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Paulo C Simoeslopes - One of the best experts on this subject based on the ideXlab platform.
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prey consumed by guiana dolphin Sotalia guianensis cetacea delphinidae and franciscana dolphin pontoporia blainvillei cetacea pontoporiidae in an estuarine environment in southern brazil
Iheringia Serie Zoologia, 2012Co-Authors: Marta J Cremer, Pedro C Pinheiro, Paulo C SimoeslopesAbstract:The present study provides information about the diet of sympatric populations of small cetaceans in the Babitonga Bay estuary. This is the first study on the diet of these species in direct sympatry. The stomach contents of seven Guiana dolphins Sotalia guianensis and eight franciscanas Pontoporia blainvillei were analyzed. The prey of both cetaceans was mostly teleost fishes, followed by cephalopods. We identified 13 teleost fishes as part of the diet of the franciscanas, and 20 as part of the diet of Guiana dolphins. Lolliguncula brevis was the only cephalopod recorded, and was the most important prey for both cetaceans. Stellifer rastrifer and Gobionellus oceanicus were also important for franciscana, so as Mugil curema and Micropogonias furnieri were important for Guiana dolphins. Stellifer rastrifer and Cetengraulis edentulus were the fishes with the highest frequency of occurrence for franciscana (50%), while Achirus lineatus, C. edentulus, S. brasiliensis, Cynoscion leiarchus, M. furnieri, M. curema, Diapterus rhombeus, Eugerres brasilianus and G. oceanicus showed 28.6% of frequency of occurrence for Guiana dolphins. Franciscanas captured greater cephalopods than the Guiana dolphins in both total length (z= -3.38; n= 40; p< 0.05) and biomass (z = -2.46; n = 40; p<0.05). All of the prey species identified occur inside the estuary, which represents a safe habitat against predators and food availability, reinforcing the importance of the Babitonga Bay for these cetacean populations.
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assessing population parameters and trends of guiana dolphins Sotalia guianensis an eight year mark recapture study
Marine Mammal Science, 2012Co-Authors: Mauricio Cantor, Marcos R Rossisantos, Leonardo L. Wedekin, Fabio G Daurajorge, Paulo C SimoeslopesAbstract:This study represents the first attempt to study the population dynamics of Guiana dolphins (Sotalia guianensis), by evaluating a set of demographic parameters. The population of the Caravelas River estuary, eastern Brazil, was systematically monitored through a long-term mark-recapture experiment (2002–2009). Abundance estimates revealed a small population (57–124 dolphins), comprised of resident dolphins and individuals that temporarily leave or pass through the study area. Temporary emigration from the estuary to adjacencies (γ″= 0.33 ± 0.07 SE) and return rate (1 −γ′= 0 .67) were moderate and constant, indicating that some dolphins use larger areas. Survival rate (ϕ= 0.88 ± 0.07 SE) and abundance were constant throughout the study period. Power analysis showed that the current monitoring effort has high probability of detecting abrupt population declines (1 −β= 0.9). Although the monitoring is not yet sensitive to subtle population trends, sufficient time to identify them is feasible (additional 3 yr). Despite such apparent stability, this population, as many others, inhabits waters exposed to multiple human-related threats. Open and closed population modeling applied to photo-identification data provide a robust baseline for estimating several demographic parameters and can be applied to other populations to allow further comparisons. Such synergistic efforts will allow a reliable definition of conservation status of this species.
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habitat preferences of guiana dolphins Sotalia guianensis cetacea delphinidae in norte bay southern brazil
Journal of the Marine Biological Association of the United Kingdom, 2010Co-Authors: Leonardo L. Wedekin, Fabio G Daurajorge, Paulo C SimoeslopesAbstract:Habitat preference and spatial distribution of Guiana dolphins (Sotalia guianensis) in Norte Bay, southern Brazil, was studied from 2001 to 2005. Boat surveys (N=91) were made to evaluate the spatial distribution of the dolphins. Seven habitat variables were integrated into a geographical information system, and habitat preference was tested using the 'Neu method' and a habitat index. The Guiana dolphins did not use all habitat types in the same proportion as were available. Areas used more intensively included, in order of importance: (1) areas with a steep sloping sea-floor; (2) areas further from urban areas; ( 3 ) areas further from mangroves; ( 4 ) areas near the mouth of the bay; ( 5 ) shallow water areas; (6) areas of clayey-silt sediments; and ( 7 ) areas close to shore. From 2001 to 2005 there was a shift in spatial distribution and habitat use by the dolphins. The low frequency of use of areas close to urban encroachment and its related impacts to the marine environment raises concern about the coastal habitat destruction. The Guiana dolphin may be considered a habitat specialist, despite its wide latitudinal distribution in the western Atlantic Ocean. The ecological niche of the species may be defined by a narrow strip of shallow coastal waters (mostly < 30 m) bordering the coastline. The shift in the spatial use was probably linked with changes in the abundance of important prey of the species and possibly was caused by the collapse of a fish stock in the study area region. Different habitats may favour different assemblages of prey and consequently different foraging strategies by the dolphins. Human-related habitat alterations throughout the range of this species are likely to affect dolphins' ecology in many ways and, thus, must be evaluated and mitigated to conserve their critical habitats.
