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Crespo E.A.,CONICET | Crespo E.A.,Brown University | Schiavini A.C.M.,CONICET | Garcia N.A.,CONICET | And 5 more authors.
Marine Mammal Science | Year: 2015

The South American fur seal (SAFS), Arctocephalus australis, was severely depleted during the 18th century. This work updates information on distribution, abundance, seasonal movements, and genetic structure along the southwestern South Atlantic. Its distribution in Argentine waters includes nineteen rookeries on the Patagonian coast, Isla de los Estados, and islets of the Beagle Channel. Censuses were carried out in rookeries from Isla Escondida to Isla de los Estados from 1996 to 2014. The largest concentrations are found in Chubut, (4,500-15,500 seals) and Isla de los Estados (4,500). Pups were recorded on Isla Escondida, Rasa, and Isla de los Estados. An increasing number of SAFS were recorded in northern Patagonia, including seals marked in Uruguay. Skin samples were taken from southern Brazil to Tierra del Fuego in order to evaluate population structure and demographic trends. Genetic results indicated no population subdivisions (Φst = -0.0292, Fst = -0.00716, P > 0.05). Bayesian skyline plots constructed for the entire data set indicated evidence of rapid population expansion discernible in Nef between the last 20,000 and 17,000 yr. Genetics results and observation data from marked fur seals support the hypothesis of ancient gene flow and a single Atlantic population. Therefore, SAFS should be managed under international and integrated conservation policies. © 2015 Society for Marine Mammalogy.

Orgeira J.L.,Instituto Antartico Argentino | Scioscia G.,CONICET | Torres M.A.,Museo Acatushun de Aves y Mamiferos Marinos Australes | Dellabianca N.A.,CONICET
Polar Research | Year: 2013

During ship-based seabird surveys in the south Atlantic and Antarctica in the austral summers of 1994/95, 2009, 2010, 2011 and 2012, we documented at-sea distributions of Buller's albatross (Thalassarche bulleri), Atlantic petrel (Pterodroma incerta), soft-plumaged petrel (Pterodroma mollis), Kerguelen petrel (Lugensa brevirostris) and great-winged petrel (Pterodroma macroptera). In some cases, sightings were considered as extralimital, but for other species updating their distributions in the literature seems warranted. Atlantic petrel, for example, has been regularly observed in the Drake Passage and north of the Antarctic Peninsula for about 30 years, but the distribution of this species has not been updated in the literature. The observations reported here will contribute to update the at-sea distributions of these species and to changes in their distributions. © 2013 J.L. Orgeira et al.

Zenteno L.,University of Barcelona | Crespo E.,CONICET | Crespo E.,National University of Patagonia | Goodall N.,Museo Acatushun de Aves y Mamiferos Marinos Australes | And 8 more authors.
Journal of Zoology | Year: 2013

Stable isotopes of oxygen have been widely used to reconstruct paleotemperatures and to investigate the thermal environment of fishes and mollusks, but they have only occasionally been used as geographical markers in marine systems. As bone apatite grows at a constant temperature in marine mammals and food is the major source of water for these animals, particularly for pinnipeds, variations in the ratio of stable isotopes of oxygen (δ18O) of bone apatite will likely reflect changes in the δ18O values of diet, and thus of the surrounding water mass, despite the potential confounding role of factors as the proximate composition of diet, sex and body size. Here, we used the δ18O values in bone apatite to investigate whether adult males of South American sea lion (Otaria byronia), from three regions in southwestern Atlantic Ocean (Brazil, Patagonia and Tierra del Fuego in Argentina), used the same water masses to forage and whether differences exist in the water masses used by sea lions differing according to sex and developmental stage. Statistically significant differences were observed among the δ18O bone values of adult males from the three regions, with those from Patagonia more enriched in 18O, as expected from the δ18Oseawater values. These results revealed restricted dispersal movements of adult males between the three areas. On the other hand, adult males and females from Patagonia did not differ in average δ18Obone values, thus indicating the use of foraging grounds within the same water mass. Finally, the variability in the δ18Obone values of young of both sexes was much wider than the adults of the same sex from the same region, which suggests the existence of a juvenile dispersal phase in both sexes, although much shorter in females than in males. These results confirm the usefulness of stable isotopes of oxygen as habitats tracers in marine mammals. © 2013 The Zoological Society of London.

