15ª Reunión de Trabajo de Expertos en Mamíferos

Acuáticos de América del Sur

9º Congreso SOLAMAC

Puerto Madryn, 16 al 20 de septiembre de 2012

SOCIAL NETWORK OF GUIANA DOLPHIN (SOTALIA GUIANENSIS) IN SEPETIBA BAY, RIO DE JANEIRO SOUTHEAST BRAZIL

L.B. Campos1,2

; L. Flach2

& C.A.B. Galdino1

1 PPG- Zoologia de Vertebrados, Pontifícia Universidade Católica de Minas Gerais, Belo

Horizonte, Brasil. 2 Instituto Boto Cinza, Mangaratiba, Rio de Janeiro, Brasil.

The Guiana Dolphin Sotalia guianensis is a small cetacean that inhabits south america's coast. Like other dolphin species it lives in a society with high fission-fusion patterns. The present work studies the social network from the population of Sotalia guianensis in Sepetiba Bay, in Rio de Janeiro state, southeast Brazil. We used photo-identification to indentify the individuals. The associations between the dolphins were recorded for 4 years (2006 - 2009). The society of S. guianensis in Sepetiba Bay forms a closed network, all the individuals interact with each other. There are preferred companionships. The network was formed by 34 nodes (individuals), connected by 654 edges (associations) with a mean association index of 0.29. The number of interactions (density ρ = 0.55) shows that we found a loosely connected network (mean degree k = 18.68) with not too strong associations (mean strongnesss = 2.985 ± 1.255) and not very centralized ( network centralization = 34,25%). The global clustering coefficient was Cw,am = 0.683, and the closeness level was high (Closeness = 69,722). Some individuals showed a great level of centrality (Degree e Betweenneess > 70) which can refer to the importance of this animals in this society.