Morphology of the Guiana dolphin (Sotalia guianensis) off southeastern Brazil: growth and geographic variation

Ramos, Renato Moran; Beneditto, Ana Paula Madeira Di; Siciliano, Salvatore; Santos, M. C.; Zerbini, Alexandre N.; Vicente, A. F. C.; Zampirolli, E.; Alvarenga, Fernando Siqueira; Fragoso, Ana Bernadete Lima; Lailson‐Brito, José; Azevedo, Alexandre F.; Barbosa, Lupércio de Araújo; Lima, Neuza Rejane Wille

doi:10.5597/lajam00163

Cited by 11 publications

(21 citation statements)

References 17 publications

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“…However, the authors noticed that growth of males may be discontinuous at the age of 5 years, with a secondary growth process at puberty, which required that separate growth curves for sexes. The Gompertz model is often employed in small cetacean morphology studies (Fernandez and Hohn, 1998;Ramos et al, 2000Ramos et al, , 2010Di Beneditto and Ramos, 2004). Di Beneditto and Ramos (2004) used the Gompertz model to conclude that maximum TL was 191 cm for S. guianensis in northern Rio de Janeiro, a value that is higher than that observed in the other study sites mentioned.…”

Section: Discussionmentioning

confidence: 74%

“…However, in the present study the asymptotic TL value was near the mean value, when compared with the other regions surveyed. (Ramos et al, 2010). As observed by Ramos et al (2010), length obeys a clinal gradient that increases with latitude and, under specific conditions, factors other than heat conservation may affect geographic variation, such as nutrition requirements.…”

Section: Discussionmentioning

confidence: 90%

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Variation of age and total length in Sotalia guianensis (Van Bénéden, 1864) (Cetacea, Delphinidae), on the coast of Espírito Santo state, Brazil

et al. 2016

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Variations of age and total length of Sotalia guianensis from the state of Espírito Santo, Brazil, were evaluated. Specimens were found stranded. Age and total length of 44 Guiana dolphins were assessed based on tooth analysis. Age varied between 0.5 year and 33 years (mean = 8.23 years). Most specimens were between zero and 6 years old (47%). Total length varied from 119 cm to 198 cm, with mean of 172.52 cm. Asymptotic length was reached at 185 cm and approximately 5-6 years of age. Mean total length and age were higher than in other regions of the distribution range of the species. Nevertheless, more studies have to be carried out to evaluate the morphological variations in S. guianensis populations in the study area and Brazil.Keywords: Guiana dolphin, age, total length. Variação etária e de comprimento total de

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 90%

Variation of age and total length in Sotalia guianensis (Van Bénéden, 1864) (Cetacea, Delphinidae), on the coast of Espírito Santo state, Brazil

et al. 2016

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“…Other ecological parameters have been used to differentiate ecological stocks. Different geographic areas (Espírito Santo, north and south Rio de Janeiro and São Paulo) have been recognized mainly for cranial and feeding apparatuses variables 97 . Cranial morphometry exhibited a latitudinal growth pattern from North to South, i.e., specimens from São Paulo had smaller skulls.…”

Section: Discussionmentioning

confidence: 99%

Resource partitioning among stranded aquatic mammals from Amazon and Northeastern coast of Brazil revealed through Carbon and Nitrogen Stable Isotopes

Costa

Botta

Siciliano

et al. 2020

Sci Rep

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Aquatic mammals play an important role in community structure. The present study applied stable isotope analysis (SIA) to evidence trophic relationships and resource partitioning among aquatic mammals inhabiting different environments in the Amazon estuarine complex and adjacent coastal zone (AE) and Northeastern coast (NC) of Brazil. In addition, isotopic niche partitioning among Sotalia guianensis , Inia spp. and Trichechus inunguis within the AE was also evaluated, and ecological S. guianensis stocks were characterized. Among marine delphinids, the carbon isotopic composition in offshore species mirrored that of nearshore species, contradicting the pattern of decreasing δ 13 C values characteristic of many areas around the world including areas in Southeastern and Southern Brazil. Isotopic niches were highly distinct, with no overlap among the assessed species inhabiting the AE. Inia spp. and T. inunguis occupied significantly larger isotopic niche spaces, suggesting high habitat plasticity. S. guianensis inhabited two coastal regions indicating an ecological distinction. Nitrogen values were similar between S. guianensis from the NC and AE, indicating comparable trophic positions. However, NC specimens presented more variable δ 13 C values compared to those from AE. SIA results also allowed for insights concerning habitat use and the trophic ecology of dolphin species inhabiting different oceanographic regions off Northern/Northeast Brazil. These findings provide novel data on the stable isotope composition for cetaceans and sirenians from this region, and aid in furthering knowledge on the trophic ecology and habitat use of the investigated species.