Caceres-Saez I.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Goodall R.N.P.,Museo Acatushun de Aves y Mamiferos Marinos Australes | Goodall R.N.P.,CONICET | Dellabianca N.A.,Museo Acatushun de Aves y Mamiferos Marinos Australes | And 4 more authors.
Chemosphere | Year: 2015

The skin of bycaught Commerson's dolphins was tested for mercury (Hg) and selenium (Se) biomonitoring in Subantarctic environments. The correlation of levels detected in the skin with those found in internal tissues - lung, liver, kidney and muscle - was assessed to evaluate how skin represents internal Hg and Se distribution for monitoring purposes. Mercury in skin had a concentration range of 0.68-3.11μgg-1 dry weight (DW), while Se had a higher concentration range of 74.3-124.5μgg-1 DW. There was no significant correlation between selenium levels in any of the analyzed tissues. Thus, the skin selenium concentration did not reflect the tissular Se levels and did not provide information for biomonitoring. The lack of correlation is explained by the biological role of Se, provided that each tissue regulates Se levels according to physiological needs. However, the skin Hg level had significant positive correlation with the levels in internal tissues (ANOVA p<0.05), particularly with that of muscle (R2=0.79; ANOVA p=0.0008). Thus, this correlation permits the estimation of Hg content in muscle based on the multiplication of skin biopsy levels by a factor of 1.85. Mercury bioindication using skin biopsies is a non-lethal approach that allows screening of a large number of specimens with little disturbance and makes possible an adequate sampling strategy that produces statistically valid results in populations and study areas. The correlation between Hg levels in the skin and internal tissues supports the use of the epidermis of Commerson's dolphins for Hg biomonitoring in the waters of the Subantarctic, which is a poorly studied region regarding Hg levels, sources and processes. © 2015 Elsevier Ltd.

Caceres-Saez I.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Ribeiro Guevara S.,Bariloche Atomic Center | Dellabianca N.A.,Museo Acatushun de Aves y Mamiferos Marinos Australes | Dellabianca N.A.,CONICET | And 4 more authors.
Environmental Monitoring and Assessment | Year: 2013

A survey of the elemental contents of K, Mg, Mn, Na, Cl, Br, Cs, Co, Rb, Fe, Zn, Al, Ti, V, As, Ag, Au and Cd in liver, kidney and muscle was performed in specimens of Commerson's dolphins (Cephalorhynchus c. commersonii) from subantarctic waters. The concentrations were determined by Instrumental Neutron Activation Analysis and the specimens derives from animals incidentally caught in artisanal fishing nets. Liver had the highest concentrations of Fe, 897(79) μg g-1 DW (dry weight) (average; standard deviation in parenthesis), kidney had the highest Cd, 35 (24) μg g-1 DW; Cl, 9,200 (1,700) μg g-1 DW; Na, 6,800 (1,100) μg g-1 DW and Br, 73(12) μg g-1 DW; and muscle the highest Mg 954 (71) μg g-1 DW. Potassium and Cs concentrations in muscle and kidney ranged in 12,510-13,020 and 0.230-0.252 μg g-1 DW, respectively; Zn and Mn concentrations were similar in liver and kidney (117-122.1 and 3.66-16.5 μg g-1 DW, respectively). Silver was high in liver 5.4(5.0) μg g-1 DW and kidney 1.2(2.7) μg g-1 DW. Gold, Rb, Co and As had no differences among tissues. Likewise, as in other odontocete species, the concentrations of essential elements showed little variation between the specimens analyzed, since they are regulated biochemically; however, heavy metals showed high variability. This study constitutes the first large description of the elemental composition in Commerson's dolphins from subantarctic waters of the South Atlantic Ocean. © 2012 Springer Science+Business Media Dordrecht.

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