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padroes comportamentais e intensidade de movimentos de Sotalia guianensis p j van beneden cetacea delphinidae em duas diferentes areas da costa brasileira
Revista Brasileira De Zoologia, 2007Co-Authors: Fabio G Daurajorge, Marcos R Rossisantos, Leonardo L. Wedekin, Paulo C SimoeslopesAbstract:The behavioral patterns of the estuarine dolphin, Sotalia guianensis (P. J. van Beneden, 1864), were compared between two populations along the Brazilian coast: Caravelas (Bahia), along the eastern coast, and Norte Bay (Santa Catarina), along the southern coast. Applying the focal-group sampling in both areas, information such as the geographic position (UTM) of groups and predominant behavioral patterns were obtained. Geographic positions were used to calculate the total distance traveled by estuarine dolphin groups on each observation day. Since the distance traveled varies with time, the daily mean speed of the dolphin’s group was used as an index of movement intensity. Two comparable and easily recognizable behavioral patterns were considered: travelling and foraging. Overall movement intensity and behavioral pattern frequency were similar between both areas. However, a seasonal variation was observed in both parameters in Norte Bay, while in Caravelas these parameters were homogeneous throughout the year. Variation in the behavior of the estuarine dolphin was consistent with variations in environmental factors, such as water temperature.
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seasonal variations in spatial usage by the estuarine dolphin Sotalia guianensis van beneden 1864 cetacea delphinidae at its southern limit of distribution
Brazilian Journal of Biology, 2007Co-Authors: Leonardo L. Wedekin, Fabio G Daurajorge, Vitor De Q Piacentini, Paulo C SimoeslopesAbstract:The use of space by the resident population of estuarine dolphins (Sotalia guianensis) in Norte Bay, southern Brazil was studied by boat surveys between 2000 and 2003. Data such as the geographical position and group size was collected at 5-minute intervals using focal-group sampling. The distribution and seasonal and daily group home-ranges were estimated using a GIS (Geographic Information System) environment. The dolphins did not use the area homogeneously, restricting their activities to a well-defined area located in the western part of the bay, while the use of the eastern part was not observed. A discrepancy between the Environment Protection Area of Anhatomirim, created especially to protect this population and the distribution of the dolphins was observed. Seasonal group home-range varied both qualitatively and quantitatively among the four consecutive seasons analyzed. The dolphins tended to use a larger area in cold seasons, when apparently the abundance of major prey items is lower. Core areas of intense use were identified, and also varied seasonally. These core areas may be regarded as critical habitats and require special legislation and control. The mean daily group home-range did not differ statistically among seasons. The present study corroborates a spatially strict residency pattern of the estuarine dolphin in highly productive coastal ecosystems.
Jose Lailsonbrito - One of the best experts on this subject based on the ideXlab platform.
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the first confirmed decline of a delphinid population from brazilian waters 2000 2015 abundance of Sotalia guianensis in guanabara bay south eastern brazil
Ecological Indicators, 2017Co-Authors: Alexandre F Azevedo, Tatiana L Bisi, Haydée A. Cunha, Rafael R Carvalho, Maja Kajin, M Van Sluys, Jose LailsonbritoAbstract:Abstract The abundance of Guiana dolphins ( Sotalia guianensis ) in Guanabara Bay, Rio de Janeiro, South-eastern Brazil, was investigated during the period 2000–2015 using mark-recapture models applied to photo-identification data. A combination of Pradel’s model and Pollock’s robust design was applied to estimate abundance and other population parameters, such as apparent survival (Φ), capture probability (p) and seniority probability (γ). Total population size was estimated by correcting the estimates derived from the Pradel robust design model for the proportion of marked individuals in the population. The corrected abundance estimates decreased drastically (37%) between 2000 (62, 95% CI 59–65) and 2015 (39, 95% CI 37–40), and can be explained by a combination of low survival and recruitment rates. Determining the ultimate causes for the decline in this Guiana dolphin population is difficult, but the likely reasons are of anthropogenic nature, such as by-catch, habitat degradation, intense traffic of vessels and exposure to immunosuppressive and endocrine-disrupting pollutants. We provide the first quantitative evidence of population decline in a delphinid from Brazilian waters. Conservation and management actions are urged to change this scenario. Other local dolphin populations in Brazil, which are exposed to the same impacts, may also be currently declining or are expected to do so in the near future. For this reason, we emphasize that anthropogenic impacts upon estuarine/coastal species that exhibit site fidelity warrant greater attention, because such impacts may lead to the same negative scenario observed in Guanabara Bay.
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morphology of the guiana dolphin Sotalia guianensis off southeastern brazil growth and geographic variation
Latin American Journal of Aquatic Mammals, 2010Co-Authors: Renata Maria Arruda Ramos, Salvatore Siciliano, Marcos César De Oliveira Santos, Alexandre N. Zerbini, Ana Bernadete Lima Fragoso, A P M Di Beneditto, A F C Vicente, E Zampirolli, Fernando Siqueira Alvarenga, Jose LailsonbritoAbstract:The objective of this study was to analyze the morphology of Guiana dolphin (Sotalia guianensis) to evaluate the existence of geographical variation along southeastern Brazil. Body length and 39 cranial variables were measured of specimens stranded or accidentally captured to consider ontogenetic and geographic variations. The areas studied were Espirito Santo (ES; 18o30'S-20o40'S), northern Rio de Janeiro (NRJ; 21o35'S-22o25'S), southern Rio de Janeiro (SRJ; 23o00'S-23o07'S) and Sao Paulo (SP; 23o30'S-25o30'S). Body length at age zero predicted by a non-linear Gompertz model for the Guiana dolphin was 148.3cm for area ES, 108.97cm for area NRJ, 98.4cm for area SRJ and 90.9cm for area SP. Asymptotic values were reached at about six years of age for total body length and cranial variations. These results indicate that Guiana dolphins reach adult size and sexual maturity simultaneously at six to seven years of age, when specimens cease to grow. The growth pattern for body and skull size indicated that there is variation between geographic areas. Guiana dolphins found in Sao Paulo are smaller than those analyzed in northern Rio de Janeiro and Espirito Santo, which implies a different growth rate. A canonical discriminant analysis of the cranial metric characters indicated significant differences between the four geographic areas. Differences between areas NRJ, SRJ and SP were responsible for 54% (axis 1) and 34% (axis 2) of the variation, respectively. The third axis depicted a difference between the area ES and the others. A partial overlap between geographic areas was observed in the projection of the species on the canonical axes, suggesting parapatry. Geographic variation recorded in this study is likely to be related to environmental adaptations. One of the areas that could play a role in the distribution of Guiana dolphin in the surveyed area is the central coast of Rio de Janeiro, which is characterized by the absence of river discharges, a narrowing of the continental shelf and upwelling influence that might be limiting the species occurrence in this area. RESUMO: O objetivo do presente estudo foi analisar a morfologia do boto-cinza (Sotalia guianensis) para avaliar a existencia de variacao geografica no sudeste do Brasil. O comprimento do corpo e 39 variaveis cranianas foram medidas em animais encalhados ou capturados acidentalmente em rede de pesca para analisar a variacao ontogenica e geografica. As areas estudadas foram Espirito Santo (ES) (18o30'S-20o40'S), norte do Rio de Janeiro (NRJ) (21o35'S-22o25'S), sul do Rio de Janeiro (SRJ) (23o00'S-23o07'S) e Sao Paulo (SP) (23o30'S-25o30'S). O comprimento do corpo na idade zero, predito pela curva de crescimento de Gompertz para o boto-cinza foi 148,3cm para a area ES, 108,97cm para a area NRJ, 98,4cm para a area SRJ e 90,9cm para a area SP. Os valores assintoticos foram alcancados aproximadamente aos seis anos de idade para o comprimento do corpo e variaveis cranianas. Esses resultados indicam que o boto-cinza alcanca o tamanho adulto e a maturidade sexual simultaneamente aos seis a sete anos de idade, quando os especimes param de crescer. Os padroes de crescimento para o tamanho corporeo e craniano indicaram que ha uma variacao entre areas geograficas. Os especimes de botos-cinza encontrados em Sao Paulo sao menores do que aqueles analisados no norte do Rio de Janeiro e Espirito Santo, o que implica em uma taxa de crescimento diferenciada. A analise discriminante canonica para os caracteres metricos do crânio indicou diferenca significativa entre as quatro areas geograficas. Diferencas entre as areas NRJ, SRJ e SP foram responsaveis por 54% (eixo 1) e 34% (eixo 2) da variacao. A diferenca entre a area ES das demais areas foi responsavel pelos 12% restantes (eixo 3). Uma sobreposicao parcial entre as areas geograficas foi observada na projecao das especies nos eixos canonicos, sugerindo parapatria.. A variacao geografica registrada neste estudo pode ser um reflexo de adaptacoes ambientais. Uma area que pode ser considerada critica para a distribuicao do boto-cinza e a costa central do Rio de Janeiro, a qual e caracterizada pela ausencia de rios, plataforma continental estreita e influencia de ressurgencia. Estas caracteristicas ambientais podem ser limitantes para a ocorrencia da especie nesta area.
