over much their ranges along the Brazilian coast, which
extends from the southern limit of Guiana dolphin distribution in Florianópolis,
Santa Catarina (27°23′S; 48°33′W) (Simões-Lopes 1988), to the northern limit of
distribution of the franciscana dolphin in Itaúnas, Espírito Santo (18°25′S; 30°42′W)
(Moreira and Siciliano 1991). Guiana dolphins commonly occupy bays and inlets
throughout their species range (Pizzorno 1999; Flores 1999; Geise et al. 1999;
Edwards and Schnell 2001; Lodi 2003), which extends north to Nicaragua (14°35′N,
83°14′W) (Carr and Bonde 2000), and includes Babitonga Bay (Hardt et al. 2010).
Franciscana dolphin distribution extends southward to the Golfo Nuevo in Argentina
(42°35′S; 64°48′W) (Crespo et al. 1998), and Babitonga Bay is the only estuarine
bay in which this species occurs throughout the year (Cremer and Simões-Lopes
2005). These two dolphin species live in direct sympatry in Babitonga Bay (sensu
Bearzi 2005), i.e., they co-occur in the same immediate habitat.
The first cetacean surveys in Babitonga Bay took place in 1995. Guiana dolphins
are well-known to occupy bays and estuaries in southern Brazil, and this knowledge
combined with reports from the local community led to a consensus that they were
likely the only species in Babitonga Bay. However, in late 1996 researchers discovered a franciscana dolphin population in the bay (IBAMA 1998). Local fishermen
also had prior knowledge of franciscana dolphins in the area, but there is no available information on how long either species have been residing there.
Various efforts have been made to better understand the ecology and behavior of
both dolphin species. Following is a review of the knowledge of franciscana and
Guiana dolphins in Babitonga Bay, derived from abstracts, papers, books, monographs, dissertations, theses, and reports published over the last 20 years.
17.2 Babitonga Bay
Babitonga Bay lies on the northern coast of Santa Catarina state in southern Brazil
(26°02′ – 26°28′S, 48°28′ – 48°50′W). The bay contains the last remaining major
mangrove habitat in the southern hemisphere (IBAMA 1998) (Fig. 17.1). This subtropical estuary has an area of 160 km
2
, with many islands, rivers, sand banks, and
rock formations. The tide shows a maximum range of 2.3 m. Mean bay depth is
roughly 6 m, with a deeper entrance channel that can reach 25 m. The bay margins
are composed mainly of mangrove forest, but also contain sandy-muddy beaches
and rocks.
Despite the importance of this ecosystem and high species richness, the area has
been suffering anthropogenic effects of extensive human occupation of surrounding
areas. In 2010, there were 620.572 inhabitants among the six municipalities surrounding the bay (IBGE 2010). Detrimental human activities include water pollution, intense boat traffic, port activity, and illegal occupation of mangrove areas,
among others; these issues present major challenges for conservation. The bay has
two large harbors, and also hosts various economic activities such as fishing, sand
17 Behavior and Ecology of Endangered Species Living Together: Long-Term…