C. Campagna (a,b,*), A.R. Piola (c,d), M.R. Marin (a), M. Lewis (a), and T. Fernández (a)
a) Centro Nacional Patagónico,
Consejo Nacional de Investigaciones Científicas y Técnicas
(CONICET), (9120), Puerto Madryn, Chubut, Argentina
b) Wildlife Conservation
Society, 2300 Southern Blvd., Bronx NY 10460, USA.
c) Departamento de Oceanografía,
Servicio de Hidrograf_a Naval, Av. Montes de Oca 2124, (1271), Buenos Aires,
Argentina.
d) Departamento de Ciencias
de la Amósfera y los Océanos, Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Argentina.
Deep-Sea Research I, 53:1907-1924. (2006)
This study describes the association between transient,mesoscale hydrographic features along the axis of the Brazil –Malvinas Confluence, in the SW Atlantic, and the foraging behavior of 2 –3-year-old (focal) juvenile southern elephant seals, Mirounga leonina from Peninsula Valdés, Argentina. Departing from the dominant pattern of foraging on predictable bathymetric fronts on the Patagonian shelf and slope, three females out of 12 satellite-tracked juveniles remained at the edge of young warm-core eddies and near the outer core of cold-core eddies, coinciding with the most productive areas of these temperature fronts. Seal trajectories along high-temperature gradients were always consistent with the speed and direction of surface currents inferred from the temperature distribution and confirrmed by surface drifters. Movements of foraging seals were compared with those of surface drifters, coinciding in time and space and yielding independent and consistent data on regional water circulation parameters. The diving pattern recorded for one focal seal yielded shallower dives and a loose diel pattern in the eddy, and a marked diurnal cycle compatible with foraging on vertically migrating prey in the cold waters of the Malvinas Current. Pre-reproductive females that use the mesoscale fronts of the Argentine Basin as an alternative foraging area would benefit from lower competition with more experienced seals and with other top predators that reproduce along the coast of Patagonia.
Keywords: Foraging behavior ;Telemetry; Oceanic fronts; Eddies (oceanic); Mirounga leonina Temporal distribution
*) Corresponding author:
Centro Nacional Patagónico, Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET), (9120) Puerto Madryn, Chubut,
Argentina.
Tel.: +54 2965 451375;
fax: +54 2965 451543.
E-mail address: ccvz_puertomadryn@speedy.com.ar
(C.Campagna).