Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-27T06:35:59.623Z Has data issue: false hasContentIssue false
  • English
  • Français

Shifting niches of marine predators due to human exploitation: the diet of the South American sea lion (Otaria flavescens) since the late Holocene as a case study

Published online by Cambridge University Press:  27 April 2015

Lisette Zenteno ,
Florencia Borella ,
Julieta Gómez Otero ,
Ernesto Piana ,
Juan Bautista Belardi ,
Luis Alberto Borrero ,
Fabiana Saporiti ,
Luis Cardona  and
Enrique Crespo
Lisette Zenteno
Affiliation:
Department of Animal Biology, Faculty of Biology, University of Barcelona, Avenida Diagonal, 643 (08028) Barcelona, Spain. E-mail: lisette.zenteno@gmail.com
Florencia Borella
Affiliation:
Faculty of Social Sciences, National University of Central Buenos Aires, (INCUAPA – CONICET), Avenida Del Valle 5737, Argentina. E-mail: fborella@soc.unicen.edu.ar
Julieta Gómez Otero
Affiliation:
Laboratory of Marine Mammals, Centro Nacional Patagónico (CENPAT-CONICET), National University of Patagonia, Brown, 3600 (9120) Puerto Madryn, Argentina. E-mail: julietagomezotero@yahoo.com.ar
Ernesto Piana
Affiliation:
Proyecto Arqueológico Canal Beagle, Centro Austral de Investigaciones Científicas (CADIC –CONICET), Houssay 200 (9410), Ushuaia, Argentina. E-mail: arqueologiatierradelfuego@gmail.com
Juan Bautista Belardi
Affiliation:
Unidad Académica Río Gallegos, Universidad Nacional de la Patagonia Austral (CONICET), Campus Universitario, Avenida Gregores y Piloto Rivera s/n (CP 9400), Santa Cruz, Argentina. E-mail: juanbautistabelardi@gmail.com
Luis Alberto Borrero
Affiliation:
Instituto Multidisciplinario de Historia y Ciencias Humanas (IMHICIHU-CONICET), Saavedra 15, Piso 5 (1083 ACA) Buenos Aires, Argentina. E-mail: laborrero2003@yahoo.com
Fabiana Saporiti
Affiliation:
Department of Animal Biology, Faculty of Biology, University of Barcelona, Avenida Diagonal, 643 (08028) Barcelona, Spain. E-mail: lisette.zenteno@gmail.com
Luis Cardona
Affiliation:
Department of Animal Biology, Faculty of Biology, University of Barcelona, Avenida Diagonal, 643 (08028) Barcelona, Spain. E-mail: lisette.zenteno@gmail.com
Enrique Crespo
Affiliation:
Laboratory of Marine Mammals, Centro Nacional Patagónico (CENPAT-CONICET), National University of Patagonia, Brown, 3600 (9120) Puerto Madryn, Argentina. E-mail: julietagomezotero@yahoo.com.ar
Get access Rights & Permissions [Opens in a new window]

Abstract

—Stable isotope ratios of carbon and nitrogen in archaeological and modern bone samples have been used to reconstruct the dietary changes of the South American sea lion Otaria flavescens from the late Holocene to the present in the southwestern Atlantic. We sampled bones from archaeological sites in northern-central and southern Patagonia, Argentina, and bones housed in modern scientific collections. Additionally, we analyzed the stable isotope ratios in ancient and modern shells of intertidal molluscs to explore changes in the isotope baseline and allow comparison between bone samples from different periods after correction for baseline shifts. Results confirmed the trophic plasticity of the South American sea lion, demonstrated the much larger impact of modern exploitation of marine resources as compared with that of hunter-gatherers, and underscored the dissimilarity between the past and modern niches of exploited species. These conclusions are supported by the rather stable diet of South American sea lions during several millennia of aboriginal exploitation, in both northern-central and southern Patagonia, and the dramatic increase in trophic level observed during the twentieth century. The recent increase in trophic level might be related to the smaller population size resulting from modern sealing and the resulting reduced intraspecific competition. These results demonstrate how much can be learned about the ecology of modern species thanks to retrospective studies beyond the current, anthropogenically modified setting where ecosystem structure is totally different from that in the pristine environments where current species evolved.