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“…The Gompertz model is conventionally used in studies of the morphology of dolphins (Fernandez and Hohn 1998;Ramos et al 2000aRamos et al , 2010Ramos et al , 2002Di Beneditto and Ramos 2004). However, in the study by Ramos et al (2010), it did not show good fit with the variables TBL and age of Guiana dolphins in Espírito Santo, Brazil, when the asymptote was reached at the age of 10.…”

Section: Discussionmentioning

confidence: 99%

“…These parameters reveal a great deal of information about adaptation to the environment, and analysis can indicate how flippers evolved (Felts 1966). Studies on physical maturity mainly focus on TBL and when other morphometric variables correlated with age are used, the focus is on the differentiation of populations, as in the study by Ramos et al (2010) and Lima (2012). Additionally, studies that consider stages of epiphyses ossification in the thoracic limb, such as in Guiana dolphins, use age and TBL to assess bone maturity (Ogden et al 1981;Calzada and Aguilar 1996;Di Giancamillo et al 1998;Carvalho 2011).…”

Section: Discussionmentioning

confidence: 99%

Thoracic limb bone development inSotalia guianensis(Van Beneden 1864) along the coastline of Espírito Santo, Brazil

Azevedo¹,

Lima²,

Azevedo³

et al. 2015

JMAMMAL

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The skeleton is often the only remaining structure of the Guiana dolphin, Sotalia guianensis, after decomposition of carcasses. This study investigates the bone development of Guiana dolphins beached on the coastline of the state of Espírito Santo, Brazil. External measurements of 43 thoracic limbs were obtained. Internal structures (radius, ulna, and humerus) were also measured. Dual-energy X-ray absorptiometry (DXA) was used to evaluate bone mass. The variables concerning the thoracic limb were tested using the Akaike information criterion to scale the best growth model when correlated with age and by the allometric model when they were correlated with total body length. The efficacy of DXA was also tested. The Brody growth model (best fit) showed that the thoracic limb stopped growing around the age of 2, while total body length ceased to grow at the age of 5.5. The thoracic limb presented early growth (negative allometry) compared with total body length. The methodology used to measure bone mass was efficient when considering ash weight. No difference in bone density was observed between the right and the left forelimb (P > 0.05), male and female (P > 0.05), or between dolphins found in the 3 sites we monitored. The deposition of bone mass was high in the early stages of life, and stabilization occurred at around the age of 13. O esqueleto muitas vezes é a estrutura que resta da espécie Sotalia guianensis, boto-cinza, devido ao processo de decomposição em que as carcaças são encontradas. O objetivo do presente estudo é entender o desenvolvimento ósseo dos animais encontrados encalhados no litoral do Espírito Santo. Para isso, 43 pares de nadadeiras peitorais foram submetidos às mensurações externas e de estruturas ósseas internas (rádio, ulna e úmero) e à técnica de absorciometria de raio-x de dupla energia (DEXA) para massa óssea. As variáveis das nadadeiras foram testadas pelo critério de Akaike para escalonamento do melhor modelo de crescimento quando correlacionadas com a idade, e para o modelo alométrico quando correlacionadas com o comprimento total (CT). Foi testada a eficácia da DEXA. através do modelo de crescimento de Brody (melhor ajuste) e pode-se observar que as nadadeiras param de crescer por volta dos 2 anos de idade e o comprimento total do corpo aos 5.5 anos, apresentando essas estruturas crescimento precoce (alometria negativa) em relação ao CT. A metodologia aplicada para mensuração da massa óssea mostrou-se eficaz quando correlacionada com peso das cinzas. Não houve diferença de densidade óssea entre nadadeira direita e esquerda (P > 0.05), macho e fêmea (P > 0.05) e nem entre os animais dos três diferentes locais de ocorrência, pois todos estavam dentro do mesmo intervalo de confiança. A deposição da massa óssea é acentuada no início da vida com posterior estabilização por volta dos13 anos de idade.

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Morphology of the Guiana dolphin (Sotalia guianensis) off southeastern Brazil: growth and geographic variation

Cited by 11 publications

References 17 publications

Variation of age and total length in Sotalia guianensis (Van Bénéden, 1864) (Cetacea, Delphinidae), on the coast of Espírito Santo state, Brazil

Variation of age and total length in Sotalia guianensis (Van Bénéden, 1864) (Cetacea, Delphinidae), on the coast of Espírito Santo state, Brazil

Resource partitioning among stranded aquatic mammals from Amazon and Northeastern coast of Brazil revealed through Carbon and Nitrogen Stable Isotopes

Thoracic limb bone development inSotalia guianensis(Van Beneden 1864) along the coastline of Espírito Santo, Brazil

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