Distribución espacial, estructura social y amenazas de conservación de una pequeña comunidad de delfines nariz de botella, Tursiops trunca (Odontoceti: Delphinidae) en Ecuador

Una comunidad residente de bufeos costeros Tursiops truncatus ha sido estudiada de manera intermitente entre 2005 y 2018 en la punta de la península de Santa Elena, Ecuador (2°11' S & 81°0.7' W). Avistamientos oportunistas y dirigidos desde la playa y abordo de un bote con motor fuera de borda se realizaron a lo largo de 40 km de costa, contabilizándose un esfuerzo de 917.2 km de seguimiento en automóvil desde tierra y 707.4 km en bote por mar. El tamaño grupal promedio fue 5.31 delfines/grupo (SD = 1.97, rango 1-10), sin cambios significativos a lo largo del estudio. Desde tierra el tamaño grupal fue subestimado en promedio en 32 %. Esta comunidad de bufeos tiene actualmente solo nueve individuos, incluyendo seis adultos, un inmaduro y dos crías, siendo la comunidad más pequeña encontrada en el golfo de Guayaquil. La tasa de encuentro varió entre 0.03 delfines/km en la parte noroeste y 0.31 delfines/km en la parte sur, donde los delfines concentran sus actividades, posiblemente porque las actividades humanas ahí son menos intensas. Los delfines se distribuyeron generalmente entre los primeros 200 m de la orilla llegando hasta 1 200 m en la parte norte donde la profundidad es menor y las actividades portuaria y turística más intensas. La velocidad de los delfines fue significativamente más alta cuando fueron seguidos desde un bote a corta distancia (5.87 km/h) que cuando fueron monitoreados desde tierra (2.9 km/h) (P < 0.01), lo cual sugiere que el seguimiento en bote tuvo un impacto sobre el movimiento de los delfines. Un análisis clúster jerárquico mostró que los delfines tienen altos índices de asociación entre ellos (promedio 0.67, rango 0.01-1.0), indicando que es una comunidad altamente cohesionada. Adicionalmente muestran un alto nivel de residencia (índice de ocurrencia promedio de 0.62). Durante el estudio se identificaron dos amenazas principales, una pesquería con redes agalleras en la parte suroeste y un intenso tráfico de botes pesqueros en la parte noroeste. La mayoría del área de estudio actualmente es parte de un área costero-marina protegida creada en 2008, lo cual ofrece una oportunidad para la recuperación de esta comunidad de delfines. Debido a su fragilidad, se recomienda a las autoridades ambientales, entre otras cosas, eliminar potenciales fuentes de amenaza para los delfines como las redes de pesca, implementar un área de exclusión para artes de pesca y tráfico de botes pesqueros de 1 km de ancho desde la orilla y limitar la velocidad de todo tipo de embarcación a 10 nudos dentro del área protegida.

A resident community of bottlenose dolphins (Tursiops truncatus) has been studied irregularly between 2005 and 2018 around the tip of the Santa Elena Peninsula, Ecuador (2°11' S & 81°0.7' W). Opportunistic sightings and systematic surveys from the beach and at sea were carried out along 40 km of coast, accounting for 917.2 km of tracking by car from land and 707.4 km of boat tracking by sea. Average group size was 5.31 dolphins/group (SD = 1.97, range 1-10), with no significant changes throughout the study period. From land, however, the group size was underestimated 32 % on the average. This small bottlenose dolphin community currently has only nine individuals, including six adults, one immature and two calves, and is the smallest community within the Gulf of Guayaquil. The encounter rate ranged between 0.03 dolphins/km in the northwestern part and 0.32 dolphins/km in the South, where dolphins concentrate their activities, possibly because human activities are less intense there. Dolphins were generally distributed in the first 200 m from the shore, reaching up to 1 200 m in the Northern shallower part and where port and tourist activities concentrate. The dolphins' speed was significantly higher when they were followed from a boat at close range (5.87 km/h) than when they were monitored from the beach (2.9 km/h) (P < 0.01), which suggests that boat tracking had an effect on dolphin´s movements. Pairwise cluster analysis showed that animals from this community show high rates of association among each other (average 0.67, range 0.01-1.0), indicating that is a highly cohesive community. Dolphins also showed high level of residence (average occurrence index = 0.62). During the study, two main threats were identified, a gillnet fishery in the Southwestern part and an intense fishing boat traffic in the Northwestern. Most of the study area is currently part of a coastal-marine protected area created in 2008, which offers an opportunity for the recovery and conservation of this dolphin community. Given its fragility, we recommend the environmental authorities to address potential threats for this dolphin community by eliminating gillnets, implementing an exclusion zone for fishing gear and boat traffic of 1 km width from the shore and limit the speed of any type of vessel to 10 knots within the reserve.