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high organochlorine accumulation in blubber of guiana dolphin Sotalia guianensis from brazilian coast and its use to establish geographical differences among populations
Environmental Pollution, 2010Co-Authors: Alexandre F Azevedo, Paulo R. Dorneles, Lara G. Vidal, C.p.c. Lozinski, Jose Lailsonbrito, Claudio E Azevedosilva, Regina Zanelatto, Antonio AzeredoAbstract:Blubber samples from 33 Guiana dolphins (Sotalia guianensis) from three estuaries (Guanabara, Sepetiba/Ilha Grande and Paranagua Bays) of Southern and Southeastern Brazil were analyzed for organochlorine compounds (DDTs, PCBs and HCB). The sampled individuals were incidentally captured in gillnet fishery between 1995 and 2005. The concentrations (in ng/g lipids) varied from 652 to 23 555 for ΣDDT; from 765 to 99 175 for ΣPCB; and from <4.4 to 156 for HCB. The results have shown that cetaceans from Brazil present organochlorine concentrations that are comparable to those reported for highly industrialized regions of Northern Hemisphere. Using discriminant analysis it was possible to verify that the dolphin populations from the three bays present different organochlorine accumulation patterns. This feature allows the use of this set of pollutants as an auxiliary tool for identification of different populations of the species off Brazilian Coast.
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human induced injuries to marine tucuxis Sotalia guianensis cetacea delphinidae in brazil
Marine Biodiversity Records, 2009Co-Authors: Alexandre F Azevedo, Haydée A. Cunha, Paulo R. Dorneles, Jose Lailsonbrito, Monique Van Sluys, Ana Bernadete Lima FragosoAbstract:Guanabara Bay constitutes the most degraded habitat along the marine tucuxi dolphin (Sotalia guianensis) distribution. Considering that these mammals are found year-round in this area, where the dolphin population is estimated to be approximately 70 individuals, interactions between cetaceans and human activities are of concern. From 1995 to 2005, photo-identification techniques have been employed to study marine tucuxis in Guanabara Bay and data on the individual injuries has been collected. Seven out of 78 photo-identified and catalogued individuals presented noticeable injuries on their bodies, including cut-like wounds, skin ulceration and mutilation. Parts of fishing gear attached to the bodies of some dolphins were also observed. The concern elicited by the injuries reported here is amplified if we consider that this cetacean population is highly exposed to contaminants of known immunosuppressive action, such as organochlorine, organotin and perfluoroalkyl compounds.
Alexandre F Azevedo - One of the best experts on this subject based on the ideXlab platform.
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High-frequency social communication in Sotalia guianensis
The Journal of the Acoustical Society of America, 2019Co-Authors: Mariana Barbosa, Tatiana L Bisi, José Lailson-brito, Lis Bittencourt, Luciana Guimarães De Andrade, Alexandre F AzevedoAbstract:This study aimed to investigate the use of high ultrasonic frequencies (above 40 kHz) in the Sotalia guianensis whistle repertoire. The whistles were classified as high-frequency (HF) whistles and very high-frequency (VHF) whistles. Seven parameters were extracted and a general linear mixed effects model was performed between the total number of whistles and VHF ones. Frequency parameters of HF and VHF whistles were the highest reported for this species so far. However, VHF whistles were rare and occurred in situations of high acoustic activity, which may represent a strategy used by dolphins to deal with higher levels of vocalization rates.
