Using combined biomolecular methods to explore whale exploitation and social aggregation in hunter–gatherer–fisher society in Tierra del Fuego

Cetaceans were an important food and raw material resource for the South American hunter–gatherer–fisher (HGF) communities of Tierra del Fuego. Historic ethnographic evidence suggests that relatively mobile HGF groups came together in large numbers to exploit carcasses from individual cetacean stranding events. Substantial accumulations of whale bones within shell middens in the Lanashuaia locality of the Beagle Channel suggests that these social aggregation events may also have occurred in pre-historic periods. The difficulty in assigning taxonomic identifications to the fragmentary whale remains, however, made it difficult to explicitly test this hypothesis. Here, we applied two different biomolecular techniques, collagen peptide mass fingerprinting (ZooMS) and ancient mitochondrial DNA analysis to 42 archeological bone fragments from the Lanashuaia locality to provide accurate species identifications. There was a clear correspondence between ZooMS and DNA results, identifying five different cetacean species (Southern bottlenose, blue, humpback, right, and sei whale) as well as human and sea lion remains. The biomolecular results were not conclusively consistent with HGF social aggregation, revealing an unexpectedly diverse range of cetaceans within the Lanashuaia middens. However, the results could not fully refute the hypothesis that cetacean remains can be used as anthropic markers of aggregation events, as the observed species and haplotypes revealed potential shared exploitation of some whale resources between midden sites

Gastrointestinal helminths of commerson's dolphins Cephalorhynchus Commersonii from central Patagonia and Tierra del Fuego

The stomachs and intestines of 9 Commerson's dolphins incidentally caught in trawl nets in central Patagonia and 23 stranded on beaches in Tierra del Fuego were surveyed for helminth parasites. A total of 267 individuals belonging to 4 species of parasites (1 nematode, 3 digeneans) were found in the dolphins from the first area: Anisakis sp. (larvae type 1 = A. simplex), Braunina cordiformis, Hadwenius sp. and Pholeter gastrophilus. In the Tierra del Fuego dolphins, 142 specimens belonging to 3 species (2 nematodes, 1 digenean, 1 cestode) were found: A. simplex, Hadwenius sp. and Strobilocephalus triangularis. Only 2 of the helminth species were shared in the 2 study areas, A. simplex and Hadwenius sp., and both were more common in central Patagonia. Among the species, A. simplex was most prevalent and abundant in both study areas. In Tierra del Fuego, adults of A. simplex appeared in only 1 host. Hadwenius sp., P. gastrophilus and S. triangularis are new host records for Commerson's dolphin. Species diversity and species richness were low in both study areas. Helminth communities were more diverse in central Patagonia (t = 1.97, df = 258, p < 0.05) and species richness was higher in central Patagonia (S = 4). No differences in diversity were observed between females and males of central Patagonia (t = 1.97, df = 139, p < 0.05) and between females of central Patagonia and Tierra del Fuego. The results may suggest some differences in habitat use, diet and sex between Commerson's dolphin populations in the 2 study areas.Fil: Berón-Vera, Bábara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Pedraza, Susana Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Raga, Juan Antonio. Universidad de Valencia; EspañaFil: Gil de Pertierra, Alicia Alida. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Koen Alonso, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Prosser Goodall, Rae Natalie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Holocene changes in the trophic ecology of an apex marine predator in the South Atlantic Ocean

Predators may modify their diets as a result of both anthropogenic and natural environmental changes. Stable isotope ratios of nitrogen and carbon in bone collagen have been used to reconstruct the foraging ecology of South American fur seals (Arctocephalus australis) in the southwestern South Atlantic Ocean since the Middle Holocene, a region inhabited by hunter-gatherers by millennia and modified by two centuries of whaling, sealing and fishing. Results suggest that the isotopic niche of fur seals from Patagonia has not changed over the last two millennia (average for the period: δ13C2200-0BP = −13.4 ± 0.5‰, δ15N2200-0BP = 20.6 ± 1.1‰). Conversely, Middle Holocene fur seals fed more pelagically than their modern conspecifics in the Río de la Plata region (δ13C7000BP = −15.9 ± 0.6‰ vs. δ13CPRESENT = −13.5 ± 0.8‰) and Tierra del Fuego (δ13C6400-4300BP = −15.4 ± 0.5‰ vs. δ13CPRESENT = −13.2 ± 0.7‰). In the latter region, Middle Holocene fur seals also fed at a higher trophic level than their modern counterparts (δ15N6400-4300BP = 20.5 ± 0.5‰ vs. δ15NPRESENT = 19.0 ± 1.6‰). Nevertheless, a major dietary shift was observed in fur seals from Tierra del Fuego during the nineteenth century (δ13C100BP = −17.2 ± 0.3‰, δ15N100BP = 18.6 ± 0.7‰), when marine primary productivity plummeted and the fur seal population was decimated by sealing. Disentangling the relative roles of natural and anthropogenic factors in explaining this dietary shift is difficult, but certainly the trophic position of fur seals has changed through the Holocene in some South Atlantic regions.Fil: Vales, Damián Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Cardona, Luis. Universidad de Barcelona; EspañaFil: Zangrando, Atilio Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Borella, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; ArgentinaFil: Saporiti, Fabiana. Universidad de Barcelona; EspañaFil: Prosser Goodall, Rae Natalie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Museo Acatushún de Aves y Mamíferos Marinos Australes; ArgentinaFil: Rosa de Oliveira, Larissa. Universidade do Vale do Rio dos Sinos; Brasil. Study Group of Aquatic Mammals from Rio Grande do Sul ; BrasilFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia; Argentin

Stable isotopes of oxygen reveal dispersal patterns of the South American sea lion in the southwestern Atlantic Ocean

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.Fil: Zenteno, L.. Universidad de Barcelona; EspañaFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Prosser Goodall, Rae Natalie . Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Aguilar, A.. Universidad de Barcelona; EspañaFil: de Oliveira, L. . Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; BrasilFil: Drago, M.. Universidad de Barcelona; EspañaFil: Secchi, Eduardo Resende. Universidade Federal do Rio Grande do Sul; BrasilFil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Cardona, L.. Universidad de Barcelona; Españ

Status, population trend and genetic structure of South American fur seals, Arctocephalus australis , in southwestern Atlantic waters

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.Fil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia; ArgentinaFil: Schiavini, Adrian Carlos Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Franco Trecu, Valentina. Proyecto Pinnípedo; UruguayFil: Prosser Goodall, Rae Natalie. Museo Acatushún de Aves y Mamíferos; ArgentinaFil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Stenghel Morgante, João. Universidade de Sao Paulo; BrasilFil: Rosa de Oliveira, Larissa. Universidade do Vale do Rio dos Sinos; Brasil. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasi