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Navegando por Assunto "Reproduction"

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    Green turtle (Chelonia mydas) nesting on Atol das Rocas, north-eastern Brazil, 1990–2008
    (2012-04-25) Bellini, C.; Santos, A.J.B; Grossman, A.; Barata, P.C.R.; Marcovaldi, M.A.
    In this paper, information is presented on green turtle (Chelonia mydas) nesting on Atol das Rocas (Rocas Atoll), north eastern Brazil. The temporal distribution of nesting events per season, annual number of nests, carapace length of nesting females, clutch size, hatching success, incubation period, internesting interval, clutch frequency, observed reproductive life span, and remigration period are reported. The study period included the nesting seasons from 1990 to 2008, but no regular beach monitoring was carried out in 1998 and 1999. Two sorts of methods were applied to the estimation of the annual number of nests in some seasons. Taking into account the estimated annual numbers of nests, the mean annual number of nests in the study period, excluding 1998–1999, was 335 (standard deviation ¼ 139, range ¼ 136–563, N ¼ 17). An analysis of the available data indicates that the average nesting levels at the beginning of the study period (the first five seasons) and at its end (the last five seasons) were roughly the same. The mean curved carapace length of the nesting turtles decreased significantly during the study period, from 115.9 cm in 1990–1992 to 112.9 cm in 2006 –2008. Atol das Rocas was established as a federal biological reserve in 1979, but regular sea turtle conservation activities actually started there in 1990. Since that year, the killing of nesting turtles has ceased, nesting activity by the turtles can proceed in an undisturbed fashion, and their clutches can incubate in a protected environment.
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    Nesting Biology and conservation of the leatherback sea turtle (Dermochelys coriacea) in Espírito Santo State, Brazil, 1988-1989 to 2003-2004.
    (Chelonian Conservation and Biology, 2007-05-01) THOMÉ, J. C. A; BAPTISTOTTE, C; MOREIRA, L. M. P; SCALFONI, J. T; ALMEIDA, A. P; RIETH, D. B; BARATA, P. C. R
    In Brazil, the only area where regular leatherback sea turtle (Dermochelys coriacea) nesting is known to occur is located on the northern coast of the state of Espı´rito Santo, around latitude 198S. In this study, we present the field methods used by Projeto TAMAR-IBAMA (the Brazilian Sea Turtle Conservation Program) in the state of Espı´rito Santo and analyze data on leatherback nesting from 1988–1989 to 2003–2004. In that period, 527 nests were observed in the study area. The annual number of nests varied between 6 (in 1993–1994) and 92 (in 2002–2003). Between 1995–1996 and 2003–2004, the annual number of nests increased at about 20.4% per year on average. Among the 527 clutches observed, 358 (67.9%) were left in situ, 50 (9.5%) were relocated to another spot on the beach, 88 (16.7%) were relocated to open-air beach hatcheries, and 31 clutches (5.9%) did not have their management decision recorded. Curved carapace length of nesting females was in the range of 139–182 cm (mean ¼ 159.8 cm). At present, there is no significant alteration of the nesting habitat in Espı´rito Santo, egg poaching has been reduced to very low levels, and there is no subsistence hunting for sea turtles of any species. The main challenges to leatherback conservation currently are the incidental capture in artisanal fisheries operating close to nesting beaches and in high seas fisheries operating in the South Atlantic, as well as activities related to the oil industry. An overview of Projeto TAMAR’s actions addressing current sea turtle conservation issues in the State of Espı´rito Santo is presented.
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    Reproductive biology and conservation status of the loggerhead sea turtle (Caretta caretta) in Espirito Santo State, Brazil.
    (2000) BAPTISTOTTE, C; THOMÉ, J. C. A; BJORNDAL, K
    The reproductive biology of loggerheads nesting in Espírito Santo, Brazil, is evaluated for six nesting seasons (1991/1992 through 1996/1997), through data gathered by Projeto TAMAR-IBAMA, the Brazilian sea turtle conservation program. Mean curved carapace length of nesting females was 102.7 cm (n=198). Mean clutch size for clutches with more than 50 eggs was 119.7 (n=3664), and clutch size was significantly correlated with female body size. Management practices had significant effects on hatching success and incubation time. Mean hatching success of nests left in situ was 68.3% (n=879), of undepredated nests left in situ was 79.9% (n=751), and of nests moved to hatcheries and not depredated was 67.7% (n=2786). For nests moved to hatcheries, hatching success declined significantly with increasing time interval between oviposition and transfer to the hatchery. Mean incubation time was 59.5 days for nests left in situ (n=572) and 57.2 days for nests moved to hatcheries (n=2179). Incubation time declined significantly throughout the nesting season as temperatures increased; we conclude that sex ratio of hatchlings also shifts to more females as the season progresses. There was significant annual variation for all parameters. A short review of the conservation status of loggerheads in Espírito Santo State is also presented.
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    Reproductive success of Antillean manatees released in Brazil: implications for conservation
    (2022-07-26) Attademo, Fernanda Loffler Niemeyer; Normande, Iran Campello; Sousa, Glaucia Pereira; Costa, Alexandra Fernandes; Borges, João Carlos Gomes; Alencar, Ana Emília Barbosa de; Foppel, Ernesto Frederico da Costa; Luna, Fábia de Oliveira
    Actions to rescue, rehabilitate and release calves of manatees are the main initiatives and strategies for conservation of the species in Brazil. The survival rate of animals in a natural environment and the reproductive success, identified by birth records, are some of the indicators used to estimate the release success for manatees. This study evaluated the effectiveness of releases of West Indian manatees based on the reproductive success of rescued animals that were released back into the wild in Brazil. Twenty-two female manatees were released in the states of Alagoas (into an extinct area) and Paraíba (into an existent population) from 1994–2020. Six females gave birth to 13 calves, all in Alagoas State. The average age of the first calving event was 11.7 (±1.49) years and 8.0 (±1.41) years after release. Among the females that had more than one calving, the average was 3.6 (±1.18) years between each calving. All calves observed were born alive; nevertheless, three (23.1%) died a few weeks after birth. In general, females rehabilitated in captivity and released in the wild were able to reproduce, especially in protected areas. This study emphasizes the need to intensify actions for the conservation of manatees and their habitats in order to achieve healthier wild populations.

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