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the first confirmed decline of a delphinid population from brazilian waters 2000 2015 abundance of Sotalia guianensis in guanabara bay south eastern brazil
Ecological Indicators, 2017Co-Authors: Alexandre F Azevedo, Tatiana L Bisi, Haydée A. Cunha, Rafael R Carvalho, Maja Kajin, M Van Sluys, Jose LailsonbritoAbstract:Abstract The abundance of Guiana dolphins ( Sotalia guianensis ) in Guanabara Bay, Rio de Janeiro, South-eastern Brazil, was investigated during the period 2000–2015 using mark-recapture models applied to photo-identification data. A combination of Pradel’s model and Pollock’s robust design was applied to estimate abundance and other population parameters, such as apparent survival (Φ), capture probability (p) and seniority probability (γ). Total population size was estimated by correcting the estimates derived from the Pradel robust design model for the proportion of marked individuals in the population. The corrected abundance estimates decreased drastically (37%) between 2000 (62, 95% CI 59–65) and 2015 (39, 95% CI 37–40), and can be explained by a combination of low survival and recruitment rates. Determining the ultimate causes for the decline in this Guiana dolphin population is difficult, but the likely reasons are of anthropogenic nature, such as by-catch, habitat degradation, intense traffic of vessels and exposure to immunosuppressive and endocrine-disrupting pollutants. We provide the first quantitative evidence of population decline in a delphinid from Brazilian waters. Conservation and management actions are urged to change this scenario. Other local dolphin populations in Brazil, which are exposed to the same impacts, may also be currently declining or are expected to do so in the near future. For this reason, we emphasize that anthropogenic impacts upon estuarine/coastal species that exhibit site fidelity warrant greater attention, because such impacts may lead to the same negative scenario observed in Guanabara Bay.
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High-frequency whistles of Guiana dolphins (Sotalia guianensis) in Guanabara Bay, southeastern Brazil.
The Journal of the Acoustical Society of America, 2015Co-Authors: Luciana Guimarães De Andrade, Tatiana L Bisi, Lis Bittencourt, Isabela Maria Seabra De Lima, José Lailson Brito Júnior, Alexandre F AzevedoAbstract:Guiana dolphins produce whistles with a higher frequency and less complexity than most other delphinid species. The present study used a recording system with sampling rate of 192 kHz to describe the high-frequency whistles of Sotalia guianensis in Guanabara Bay, Rio de Janeiro. Eleven acoustic parameters (start, end, minimum, maximum, delta, center and peak frequency, duration, and frequency at 14, 12, and 34 of duration) were measured for all whistles. Whistles with a fundamental frequency up to 66.7 kHz were reported, thereby expanding the known frequency range of this species.
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high organochlorine accumulation in blubber of guiana dolphin Sotalia guianensis from brazilian coast and its use to establish geographical differences among populations
Environmental Pollution, 2010Co-Authors: Alexandre F Azevedo, Paulo R. Dorneles, Lara G. Vidal, C.p.c. Lozinski, Jose Lailsonbrito, Claudio E Azevedosilva, Regina Zanelatto, Antonio AzeredoAbstract:Blubber samples from 33 Guiana dolphins (Sotalia guianensis) from three estuaries (Guanabara, Sepetiba/Ilha Grande and Paranagua Bays) of Southern and Southeastern Brazil were analyzed for organochlorine compounds (DDTs, PCBs and HCB). The sampled individuals were incidentally captured in gillnet fishery between 1995 and 2005. The concentrations (in ng/g lipids) varied from 652 to 23 555 for ΣDDT; from 765 to 99 175 for ΣPCB; and from <4.4 to 156 for HCB. The results have shown that cetaceans from Brazil present organochlorine concentrations that are comparable to those reported for highly industrialized regions of Northern Hemisphere. Using discriminant analysis it was possible to verify that the dolphin populations from the three bays present different organochlorine accumulation patterns. This feature allows the use of this set of pollutants as an auxiliary tool for identification of different populations of the species off Brazilian Coast.
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human induced injuries to marine tucuxis Sotalia guianensis cetacea delphinidae in brazil
Marine Biodiversity Records, 2009Co-Authors: Alexandre F Azevedo, Haydée A. Cunha, Paulo R. Dorneles, Jose Lailsonbrito, Monique Van Sluys, Ana Bernadete Lima FragosoAbstract:Guanabara Bay constitutes the most degraded habitat along the marine tucuxi dolphin (Sotalia guianensis) distribution. Considering that these mammals are found year-round in this area, where the dolphin population is estimated to be approximately 70 individuals, interactions between cetaceans and human activities are of concern. From 1995 to 2005, photo-identification techniques have been employed to study marine tucuxis in Guanabara Bay and data on the individual injuries has been collected. Seven out of 78 photo-identified and catalogued individuals presented noticeable injuries on their bodies, including cut-like wounds, skin ulceration and mutilation. Parts of fishing gear attached to the bodies of some dolphins were also observed. The concern elicited by the injuries reported here is amplified if we consider that this cetacean population is highly exposed to contaminants of known immunosuppressive action, such as organochlorine, organotin and perfluoroalkyl compounds.
Leonardo L. Wedekin - One of the best experts on this subject based on the ideXlab platform.