Type
Articles
Information
Paleobiology , Volume 41 , Supplement 3 , June 2015 , pp. 387 - 401
Copyright
Copyright © 2015 The Paleontological Society. All rights reserved. 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

Ambrose, S. H., and DeNiro, M. J.. 1989. Climate and habitat reconstruction using stable carbon and nitrogen isotope ratios of collagen in prehistoric herbivore teeth from Kenya. Quaternary Research 31:401–422.CrossRefGoogle Scholar
Antonelis, G. A., Stewart, B. S., and Perryman, W. F.. 1990. Foraging characteristics of female northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus). Canadian Journal of Zoology 68:150–158.CrossRefGoogle Scholar
Bailey, G., Barrett, J., Craig, O., and Milner, N.. 2008. Historical ecology of the North Sea Basin: an archaeological perspective and some problems of methodology. Pp. 215–242in T. C. Rick, and J. M. Erlandson, eds. Human impacts on ancient marine ecosystems: a global perspective. University of California Press, Berkeley.Google Scholar
Balasse, M., Bocherens, H., and Mariotti, A.. 1999. Intra-bone variability of collagen and apatite isotopic composition used as evidence of a change of diet. Journal of Archaeological Science 26:593–598.CrossRefGoogle Scholar
Belardi, J. B., Carballo Marina, F., and L’Heureux, G.. 2011. Nuevos resultados arqueológicos en Cabo Vírgenes (Santa Cruz, Argentina): el sitio Cabo Vírgenes 20. Magallania (Chile) 39:279–292.Google Scholar
Blaauw, M. 2010. Methods and code for ‘classical’ age-modelling of radiocarbon sequences. Quaternary Geochronology 5:512–518.CrossRefGoogle Scholar
Bligh, E. G., and Dyer, W. J.. 1959. A rapid method of total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology 37:911–917.CrossRefGoogle ScholarPubMed
Borella, F., and Cruz, I.. 2012. Taphonomic evaluation of penguin (Spheniscidae) remains at a shell-midden on the northern coast of Patagonia (San Matías Gulf, Río Negro, Argentina). Quaternary International 278:45–50.CrossRefGoogle Scholar
Braje, T. J., and Rick, T. C.. 2011. Human impacts on seals, sea lions, and sea otters: integrating archaeology and ecology in the Northeast Pacific. University of California Press, Berkeley.CrossRefGoogle Scholar
Bridges, L. 1949. Uttermost part of the Earth: Indians of Tierra del Fuego. Dover, New York.Google Scholar
Bullock, J. M., Aronson, J., Newton, A. C., Pywell, R. F., and Rey-Benayas, J. M.. 2011. Restoration of ecosystem services and biodiversity: conflicts and opportunities. Trends in Ecology and Evolution 26:541–549.CrossRefGoogle ScholarPubMed
Bunn, S. E., Loneragan, N. R., and Kempster, M. A.. 1995. Effects of acid washing on stable isotope ratios of C and N in penaeid shrimp and seagrass: implications for food-web studies using multiple stable isotopes. Limnology and Oceanography 40:622–625.CrossRefGoogle Scholar
Campagna, C., Werner, R., Karesh, W., Marin, M. R., Koontz, F., Cook, R., and Koontz, C.. 2001. Movements and location at sea of South American sea lions (Otaria flavescens). Journal of Zoology 257:205–220.CrossRefGoogle Scholar
Cappozzo, H. L., and Perrin, W. F.. 2009. South American sea lion Otaria flavescens. Pp. 1076–1079in W. F. Perrin, B. Würsig, and J. G. M. Thewissen, eds. Encyclopedia of marine mammals, 2nd ed.Elsevier, Amsterdam.CrossRefGoogle Scholar
Casey, M., and Post, D.. 2011. The problem of isotopic baseline: reconstructing the diet and trophic position of fossil animals. Earth-Science Reviews 106:131–148.CrossRefGoogle Scholar
Cherel, Y., Kernaleguen, L., Richard, P., and Guinet, C.. 2009. Whisker isotopic signature depicts migration patterns and multi-year intra- and inter-individual foraging strategies in fur seals. Biology Letters 5:830–832.CrossRefGoogle ScholarPubMed
Ciancio, J. E., Pascual, M. A., Botto, F., Frere, E., and Iribarne, O.. 2008. Trophic relationships of exotic anadromous salmonids in the Southern Patagonian Shelf as inferred from stable isotopes. Limnology and Oceanography 53:788–798.CrossRefGoogle Scholar
Clementz, M. T., and Koch, P. L.. 2001. Differentiating aquatic mammal habitat and foraging ecology with stable isotopes in tooth enamel. Oecologia 129:461–472.CrossRefGoogle ScholarPubMed
Cordero, R. R., Panarello, H., Lanzelotti, S., and Favier Dubois, C. M.. 2003. Radiocarbon age offsets between living organisms from the marine and continental reservoir in coastal localities of Patagonia (Argentina). Radiocarbon 45:9–15.CrossRefGoogle Scholar