Cetacean records along a coastal-offshore gradient in the Vitória-Trindade Chain, western South Atlantic Ocean / Registros de cetáceos ao longo de um gradiente costeiro-pelágico na Cadeia Vitória-Trindade, Oceano Atlântico Sul ocidental

Oceanic waters are difficult to assess, and there are many gaps in knowledge regarding cetacean occurrence. To fill some of these gaps, this article provides important cetacean records obtained in the winter of 2010 during a dedicated expedition to collect visual and acoustic information in the Vitória-Trindade seamounts. We observed 19 groups of cetaceans along a 1300-km search trajectory, with six species being identified: the humpback whale (Megaptera novaeangliae, N = 9 groups), the fin whale (Balaenoptera physalus, N = 1), the Antarctic minke whale (Balaenoptera bonaerensis, N = 1), the rough-toothed dolphin (Steno bredanensis, N = 1), the bottlenose dolphin (Tursiops truncatus, N = 2), and the killer whale (Orcinus orca, N = 1). Most humpback whale groups (N = 7; 78%) were observed in the Vitória-Trindade seamounts, especially the mounts close to the Abrolhos Bank. Only one lone humpback whale was observed near Trindade Island after a search effort encompassing more than 520 km. From a total of 28 acoustic stations, humpback whale songs were only detected near the seamounts close to the Abrolhos Bank, where most groups of this species were visually detected (including a competitive group and groups with calves). The presence of humpback whales at the Trindade Island and surroundings is most likely occasional, with few sightings and low density. Finally, we observed a significant number of humpback whales along the seamounts close to the Abrolhos Bank, which may function as a breeding habitat for this species. We also added important records regarding the occurrence of cetaceans in these mounts and in the Western South Atlantic, including the endangered fin whale.

Águas oceânicas e afastadas da costa são ambientes de difícil acesso e muitas lacunas de conhecimento sobre a ocorrência de cetáceos ainda existem. O presente trabalho fornece importantes registros realizados durante uma expedição dedicada a procurar cetáceos visualmente e acusticamente na Cadeia Vitória-Trindade no inverno de 2010. Foram observados 19 grupos de cetáceos ao longo de 1300 km de esforço, sendo identificadas seis espécies: a baleia-jubarte (Megaptera novaeangliae, N = 9 grupos), a baleia-fin (Balaenoptera physalus, N = 1), um grupo misto de baleia-minke-Antártica (Balaenoptera bonaerensis) e golfinhos-de-dentes-rugosos (Steno bredanensis, N = 1), o golfinho-nariz-de-garrafa (Tursiops truncatus, N = 2) e a orca (Orcinus orca, N = 1). A maioria dos grupos da baleia-jubarte (n=7; 78%) foram observados nos montes marinhos da Cadeia Vitória-Trindade, especialmente os montes próximos do Banco dos Abrolhos. Somente uma baleia-jubarte solitária foi observada próxima da Ilha Trindade, apesar de mais de 520 km percorridos em esforço na região. De um total de 28 estações acústicas, cantos da baleia-jubarte foram detectados somente nos montes próximos ao Banco dos Abrolhos, onde a maioria dos grupos desta espécie foi observada visualmente (incluindo grupos competitivos e fêmeas com filhotes). A presença da baleia-jubarte nos arredores da Ilha de Trindade é provavelmente ocasional, com poucos indivíduos e baixa densidade. Finalmente, um número expressivo de grupos de baleia-jubarte foi observado sobre os montes próximos do Banco dos Abrolhos, que podem funcionar como habitats reprodutivos da espécie. Adicionaram-se ainda importantes registros de cetáceos na Cadeia Vitória-Trindade e no Oceano Atlântico Sul ocidental, incluindo a baleia-fin, uma espécie ameaçada de extinção.

