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Luna, Fábia de Oliveira; Bonde, Robert K.; Attademo, Fernanda L. N.; Saunders, Jonathan W.; Meigs-Friend, Gaia; Passavante, José Zanon O.; Hunter, Margaret E.
(detail)
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2012 |
Phylogeographic implications for release of critically endangered manatee calves rescued in northeast Brazil.
Aquatic Conserv.: Mar. Freshw. Ecosyst. 22(5): 665–672. 2 tabs. 1 fig. DOI: 10.1002/aqc.2260 Publ. online July 4, 2012 in wileyonlinelibrary.com.
–ABSTRACT: 1. The Antillean manatee (Trichechus manatus manatus), a subspecies of the West Indian manatee, is a large-bodied marine mammal found in fresh, brackish, and marine habitats throughout the Caribbean Islands and Central and South America. Antillean manatees in Brazil are classified as critically endangered, with a census size of approximately 500 individuals. The population in the Northeast region of Brazil is suspected to have approximately 300 manatees and is threatened by habitat alteration and incidental entanglement in fishing gear.
2. A high incidence of dependent calf strandings have been identified near areas of altered critical manatee habitat. The majority of the calves are neonates, discovered alive, with no potential mothers nearby. These calves typically require human intervention to survive.
3. Since 1989 the calves have been rescued (N=67), rehabilitated, and released (N=25) to supplement the small wild manatee population. The rescued calves, and those born in captivity, are typically, not released to their rescue location, mainly for logistical reasons. Therefore, phylogeographic analyses can help to identify related populations and appropriate release sites.
4. Here, mitochondrial DNA analyses identified low haplotype (h=0.08) and nucleotide (p=0.0026) genetic diversity in three closely related haplotypes. All three haplotypes (M01, M03, and a previously unidentified haplotype, M04) were found in the northern portion of the region, while only a single haplotype (M01) was represented in the south. This suggests the presence of two genetic groups with a central mixing zone. Release of rehabilitated calves to unrelated populations may result in genetic swamping of locally adapted alleles or genotypes, limiting the evolutionary potential of the population.
5. The small population size coupled with low genetic diversity indicates that the Northeast Brazil manatee population is susceptible to inbreeding depression and possible local extinction. Further conservation measures incorporating genetic information could be beneficial to the critically endangered Brazilian manatee population.
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de Lima, Régis Pinto; Passavante, José Zanon
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2015 |
Assessment of the first decade (1994-2004) of the West Indian manatee reintroduction (Trichechus manatus) program in the Northeastern coast of Brazil.
Natural Resources 5(1) DOI: 10.6008%2F1147.
–ABSTRACT: Thirteen captive manatees were released and tagged in three different northeastern coastal areas as part of the Brazilian Manatee Reintroduction Program from October 1994 to December 2004. All individuals were monitored locally with VHF transmitters and four were also tracked with satellite tags for different lengths of time. Manatees were tracked from Praia do Forte, Bahia state (12.538ºS/38.474ºW) to Macau, Rio Grande do Norte state (5.084ºS/36.682ºW) along 1200 coastal km of the northeast six states. To evaluate the re-adaptation process was the main objectives of this work, which will hopefully help researchers to make decisions in the future. Two release areas (RA) were beaches with shallow waters, seagrass beds, reefs and close to small rivers; and one was located inside a large estuary with few seagrass beds. Captivity time was not considered in this evaluation but can be an important factor on the success of the manatee reintroduction program. Five manatees occupied home ranges and each contained sites of high fidelity where they spent considerable time. Two manatees were re-captured shortly after release, having moved long distances, including offshore movements into deep waters. Six manatees had few tracked time. Although manatees had few age when released they have found natural conditions for them survival including reproductive behavior. The fidelity sites choose to release manatees in terms of environmental was very similar. A discontinuous occurrence area (RA2) has been used by some released manatees where a first released manatee female had her calf. We strongly recommend: Continuous of this Manatee Reintroduction Program, to protect this three released areas, develop studies in fidelity sites and one new release area in Ceara coast.
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Luna, Fábia de Oliveira; Beaver, Caitlin E.; Nourisson, Coralie; Bonde, Robert K.; Attademo, Fernanda L. N.; Miranda, Adriana Vieira; Torres-Florez, Juan Pablo; Sousa, Glaucia Pereira de; Passavante, José Zanon; Hunter, Margaret E.
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2021 |
Genetic connectivity of the West Indian Manatee in the southern range and limited evidence of hybridization with Amazonian manatees.
Front. Mar. Sci. 7: 574455. 4 tabs. 4 figs. + online supplementary material. https://doi.org/10.3389/fmars.2020.574455 Jan. 6, 2021.
–ABSTRACT: The Antillean subspecies of the West Indian manatee is classified as endangered by the International Union for the Conservation of Nature (IUCN) Red List. In Brazil, the manatee population is listed as endangered with an estimated population size of 500–1,000. Historic hunting, recent habitat degradation, and fisheries bycatch have decreased the population size. The Amazonian manatee is listed as vulnerable by the IUCN with unknown population sizes within Brazil. The Antillean manatee occurs in sympatry with the Amazonian manatee in Brazil and hybridization has been previously indicated. To provide information on the genetic structure, diversity, and degree of hybridization in the sympatric zone near the Amazon River mouth, the mitochondrial DNA control region and 13 nuclear microsatellite markers were assessed on the two species. Samples were analyzed from the Antillean subspecies across its distribution in Brazil (n = 78) and from the Amazonian species (n = 17) at the Amazon River mouth and inland mainstem river. To assess the previously defined evolutionary significant units of Antillean manatees in the area, an additional 11 samples from Venezuela and Guyana were included. The Antillean manatee was found to be a single population in Brazil and had lower than average number of alleles (3.00), expected heterozygosity (0.34), and haplotype diversity (0.15) when compared to many other manatee populations. The low values may be influenced by the small population size and extended pressures from anthropogenic threats. Gene flow was identified with Venezuela/Guyana in admixed Antillean Brazil samples, although the two populations were found to be moderately divergent. The nuclear loci in Venezuela/Guyana Antillean manatee samples indicated high differentiation from the samples collected in the Amazon River (FST = 0.35 and RST = 0.18, p = 0.0001). No indication of nuclear hybridization was found except for a single sample, "Poque" that had been identified previously. The distribution of Antillean manatees in Brazil is extensive and the areas with unique habitat and threats would benefit from independent management and conservation actions. Gene flow, resulting in genetic diversity and long-term population stability, could be improved in the southern range through habitat restoration, and the establishments of travel corridors and protected areas, which are particularly important for successful parturition and neonatal calf survival.
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Bibliography and Index of the Sirenia and Desmostylia 