276
In the states of Ceará and Rio Grande do Norte, a monitoring project related to
federal environmental licensing process conducted by IBAMA estimated manatee
abundance through linear transects in aerial surveys from Aquiraz (CE) to Touros
(RN) (387 km) (Petrobras 2014). Distance sampling estimated 193 manatees in the
area (CI 95%: 93–378).
11.5 Feeding
The manatee is an exclusively herbivorous animal. As the species may occur in a
wide variety of habitats, such as marine, freshwater and estuarine environments, the
animals feed on a variety of plants, which may be submerged, floating or emergent,
and the choice between these types will depend on the availability and nutritional
value of each (Marsh et al. 2011).
Trichechus manatus feeding preference is related to species availability, nutritional value, and palatability (Hartman 1979; Best 1981). In South America, the
species inhabits a variety of habitats, as rivers, swamps, estuaries and coastal areas.
Thus, in each of these habitats animals’ diet varies. In Table 11.1, a review on manatee diet in the continent is presented.
An interesting fact when observing the table is the restriction in terms of items
quantity in some areas of Brazil, as the states of Ceará and Alagoas, where manatees
eat basically Halodule wrightii as it has a higher nutritional value than algae
(Meirelles et al. 2016a). This fact is alarming, since impact on seagrass meadows
can severely affect manatees inhabiting these areas.
11.6 Genetics
Garcia-Rodriguez et al. (1998) compared the mitochondrial DNA control region
among eight locations across the western Atlantic Ocean, from Florida to Brazil.
Low levels of genetic diversity were observed in Florida and Brazil (at the limits of
species’ range). Also, the study indicated three mtDNA lineages: Florida and West
Indies; from the Gulf of Mexico to the Caribbean rivers of South America; and
northeastern Atlantic coast of South America. With a larger sample, Vianna et al.
(2006) corroborated these findings. According to Santos et al. (2016), through
mtDNA Bayesian phylogeny and chronological calibration with sirenian fossils,
separation time between manatee populations from the northern Atlantic region and
for those of Caribeean and Gulf of Mexico was estimated in 590,000 years.
Recently, a detailed karyotype analysis revealed differences between chromosomal pair 4 and 10 from T. manatus from Brazil and those from Puerto Rico and
Caribbean (Barros 2013; Barros et al. 2017). The same authors studied 3D geometric morphometrics of manatee skulls and identified important differences between
A.C.O. de Meirelles et al.
In the states of Ceará and Rio Grande do Norte, a monitoring project related to
federal environmental licensing process conducted by IBAMA estimated manatee
abundance through linear transects in aerial surveys from Aquiraz (CE) to Touros
(RN) (387 km) (Petrobras 2014). Distance sampling estimated 193 manatees in the
area (CI 95%: 93–378).
11.5 Feeding
The manatee is an exclusively herbivorous animal. As the species may occur in a
wide variety of habitats, such as marine, freshwater and estuarine environments, the
animals feed on a variety of plants, which may be submerged, floating or emergent,
and the choice between these types will depend on the availability and nutritional
value of each (Marsh et al. 2011).
Trichechus manatus feeding preference is related to species availability, nutritional value, and palatability (Hartman 1979; Best 1981). In South America, the
species inhabits a variety of habitats, as rivers, swamps, estuaries and coastal areas.
Thus, in each of these habitats animals’ diet varies. In Table 11.1, a review on manatee diet in the continent is presented.
An interesting fact when observing the table is the restriction in terms of items
quantity in some areas of Brazil, as the states of Ceará and Alagoas, where manatees
eat basically Halodule wrightii as it has a higher nutritional value than algae
(Meirelles et al. 2016a). This fact is alarming, since impact on seagrass meadows
can severely affect manatees inhabiting these areas.
11.6 Genetics
Garcia-Rodriguez et al. (1998) compared the mitochondrial DNA control region
among eight locations across the western Atlantic Ocean, from Florida to Brazil.
Low levels of genetic diversity were observed in Florida and Brazil (at the limits of
species’ range). Also, the study indicated three mtDNA lineages: Florida and West
Indies; from the Gulf of Mexico to the Caribbean rivers of South America; and
northeastern Atlantic coast of South America. With a larger sample, Vianna et al.
(2006) corroborated these findings. According to Santos et al. (2016), through
mtDNA Bayesian phylogeny and chronological calibration with sirenian fossils,
separation time between manatee populations from the northern Atlantic region and
for those of Caribeean and Gulf of Mexico was estimated in 590,000 years.
Recently, a detailed karyotype analysis revealed differences between chromosomal pair 4 and 10 from T. manatus from Brazil and those from Puerto Rico and
Caribbean (Barros 2013; Barros et al. 2017). The same authors studied 3D geometric morphometrics of manatee skulls and identified important differences between
A.C.O. de Meirelles et al.