Comportamiento de mantenimiento y niveles de cortisol de toninas (Tursiops truncatus) en instalaciones cerradas y abiertas / Maintenance behaviour and cortisol levels in bottlenose dolphins (Tursiops truncates) in closed and open facilities

Few studies have been published regarding the influence of the environment on the behaviour and welfare of captive dolphins and most of them have been in closed facilities. The aim of this study was to assess the time budget in fast and slow swimming, counter clockwise and clockwise swimming, as well as the state of rest in dolphins staying in closed and open facilities in daytime and evening hours. In addition, to give further information about the welfare state between dolphins in closed and open facilities, serum cortisol levels were compared. Six dolphins Tursiops truncatus in open facilities and four dolphins of the same species in closed facilities were used. There by, a focal sampling was used to obtain the data; 36 hours observing in open facilities and 48 in closed ones. Twenty blood samples were obtained from the ten dolphins in order to measure the serum cortisol, using radioimmunoassay. The locomotion bouts in swimming were higher in open facilities than in closed dolphinariums (P < 0.05); additionally, the outcome showed higher time in fast clockwise swimming (P < 0.05) with dolphins staying in open facilities, and more resting time (P < 0.05) in closed dolphinariums. There were no differences in the average level of cortisol between both facilities (P > 0.05). The outcome obtained in this study helped to know how dolphins face up captivity in two kinds of facilities, and so to improve care and management.

Pocos estudios han sido publicados acerca del efecto del ambiente sobre el comportamiento y bienestar en delfines cautivos, la mayor parte de éstos se ha generado en instalaciones cerradas. El objetivo del presente estudio fue calcular la proporción de tiempo de los nados rápido y lento a favor y en contra de las manecillas del reloj, y reposo de toninas alojadas en instalaciones abiertas y cerradas en horarios diurno y nocturno. Además, se compararon los niveles de cortisol sérico entre delfines alojados en instalaciones cerradas y abiertas con el fin de ampliar la información acerca de indicadores de bienestar. Se utilizaron 6 delfines de la especie Tursiops truncatus en instalaciones abiertas y 4 en instalaciones cerradas. Para la obtención de datos se usó un muestreo focal que ocupó 36 horas de observación en instalaciones abiertas y 48 en las cerradas. Para la determinación de cortisol sérico a través de radioinmunoanálisis se tomaron 20 muestras seriadas de sangre de los diez delfines. Los intervalos continuos de conducta de nado tuvieron una mayor frecuencia en instalaciones abiertas que en las cerradas (P < 0.05). Además, los resultados mostraron mayor tiempo de nado a favor de las manecillas del reloj rápido (P < 0.05) en delfines alojados en instalaciones abiertas, así como más tiempo de reposo (P < 0.05) en instalaciones cerradas. No hubo diferencias en los niveles promedio del cortisol entre instalaciones (P > 0.05). Los resultados obtenidos en este estudio contribuyen al conocimiento de cómo enfrentan las toninas el cautiverio en dos tipos de instalaciones, para mejorar su cuidado y manejo.