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Anthropogenic Noise and Guiana Dolphins ( Sotalia guianensis ) in Brazil: Ecological and Conservation Concerns
Advances in Marine Vertebrate Research in Latin America, 2017Co-Authors: Fábio De Sousa Pais, Marcos R. Rossi-santos, Leonardo L. Wedekin, Emygdio L A Monteiro-filho, Rafaela Prado Cardoso, Flávio José De Lima Silva, Dalila Teles Martins LeãoAbstract:The Sotalia guianensis dolphin occurs in the western Atlantic Ocean, from the south of Brazil to Central America. It is a coastal species, much susceptible to human impacts, as anthropogenic noises, which in general causes potential impacts in marine mammals’ populations, because the emission and reception of sound signals plays a complex and vital role in this populations’ ecology through many different ways. This study reviews the acoustic repertoire and potential anthropic impacts on populations of Guiana dolphin (S. guianensis) through its occurrence, and described and compared the anthropogenic noises with the acoustic repertoire of three Brazilian populations: Cananeia estuary – Sao Paulo State, Caravelas estuary – Bahia State and Pipa beach – Rio Grande do Norte State. Data was collected similarly in these three sites during boats surveys using hydrophones and audio recorders. Results showed overlapping of the S. guianensis repertoire and noises produced from boats, dredge activities and wood-barges, leading to harm on individuals and populations. This review has gathered important information supporting marine activity management, and can be used to evaluate acoustic impacts over cetaceans population.
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HABITAT USE OF THE GUIANA DOLPHIN, Sotalia guianensis (CETACEA,
2016Co-Authors: Marcos R. Rossi-santos, Leonardo L. Wedekin, Emygdio Monteiro L. A. FilhoAbstract:ABSTRACT: Habitat use patterns of the Guiana dolphin (Sotalia guianensis) were assessed in the Caravelas River Estuary, eastern Brazilian coast (17°54’S, 39°21’W). During 191 surveys (2002-2004), 187 groups were sighted. The Arcview 3.1 software was used to create a GIS environment that included the distribution of dolphin sightings, a 5x5km quadrats grid, and the bathymetry of the study area. Each quadrat was characterized according to environmental variables such as depth, contour index, distance from sand banks and distance from the coastline. The Caravelas River mouth was found as the core area of the dolphins. Guiana dolphins did not use the several classes of environmental variables homogeneously, occurring more frequently in shallow waters, closer to sand banks and closer to the coastline. Also more dolphins occurred in areas with flatter bottoms and in waters with salinity ranging from 35 to 38ppm, despite dolphins being sighted in waters 14km inside the river. Dolphins used a wide range of habitat types but the Caravelas River mouth seems to propitiate the most adequate conditions for foraging strategies or concentration of prey. RESUMEN: El uso de habitat por el delfin de Guyana (Sotalia guianensis) fue evaluado en el Estuário do Rio Caravelas, costa brasileña (17°54’S, 39°21’W). Durante 191 salidas de campo (2002-2004), 241 grupos fueron avistados. El programa Arcview 3.1 fue utilizado para crear un ambiente SIG el cual incluyó la distribución de las observaciones de delfines, una red de cuadrantes de 5x5km y un modelo batimétrico del área de estudio. Cada cuadrante fue caracterizado de acuerdo con variables ambientales como profundidad
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assessing population parameters and trends of guiana dolphins Sotalia guianensis an eight year mark recapture study
Marine Mammal Science, 2012Co-Authors: Mauricio Cantor, Marcos R Rossisantos, Leonardo L. Wedekin, Fabio G Daurajorge, Paulo C SimoeslopesAbstract:This study represents the first attempt to study the population dynamics of Guiana dolphins (Sotalia guianensis), by evaluating a set of demographic parameters. The population of the Caravelas River estuary, eastern Brazil, was systematically monitored through a long-term mark-recapture experiment (2002–2009). Abundance estimates revealed a small population (57–124 dolphins), comprised of resident dolphins and individuals that temporarily leave or pass through the study area. Temporary emigration from the estuary to adjacencies (γ″= 0.33 ± 0.07 SE) and return rate (1 −γ′= 0 .67) were moderate and constant, indicating that some dolphins use larger areas. Survival rate (ϕ= 0.88 ± 0.07 SE) and abundance were constant throughout the study period. Power analysis showed that the current monitoring effort has high probability of detecting abrupt population declines (1 −β= 0.9). Although the monitoring is not yet sensitive to subtle population trends, sufficient time to identify them is feasible (additional 3 yr). Despite such apparent stability, this population, as many others, inhabits waters exposed to multiple human-related threats. Open and closed population modeling applied to photo-identification data provide a robust baseline for estimating several demographic parameters and can be applied to other populations to allow further comparisons. Such synergistic efforts will allow a reliable definition of conservation status of this species.
