INVESTIGADORES
DENUNCIO Pablo Ezequiel
congresos y reuniones científicas
Título:
Molecular identification of stranded rorquals in the northern coast of Argentina confirms the presence of Balaenoptera brydei Olsen, 1913 in the South Western Altantic Ocean
Autor/es:
RODRIGUEZ, D; MUÑOZ, G.; GIARDINO, G.; DENUNCIO, P; MANDIOLA, M.A.; DASSIS, M; BASTIDA, J; BASTIDA, R; WADA, S.
Lugar:
Florianopolis
Reunión:
Congreso; XIV Reunión de Especialistas en Mamíferos Acuáticos de América del Sur; 2010
Institución organizadora:
Solamac
Resumen:
Several factors make the identification of stranded rorquals (Cetacea: Balaenopteridae) particularly
challenging. The degree of decomposition and body position on the beach sometimes prevents ventral groove
count, colour identification or baleen inspection. Some body sizes overlap between maximum lengths of
intermediate species with medium sizes of big species. These factors result in most of the cases in a poor
assignation of species. Molecular identification of rorqual species not only have increased the possibility of
species assignments, but also have proved successful in enlightening the Family taxonomy. Although seven
balaenopterid species have been reported for the northern coast of Argentina, the strandings of these whales
are very infrequent. In the last 6 years, three strandings have been reported in the area. The first rorqual was
a male (12.7m) stranded in Mar del Sur (August 2004), and provisionally identified as a sei whale according
to ventral grooves count. The second was another male (14.7m) stranded in Mar del Plata (April 2006),
tentatively identified as a Bryde s whale based on the presence of three rostral ridges. The third one was
a 16.0m specimen stranded in Ensenada (April 2009) of unknown sex and unidentifiable species. A partial
cytochrome b gene (640 nucleotide sites from the beginning) was sequenced from skin samples of the three
specimens, and compared with 8 Balaenoptera species retrieved from the GenBank. The analysis resulted in
a positive identification of the three specimens as Balaenoptera borealis (Mar del Sur), Balaenoptera brydei
(Mar del Plata) and Balaenoptera physalus (Ensenada). The number of different nucleotides compared with
published sequences was 3, 2 and 2, respectively. To reconfirm B.brydei identification, comparisons were
made with an unpublished 416 bp Bryde's whale control region sequence from the North Atlantic Ocean
(DQ340979), resulting in a positive identification and a difference of 6 nucleotides and 2 indels. The record
of sei and fin whales in northern Argentina adds new records on existing information, but this is the first
confirmation of B.brydei inhabiting the southern SW Atlantic Ocean. Unavailable morphological diagnoses
between edeni and brydei led to conservative assignation of B.edeni to all rorquals with three rostral ridges,
leaving the correct species assignation unresolved. Our results confirm the presence of Bryde s whale in South America, but remains unclear if other morphologically identified B.edeni specimens in the region are
in fact Bryde s or Eden s whales.