Comportamiento social e individual de un grupo de toninas (Tursiops truncatus) en instalaciones abiertas y cerradas / Social and individual behavior of a group of bottlenose dolphins (Tursiops truncatus) in open and closed facilities

Few studies on the welfare of captive bottlenose dolphins (Tursiops truncatus) have been carried out. Of these, most include information on animals kept in closed facilities or pools. The aim of this study was to assess the effect on the behavior of a group of dolphins by changing it from closed facilities, where it had been housed for nine years, to open facilities or sea pens. Ten bottlenose dolphins (Tursiops truncatus), one male and nine females, with an age range of 16 to 24 years were observed. Using a combination of scan and focal sampling a total of 96 hours were used to obtain information on the proportion of time on individual and social behaviors in both type of facilities. The results show that dolphins kept in closed facilities spent less time swimming and more time floating than in open facilities (P = 0.01). Likewise, the swimming pattern in closed facilities is in circles (P = 0.009) while in open facilities the linear pattern predominates (P = 0.02). Furthermore, while kept in closed facilities, dolphins spent more time interacting socially than in open facilities (P = 0.02). This information is useful to better understand the effect of different types of facilities on the behavior of captive dolphins.

Existen pocos estudios respecto del comportamiento de toninas (Tursiops truncatus) en cautiverio, la mayoría se ha hecho con animales alojados en albercas o en instalaciones cerradas. El objetivo de este estudio fue evaluar el efecto que produce en el comportamiento de un grupo de toninas que habían estado alojadas durante nueve años, desde que fueron capturados en aguas abiertas, el cambio de un estanque en el mar a instalaciones cerradas o albercas. Se observaron diez toninas (Tursiops truncatus), un macho y nueve hembras, con rango de edades de 16 a 24 años. A través de una combinación de muestreos focales y de barridos se obtuvo un total de 96 horas de observación de comportamiento, para obtener información sobre la proporción del tiempo en comportamientos individuales y sociales en ambos tipos de instalaciones. Los resultados muestran que los animales en instalaciones cerradas nadan en promedio menos tiempo y dedican más tiempo a flotar que en instalaciones abiertas (P = 0.01). Asimismo, el patrón de nado en instalaciones cerradas es circular (P = 0.009) mientras que en instalaciones abiertas es predominantemente lineal (P = 0.02). También se observó que los animales, al estar en instalaciones cerradas, dedican más tiempo a interactuar socialmente que en lugares abiertos (P = 0.02). Esta información es útil para entender mejor el efecto de diferentes tipos de instalaciones sobre el comportamiento de animales en cautiverio.

Estimates of DNA strand breakage in bottlenose dolphin (Tursiops truncatus) leukocytes measured with the Comet and DNA diffusion assays

The analysis of DNA damage by mean of Comet or single cell gel electrophoresis (SCGE) assay has been commonly used to assess genotoxic impact in aquatic animals being able to detect exposure to low concentrations of contaminants in a wide range of species. The aims of this work were 1) to evaluate the usefulness of the Comet to detect DNA strand breakage in dolphin leukocytes, 2) to use the DNA diffusion assay to determine the amount of DNA strand breakage associated with apoptosis or necrosis, and 3) to determine the proportion of DNA strand breakage that was unrelated to apoptosis and necrosis. Significant intra-individual variation was observed in all of the estimates of DNA damage. DNA strand breakage was overestimated because a considerable amount (~29 percent) of the DNA damage was derived from apoptosis and necrosis. The remaining DNA damage in dolphin leukocytes was caused by factors unrelated to apoptosis and necrosis. These results indicate that the DNA diffusion assay is a complementary tool that can be used together with the Comet assay to assess DNA damage in bottlenose dolphins

Movements of the bottlenose Dolphin (Tursiops truncatus) in the Rio de Janeiro State, Southeastern Brazil / Deslocamentos do golfinho-nariz-de-garrafa (Tursiops truncatus) no estado do Rio de Janeiro, sudeste do Brasil

Aiming to verify the movements of the bottlenose dolphin (Tursiops truncatus) at Rio de Janeiro State coast, southeastern Brazil, we performed a photoidentification comparison between the catalogued individuals of the Cagarras Archipelago (23º 02' S and 43º 12' W) in 2004 and 2006 (n = 26) and the images obtained (n = 179) during the Southeastern Cetaceans Expedition, conducted during months of June and November of 2005. Eight individuals (three females and five dolphins of unknown gender) identified in the Cagarras Archipelago were resighted in the Grande Island (23º 21'S and 44º 15' W), about 100 km southwestwards from Cagarras Archipelago. The observed movements include distances commonly recorded for the species elsewhere and are probably related to search for prey.

