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

Abstract

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,

Occurrence and distribution patterns of several marine vertebrates in Golfo Dulce, Costa Rica

“…S. attenuata was recorded at 42 sightings, representing approximately 1 574 dolphins. Habitat partitioning as described by Acevedo-Gutiérrez and Burkhart (1998), Cubero-Pardo (2007) and Oviedo (2007) was evident between these resident delphinids; T. truncatus, found in all quadrants, tended to be coastally aligned with sighting densities near the large river outlets, while S. attenuata, often observed in larger fission-fusion grouping patterns, was found in central waters from GA2-GA5, but not in GA1. Both species were seen foraging, traveling, and socializing with calves (Bessesen, 2012, unpublished).…”

“…The North Pacific population arrives in the Eastern Tropical Pacific (ETP) during the boreal winter (December-March, Costa Rican dry season) and the Southern Hemisphere population arrives in the ETP during austral winter (July-October, Costa Rican rainy season). Tursiops truncatus (Montagu, 1821) and Stenella attenuata (Gray, 1846) reside sympatrically within the embayment (Acevedo-Gutiérrez & Burkhart, 1998;Cubero-Pardo, 2007;Oviedo, 2007) although other delphinids, including Pseudorca crassidens (Owen, 1846) occasionally enter the habitat (Acevedo-Gutierrez, Brennan, Rodriguez & Thomas, 1997). Sea turtles, Chelonia mydas (Linnaeus, 1758), Lepidochelys olivacea (Eschscholtz, 1829), Eretmochelys imbricata (Linnaeus, 1766), and Dermochelys coriacea (Vandelli, 1761) have been reported around the Osa Peninsula (Quesada-Alpízar, Cortés-Núñez, Alvarado & Fonseca, 2006).…”

Registros de varamientos de cetáceos en El Salvador entre 1995-2019

“…Las especies más frecuentemente varadas tienen hábitos costeros (Tursiops truncatus) y costerooceánicos (Stenella attenuata), que se asocian con variables relacionadas a la distancia a la costa, la profundidad, la temperatura y oleaje en sus patrones de alimentación y socialización (Cubero-Pardo, 2007). En Nicaragua se documentó relación positiva de la ocurrencia de Stenella attenuata, Tursiops truncatus y Megaptera novaeangliae con factores como temperatura del agua y la distancia a la costa (Abarca et al, 2016).…”

“…En el océano Pacífico Oriental en general, se registra una importante diversidad de cetáceos ( Jefferson et al, 1993), relacionada con factores oceanográficos (Cubero-Pardo, 2007;McLeod, 2009), irregularidades de la costa y tipo de fondo marino (Cabrera et al, 2014), temperatura del agua (Abarca et al, 2016), distribución de las presas, abundancia y diversidad de alimento (MARN, 2017).…”

Diversidad de cetáceos en el paisaje marino costeros de Golfo Dulce, Península de Osa, Costa Rica

“…Golfo Dulce es una de las áreas de estudio en Costa Rica con mayor productividad académica en trabajos pertinentes a ecología de cetáceos (Acevedo & Smultea, 1995;Acevedo-Gutiérrez, 1996;Acevedo-Gutiérrez & Burkhart, 1998;Cubero-Pardo, 1998;Acevedo-Gutiérrez & Matthews, 2005;Cubero-Pardo, 2007a;Cubero-Pardo, 2007b;Oviedo, 2007;Pacheco-Polanco & Oviedo, 2007;Oviedo, 2008;Oviedo, Pacheco & Herra-Miranda, 2009;Pacheco-Polanco, Oviedo, Herra-Miranda & Silva, 2011;Márquez-Artavia et al, 2012;Oviedo et al, 2012;Bessesen et al, 2014), esto debido a los atributos fisiográficos y estructurales de este importante hábitat marino-costero, que lo hacen un excelente laboratorio natural para el estudio de cetáceos. Los retos metodológicos y logísticos del trabajo con mamíferos marinos, en áreas donde los limites son más fluidos que fijos, son facilitados notablemente en Golfo Dulce, lo que incide en la efectividad de la colecta de observaciones con mayor resolución, así como en la potencialidad para estudios a largo plazo.…”