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habitat preferences of guiana dolphins Sotalia guianensis cetacea delphinidae in norte bay southern brazil
Journal of the Marine Biological Association of the United Kingdom, 2010Co-Authors: Leonardo L. Wedekin, Fabio G Daurajorge, Paulo C SimoeslopesAbstract:Habitat preference and spatial distribution of Guiana dolphins (Sotalia guianensis) in Norte Bay, southern Brazil, was studied from 2001 to 2005. Boat surveys (N=91) were made to evaluate the spatial distribution of the dolphins. Seven habitat variables were integrated into a geographical information system, and habitat preference was tested using the 'Neu method' and a habitat index. The Guiana dolphins did not use all habitat types in the same proportion as were available. Areas used more intensively included, in order of importance: (1) areas with a steep sloping sea-floor; (2) areas further from urban areas; ( 3 ) areas further from mangroves; ( 4 ) areas near the mouth of the bay; ( 5 ) shallow water areas; (6) areas of clayey-silt sediments; and ( 7 ) areas close to shore. From 2001 to 2005 there was a shift in spatial distribution and habitat use by the dolphins. The low frequency of use of areas close to urban encroachment and its related impacts to the marine environment raises concern about the coastal habitat destruction. The Guiana dolphin may be considered a habitat specialist, despite its wide latitudinal distribution in the western Atlantic Ocean. The ecological niche of the species may be defined by a narrow strip of shallow coastal waters (mostly < 30 m) bordering the coastline. The shift in the spatial use was probably linked with changes in the abundance of important prey of the species and possibly was caused by the collapse of a fish stock in the study area region. Different habitats may favour different assemblages of prey and consequently different foraging strategies by the dolphins. Human-related habitat alterations throughout the range of this species are likely to affect dolphins' ecology in many ways and, thus, must be evaluated and mitigated to conserve their critical habitats.
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padroes comportamentais e intensidade de movimentos de Sotalia guianensis p j van beneden cetacea delphinidae em duas diferentes areas da costa brasileira
Revista Brasileira De Zoologia, 2007Co-Authors: Fabio G Daurajorge, Marcos R Rossisantos, Leonardo L. Wedekin, Paulo C SimoeslopesAbstract:The behavioral patterns of the estuarine dolphin, Sotalia guianensis (P. J. van Beneden, 1864), were compared between two populations along the Brazilian coast: Caravelas (Bahia), along the eastern coast, and Norte Bay (Santa Catarina), along the southern coast. Applying the focal-group sampling in both areas, information such as the geographic position (UTM) of groups and predominant behavioral patterns were obtained. Geographic positions were used to calculate the total distance traveled by estuarine dolphin groups on each observation day. Since the distance traveled varies with time, the daily mean speed of the dolphin’s group was used as an index of movement intensity. Two comparable and easily recognizable behavioral patterns were considered: travelling and foraging. Overall movement intensity and behavioral pattern frequency were similar between both areas. However, a seasonal variation was observed in both parameters in Norte Bay, while in Caravelas these parameters were homogeneous throughout the year. Variation in the behavior of the estuarine dolphin was consistent with variations in environmental factors, such as water temperature.
Leonardo Serafim Da Silveira - One of the best experts on this subject based on the ideXlab platform.
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population genetic structure of guiana dolphin Sotalia guianensis from the southwestern atlantic coast of brazil
PLOS ONE, 2017Co-Authors: Juliana Ywasaki Lima, Filipe Brum Machado, Ana Paula Cazerta Farro, Leonardo Serafim Da Silveira, Lupercio A Barbosa, Enrique MedinaacostaAbstract:Sotalia guianensis is a small dolphin that is vulnerable to anthropogenic impacts. Along the Brazilian Atlantic coast, this species is threatened with extinction. A prioritized action plan for conservation strategies relies on increased knowledge of the population. The scarcity of studies about genetic diversity and assessments of population structure for this animal have precluded effective action in the region. Here, we assessed, for the first time, the genetic differentiation at 14 microsatellite loci in 90 S. guianensis specimens stranded on the southeastern Atlantic coast of the State of Espirito Santo, Brazil. We estimated population parameters and structure, measured the significance of global gametic disequilibrium and the intensity of non-random multiallelic interallelic associations and constructed a provisional synteny map using Bos taurus, the closest terrestrial mammal with a reference genome available. All microsatellite loci were polymorphic, with at least three and a maximum of ten alleles each. Allele frequencies ranged from 0.01 to 0.97. Observed heterozygosity ranged from 0.061 to 0.701. The mean inbreeding coefficient was 0.103. Three loci were in Hardy-Weinberg disequilibrium even when missing genotypes were inferred. Although 77 of the 91 possible two-locus associations were in global gametic equilibrium, we unveiled 13 statistically significant, sign-based, non-random multiallelic interallelic associations in 10 two-locus combinations with either coupling (D' values ranging from 0.782 to 0.353) or repulsion (D' values -0.517 to -1.000) forces. Most of the interallelic associations did not involve the major alleles. Thus, for either physically or non-physically linked loci, measuring the intensity of non-random interallelic associations is important for defining the evolutionary forces at equilibrium. We uncovered a small degree of genetic differentiation (FST = 0.010; P-value = 0.463) with a hierarchical clustering into one segment containing members from the southern and northern coastal regions. The data thus support the scenario of little genetic structure in the population of S. guianensis in this geographic area.