Com o objetivo de verificar os deslocamentos do golfinho-nariz-de-garrafa (Tursiops truncatus) no estado do Rio de Janeiro, sudeste do Brasil, foi feita uma análise entre os indivíduos catalogados no arquipélago das Cagarras em 2004 e 2006 (n = 26) e as fotografias (n = 179) obtidas durante a Expedição Cetáceos do Sudeste, realizada em junho e novembro de 2005. Oito indivíduos (três fêmeas e cinco golfinhos de sexo indeterminado) identificados no arquipélago das Cagarras (23º 02' S e 43º 12' W) foram reavistados na Ilha Grande (23º 21'S e 44º 15' W), aproximadamente 100 km a sudoeste do arquipélago. Os deslocamentos observados estão dentro das distâncias comumente registradas para a espécie e, provavelmente, são relacionados com a busca de recursos alimentares.

Notas sobre a distribuição, tamanho de grupo e comportamento do golfinho Tursiops truncatus (Cetacea: Delphinidae) na Ilha de Santa Catarina, sul do Brasil / Notes on the distribution, group size and behavior of the bottlenose dolphin,Tursiops truncatus(Cetacea: Delphinidae) in the coast of the Island of Santa Catarina, southern Brazil

A ecologia do golfinho-nariz-de-garrafa (Tursiops truncatus) é pouco documentada no Brasil. O objetivo deste trabalho é fornecer dados sobre a distribuição, tamanho de grupo e comportamento de T. truncatus a partir de avistagens oportunistas realizadas nas adjacências da Ilha de Santa Catarina, sul do Brasil. Em cada observação de grupos da espécie foram registrados: localidade, data e hora, tamanho de grupo e comportamento. Foram observados 71 grupos entre 1989 e 2005, em todos os meses do ano. A espécie foi observada em toda região costeira da Ilha de Santa Catarina, utilizando uma grande variedade de hábitats. O tamanho de grupo variou entre 1 e 200 indivíduos, com uma média de aproximadamente 8 indivíduos (moda = 2). Interações com pelo menos três espécies de aves marinhas também foram observadas, além de outros comportamentos. Os dados obtidos sugerem que a espécie é comum ao longo da costa da Ilha de Santa Catarina, possui uma grande plasticidade no uso de hábitats, além de um conjunto variado de comportamentos.

The ecology of the bottlenose dolphin (Tursiops truncatus) is scarcely documented in Brazil. The objective of this article is to present information about the distribution, group size and behavior of T. truncatus collected oportunistically around the Island of Santa Catarina. Locality, date and time, group size and behavior were registered after each opportunistic sighting. Seventy-one groups were observed between 1989 and 2005, in all months of the year. The species was sighted along all the coast of the island, using a great variety of habitats including protected bays and exposed beaches. Group size varied from 1 to 200 individuals, with a mean group size of approximately 8 individuals (mode = 2). Interactions with three species of sea birds were also documented. Data presented here suggest that the species is common around the Island of Santa Catarina, has a great plasticity in habitat use, and a varied behavior repertoire.

Distribución y condiciones ambientales asociadas al comportamiento del delfín bufeo (Tursiops truncatus) y el delfín manchado (Stenella attenuata) (Cetacea: Delphinidae) en el Golfo Dulce, Costa Rica

