264
manatee, T. m. manatus, including manatees that inhabit the tropical and subtropical
western Atlantic coasts, from Bahamas to Brazil, including the Caribbean Sea and
Gulf of Mexico. However genetic (García-Rodríguez et al. 1998; Vianna et al. 2006;
Santos et al. 2016), skull morphology and cytogenetic (Barros 2013; Barros et al.
2017) studies indicate the necessity to revisit this taxonomic classification.
Therefore, in this chapter we chose not to use the subspecific classification.
The species inhabits exclusively tropical waters of Atlantic Ocean, from Virginia
(37° N, 76° W), in United States, to Alagoas (10° S, 36° W), in Northeastern Brazil,
in a fragmented way. In the United States, West Indian manatee is concentrated in
Florida, due to warm water temperature. During summer months, some animals
disperse to other states and can be found in Georgia, South Carolina, North Carolina,
Virginia and rarely in New Jersey. In tropical countries, the species range is not
totally understood, however it seems more related to displacements from resting
areas to foraging and freshwater sites.
As an exclusively herbivore taxa, manatees occur in rivers, estuaries, lagoons,
channels and coastal shallow waters, where animals can feed on a variety of submerged, floating or emergent plants (Marsh et al. 2011). In the United States, during
winter, animals concentrate in warm water refuges, natural or artificial, with clear
waters. These two factors propitiated early studies with the species there. In other
countries, mainly in South America, low species density and difficulty to detect the
species, that inhabits areas with murky waters, associated with a lower financial
investment in research in the past, lead to a delay in manatee research. In the last
decade, an increase in manatee research could be noted in South America.
Nevertheless, a significant part of this information is available only in theses, conference abstracts, reports, etc. Thus, in this chapter we present a review on the
research conducted with West Indian manatee in South America, discussing its
importance to species conservation and management.
11.2 Distribution
In South America, T. manatus inhabits rivers, swamps, coastal lagoons, estuaries
and coastal areas. Dark waters in these habitats hamper manatee detection, rendering aerial surveys an ineffective method to identify the species distribution. Thus,
indirect evidences, such as interviews, feeding traces and presence of feces are the
most used approaches to study manatees in the region, associated with direct observations. Aerial surveys were only used with good results in Brazil (Alves et al. 2013,
2016). More recently, the side scan sonar (SSS) emerged as an important detection
tool to study manatees (Gonzalez-Socoloske et al. 2009; Gonzalez-Socoloske and
Olivera-Gomez 2012). Detection of manatees using sonars initially aimed to avoid
collision with boats, the main cause of manatee mortality in U.S.A. (eg, Bowles
et al. 2004). However, as demonstrated by Gonzalez-Socoloske et al. (op. cit.)
through tests in clear waters of Florida and in the dark waters of a lagoon in Mexico,
SSS is a cost-effective option to detect manatees in turbid and dark waters. In South
A.C.O. de Meirelles et al.
manatee, T. m. manatus, including manatees that inhabit the tropical and subtropical
western Atlantic coasts, from Bahamas to Brazil, including the Caribbean Sea and
Gulf of Mexico. However genetic (García-Rodríguez et al. 1998; Vianna et al. 2006;
Santos et al. 2016), skull morphology and cytogenetic (Barros 2013; Barros et al.
2017) studies indicate the necessity to revisit this taxonomic classification.
Therefore, in this chapter we chose not to use the subspecific classification.
The species inhabits exclusively tropical waters of Atlantic Ocean, from Virginia
(37° N, 76° W), in United States, to Alagoas (10° S, 36° W), in Northeastern Brazil,
in a fragmented way. In the United States, West Indian manatee is concentrated in
Florida, due to warm water temperature. During summer months, some animals
disperse to other states and can be found in Georgia, South Carolina, North Carolina,
Virginia and rarely in New Jersey. In tropical countries, the species range is not
totally understood, however it seems more related to displacements from resting
areas to foraging and freshwater sites.
As an exclusively herbivore taxa, manatees occur in rivers, estuaries, lagoons,
channels and coastal shallow waters, where animals can feed on a variety of submerged, floating or emergent plants (Marsh et al. 2011). In the United States, during
winter, animals concentrate in warm water refuges, natural or artificial, with clear
waters. These two factors propitiated early studies with the species there. In other
countries, mainly in South America, low species density and difficulty to detect the
species, that inhabits areas with murky waters, associated with a lower financial
investment in research in the past, lead to a delay in manatee research. In the last
decade, an increase in manatee research could be noted in South America.
Nevertheless, a significant part of this information is available only in theses, conference abstracts, reports, etc. Thus, in this chapter we present a review on the
research conducted with West Indian manatee in South America, discussing its
importance to species conservation and management.
11.2 Distribution
In South America, T. manatus inhabits rivers, swamps, coastal lagoons, estuaries
and coastal areas. Dark waters in these habitats hamper manatee detection, rendering aerial surveys an ineffective method to identify the species distribution. Thus,
indirect evidences, such as interviews, feeding traces and presence of feces are the
most used approaches to study manatees in the region, associated with direct observations. Aerial surveys were only used with good results in Brazil (Alves et al. 2013,
2016). More recently, the side scan sonar (SSS) emerged as an important detection
tool to study manatees (Gonzalez-Socoloske et al. 2009; Gonzalez-Socoloske and
Olivera-Gomez 2012). Detection of manatees using sonars initially aimed to avoid
collision with boats, the main cause of manatee mortality in U.S.A. (eg, Bowles
et al. 2004). However, as demonstrated by Gonzalez-Socoloske et al. (op. cit.)
through tests in clear waters of Florida and in the dark waters of a lagoon in Mexico,
SSS is a cost-effective option to detect manatees in turbid and dark waters. In South
A.C.O. de Meirelles et al.