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Population parameters and genetic diversity of microsatellite loci genotyped in Sotalia guianensis.
2017Co-Authors: Juliana Ywasaki Lima, Filipe Brum Machado, Ana Paula Cazerta Farro, Lupércio De Araújo Barbosa, Leonardo Serafim Da Silveira, Enrique Medina-acostaAbstract:Population parameters and genetic diversity of microsatellite loci genotyped in Sotalia guianensis.
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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
Brazilian journal of biology = Revista brasleira de biologia, 2016Co-Authors: Juliana Ywasaki Lima, Lupércio De Araújo Barbosa, Anna Paula Martins De Carvalho, Carolina Torres Azevedo, Leonardo Serafim Da SilveiraAbstract:Variations of age and total length of Sotalia guianensis from the state of Espirito 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.
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Ossification Pattern of Estuarine Dolphin (Sotalia guianensis) Forelimbs, from the Coast of the State of Espírito Santo, Brazil.
PloS one, 2015Co-Authors: Anna Paula Martins De Carvalho, Juliana Ywasaki Lima, Lupércio De Araújo Barbosa, Carolina Torres Azevedo, Silvina Botta, Fábio Ferreira De Queiroz, Adélia Sepúlveda Campos, Leonardo Serafim Da SilveiraAbstract:The estuarine dolphin, Sotalia guianensis, is one of the most abundant cetacean species in Brazil. Determination of age and of aspects associated with the development of this species is significant new studies. Counts of growth layer groups in dentin are used to estimate age of these animals, though other ways to evaluate development are also adopted, like the measurement of total length (TL). This study presents a procedure to evaluate the development of the estuarine dolphin based on the ossification pattern of forelimbs. Thirty-seven estuarine dolphins found in the state of Espirito Santo, Brazil, were examined. Age was estimated, TL was measured and ossification of epiphyses was examined by radiography. We analyzed results using the Spearman correlation. Inspection of radiographs allowed evaluation of the significance of the correlation between age and development of the proximal (r = 0.9109) and distal (r = 0.9092) radial epiphyses, and of the distal ulnar epiphyses (r = 0.9055). Radiographic analysis of forelimbs proved to be an appropriate method to evaluate physical maturity, and may be a helpful tool to estimate age of these animals in ecological and population studies.
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thoracic limb bone development in Sotalia guianensis van beneden 1864 along the coastline of espirito santo brazil
Journal of Mammalogy, 2015Co-Authors: Carolina Torres Azevedo, Juliana Ywasaki Lima, Raissa Miranda De Azevedo, Elitieri Batista Santos Neto, Wagner Pessanha Tamy, Lupercio A Barbosa, Jose Lailson Brito, Vanner Boere, Leonardo Serafim Da SilveiraAbstract: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 Espirito 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 e a estrutura que resta da especie Sotalia guianensis, boto-cinza, devido ao processo de decomposicao em que as carcacas sao encontradas. O objetivo do presente estudo e entender o desenvolvimento osseo dos animais encontrados encalhados no litoral do Espirito Santo. Para isso, 43 pares de nadadeiras peitorais foram submetidos as mensuracoes externas e de estruturas osseas internas (radio, ulna e umero) e a tecnica de absorciometria de raio-x de dupla energia (DEXA) para massa ossea. As variaveis das nadadeiras foram testadas pelo criterio de Akaike para escalonamento do melhor modelo de crescimento quando correlacionadas com a idade, e para o modelo alometrico quando correlacionadas com o comprimento total (CT). Foi testada a eficacia da DEXA. atraves 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 relacao ao CT. A metodologia aplicada para mensuracao da massa ossea mostrou-se eficaz quando correlacionada com peso das cinzas. Nao houve diferenca de densidade ossea entre nadadeira direita e esquerda (P > 0.05), macho e femea (P > 0.05) e nem entre os animais dos tres diferentes locais de ocorrencia, pois todos estavam dentro do mesmo intervalo de confianca. A deposicao da massa ossea e acentuada no inicio da vida com posterior estabilizacao por volta dos13 anos de idade.