Distribution and environmental conditions related to the behavior in the bottlenose dolphin (Tursiops truncatus) and the spotted dolphin (Stenella attenuata) (Cetacea: Delphinidae) in Golfo Dulce, Costa Rica. Habitat characteristics influencing behavior in animal species vary locally. The influence that a particular environmental characteristic can have on a species depends not only on other variables, but on morphological, physiological and social conditions of that species. in this study, developed from June 1996 to July 1997, I studied whether specific behaviors are related to particular distribution areas and environmental factors in the bottlenose (Tursiops truncatus) and the spotted dolphin (Stenella attenuata). The study area was covered along oblicuous linear transects, and the behavior of single groups was observed from 15 min to 5 h. Environmental factors such as depth, temperature, salinity and distance from shore, among others, were considered. For the bottlenose dolphin, foraging/feeding activities showed exclusive coincidence with river mouths, coral reef and mangrove areas, while social and milling activities where seen close to feeding areas. Traveling occurred along different points parallel to the coast, with a low percentage of cases across the gulf (16.56 %), suggesting that the bottlenose rarely crosses from one side to the other. in the spotted dolphin, several behaviors were observed simultaneously in the schools and it was not possible to associate areas with particular behaviors. The lack of significant relationships among activities and particular environmental variables (ANOVA tests) is attributed to three aspects: (a) transitions among activities generally occurred into a low variable area, (b) dolphins often traveled along large areas without changing activities and (c) environmental conditions in Golfo Dulce are homogeneous. in the two species the highest average in the number of individuals per group corresponded to the category of active socializing, followed by traveling, passive socializing and feeding. in the case of the bottlenose dolphin, the smallest group size was associated with feeding activities (ANOvA, F= 2.624, p=0.037, n= 156, df= 4), while in the spotted dolphin the smallest group size corresponded to milling activities (ANOvA, F= 3.817, p=0.009, n=51, df= 4). Rev. Biol. Trop. 55 (2): 549-557. Epub 2007 June, 29.

Las características del hábitat que influyen en las especies animales varían de un lugar a otro. Al mismo tiempo, toda especie es rodeada por una serie de factores ambientales que interactúan entre sí, pero la influencia que una característica ambiental particular pueda ejercer sobre una especie depende no sólo de las demás variables, sino de las condiciones morfológicas, fisiológicas y sociales de esa especie. En este estudio, desarrollado de junio 1996 a julio 1997, la pregunta fue enfocada a determinar si comportamientos específicos en el delfín bufeo (Tursiops truncatus) y el delfín manchado (Stenella attenuata) están relacionados con áreas de distribución y factores ambientales particulares. El área de estudio fue cubierta siguiendo transectos lineares oblicuos predeterminados y cada grupo fue observado de 15 min a 5 h. Las variables ambientales fueron medidas al inicio y al final de cada avistamiento junto con la determinación de la posición geográfica y el comportamiento llevado a cabo por los delfines. Para el bufeo, las actividades de forrajeo/ alimentación mostraron coincidencia exclusiva con bocas de ríos y áreas de coral y manglar, y las actividades sociales y de merodeo, se asociaron a áreas cercanas a los sitios de forrajeo. El desplazamiento ocurrió a lo largo de diferentes puntos paralelos a la costa, con un bajo porcentaje de casos a través del golfo (16.56 %), lo cual sugiere que el bufeo rara vez cruza el golfo. En el caso del manchado, no fue posible asociar zonas comportamientos particulares, pues todo el grupo se mueve junto; sin embargo, si fue observada la presencia de distintos comportamientos en un mismo momento, llevados a cabo por grupos específicos dentro de la manada. Se consideraron factores ambientales tales como la profundidad, la temperatura, la salinidad y la distancia respecto a la costa, entre otros. El ANDEVA de bloques no reveló una relación marcada entre actividades y zonas variables ambientales particulares, sin embargo, los resultados mostraron información valiosa sobre tendencias muy interesantes. La falta de significancia, en relación con los aspectos ambientales, fue atribuida a tres aspectos: (a) las transiciones entre actividades se dieron generalmente dentro de un área poco variable, (b) fue común que los delfines se desplazaran cubriendo grandes áreas sin cambiar de actividad y (c) las condiciones ambientales en el Golfo son bastante homogéneas. En ambas especies el mayor promedio en el número de individuos por grupo correspondió a la categoría de socialización activa, seguido en forma decreciente por el desplazamiento, la socialización pasiva y la alimentación. En el caso del bufeo, el menor tamaño promedio de grupo estuvo asociado a las actividades de alimentación (ANDEVA, F= 2.624, p=0.037, gl= 4), mientras que en el manchado correspondió a los momentos de merodeo (ANDEvA, F= 3.817, p=0.009, gl= 4).