[MARMAM] New publication about Group structure of Sotalia guianensis in Ilha Grande Bay, Southeastern Brazil

Rodrigo Tardin rhtardin at gmail.com
Thu Apr 25 13:14:22 PDT 2013


Hi all,

We are please to announce the following publication in Latin American
Journal of Aquatic Research (LAJAR):

Tardin R., Galvão C., Espécie M., Simão S.
Group structure of Guiana dolphins, Sotalia guianensis (Cetacea,
Delphinidae)
in Ilha Grande Bay, Rio de Janeiro, southeastern Brazil

Abstract:
ABSTRACT.  Cetaceans  present  a  group  structure  of  great  complexity
 and  display  a  wide  behavioral plasticity. Many efforts have been made
to understand the group structures of the various species, however, this
type of information is still lacking for some species. Therefore, our
objectives were to 1) characterize the
structure of the Sotalia guianensis groups in Ilha Grande Bay, Rio de
Janeiro, Brazil, and 2) investigate how both  behavior  and  season
 influence  the  group  structure  of  this  population.  This  species  is
 considered  “data deficient” by the IUCN. We conducted 28 boat trips using
group focal procedures, and a total of 1,314 groups were observed. Of these
groups, 1,268 (94.4%) contained calves, the largest percentage ever
reported for the species.  Groups  with  calves  were  larger  than  those
 without  them,  suggesting  a  strategy  to  protect  these
individuals with underdeveloped physiology. The mean group sizes reached
17.6 ± 18.3 individuals. Within these  groups,  we  observed  that  both
 behavior  (H  =  112.5,  d.f.  =  2,  P  <  0.05)  and  season  (number
 of simulations:  10,000;  sample  size  of  fall-winter  =  544;  sample
 size  of  spring-summer  =  684;  P  <  0.05), demonstrated  a
 statistically  significant  influence.  The  most  common  degree  of
 cohesion  was  mixed,  and cohesion  also  varied  with  behavior  (χ²  =
 10.1,  P  <  0.05)  and  season  (χ²  =  31.0,  P  <  0.05).  This  paper
contributes towards understanding the highly variable nature of S.
guianensis group dynamics. These data may be important in understanding the
structure of groups in a site that is being increasingly impacted by
different human activities. Moreover, this area contains the largest
aggregation ever observed for this species and may therefore represent an
important source of genetic diversity for the species as a whole.

For pdf copies please contact me or retrieve in the folowing website:
http://www.lajar.cl/det_en.php?id=58

Best regards,
Rodrigo

-- 
Rodrigo Tardin

Doutorando em Ecologia e Conservação - IBRAG - UERJ
Mestre em Biologia Animal - PPGBA - UFRRJ
Especialista em Docência do Ensino Superior - IAVM
Laboratório de Bioacústica e Ecologia de Cetáceos - UFRRJ/ IF/ DCA
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