Crenshaw, M. A. 1980. Mechanisms of shell formation and dissolution. Pp. 115–132in D. Rhoads and R. Lutz, eds. Skeletal growth of aquatic organisms. Plenum, New York.CrossRefGoogle Scholar
Crespo, E. A., and Pedraza, S. N.. 1991. Estado actual y tendencia de la población de lobos marinos de un pelo (Otaria flavescens) en el litoral norpatagónico. Austral Ecology 1:87–95.Google Scholar
Crutzen, P. J.. 2002. Geology of mankind. Nature 415:23.CrossRefGoogle ScholarPubMed
Dans, S. L., Crespo, E. A., Pedraza, S. N., and Koen-Alonso, M.. 2004. Recovery of the South American sea lion population (Otaria flavescens) in northern Patagonia. Canadian Journal of Fisheries and Aquatic Sciences 61:1681–1690.CrossRefGoogle Scholar
Dato, C., Bambill, G., Cañete, G., Villarino, M. L., and Aubone, A.. 2006. Estimación cuantitativa del descarte en la pesquería de merluza realizado por la flota comercial argentina. Mar del Plata. INIDEP 6:31–38.Google Scholar
Dickinson, A. B. 2007. Seal fisheries of the Falkland Islands and dependences: an historical overview. International Maritime Economic History Association, St. John’s, Newfoundland.CrossRefGoogle Scholar
Drago, M., Crespo, E. A., Aguilar, A., Cardona, L., García, N., Dans, S. L., and Goodall, N. 2009. Historic diet change of the South American sea lion in Patagonia as revealed by isotopic analysis. Marine Ecology Progress Series 384:273–289.CrossRefGoogle Scholar
Drago, M., Cardona, L., Crespo, E. A., Grandi, M. F., and Aguilar, A. 2010. Reduction of skull size in South American sea lions reveals density-dependent growth during population recovery. Marine Ecology Progress Series 420:253–261.CrossRefGoogle Scholar
Favier Dubois, C. M. 2009. Valores de efecto reservorio marino para los últimos 5.000 años obtenidos en concheros de la costa atlántica norpatagónica (Golfo San Matías, Argentina). Magallania 37:139–147.CrossRefGoogle Scholar
Favier Dubois, C. M., and Kokot, R. 2011. Changing scenarios in Bajo de la Quinta (San Matías Gulf, Northern Patagonia, Argentina): impact of geomorphologic processes in subsistence and human use of coastal habitats. Quaternary International 245:103–110.CrossRefGoogle Scholar
Favier Dubois, C. M., and Scartascini, F. 2012. Intensive fishery scenarios on the North Patagonian coast (Río Negro, Argentina) during the Mid-Holocene. Quaternary International 256:62–70.CrossRefGoogle Scholar
Favier Dubois, C. M., Borella, F., and Tykot, R. H. 2009. Explorando tendencias en el uso humano del espacio y los recursos en el litoral rionegrino durante el Holoceno tardío y medio. Pp. 985–997in M. Salemme, F. Santiago, M. Álvarez, E. Piana, M. Vázquez, and E. Mansur, eds. Arqueología de Patagonia: una mirada desde el último confín. Utopías, Ushuaia, Argentina.Google Scholar
Franco-Trecu, V., Aurioles-Gamboa, D., Arim, M., and Lima, M. 2012. Prepartum and postpartumtrophic segregation between sympatrically breeding female Arctocephalus australis and Otaria byronia. Journal of Mammalogy 93:514–521.CrossRefGoogle Scholar
Gannes, L. Z., Obrien, D. M., and Martínez del Rio, C. 1997. Stable isotopes in animal ecology: assumptions, caveats, and a call for more laboratory experiments. Ecology 78:1271–1276.CrossRefGoogle Scholar
Gentry, R. L. 2009. Eared seals Otariidae. Pp. 339–342in W. F. Perrin, B. Würsig, and J. G. M. Thewissen, eds. Encyclopedia of marine mammals, 2nd ed.Elsevier, Amsterdam.CrossRefGoogle Scholar
Gómez Otero, J. 2006. Dieta, uso del espacio y evolución en sociedades cazadoras recolectoras de la costa centro-septentrional de Patagonia durante el Holoceno medio y tardío. Ph.D. thesis. Universidad de Buenos Aires, Buenos Aires.Google Scholar
Gómez Otero, J., Weiler, N., Banegas, A., and Moreno, E. 2013. Ocupaciones del Holoceno medio en Bahía Cracker, costa atlántica de Patagonia central. Pp. 177–186in A. Zangrando, R. Barberena, A. Gil, G. Neme, M. Giardina, L. Luna, C. Otaola, S. Paulides, L. Salgán, and A. Tívoli Tendencias teórico-metodológicas y casos de estudio en la arqueología de la Patagonia. Museo de Historia Natural de San Rafael, San Rafael, Argentina.Google Scholar
Grandi, M. F., Oliveira, L. R., Dans, S. L., and Crespo, E. A. 2012. A hunted population in recovery: effective population size for South American sea lions from Patagonia. Animal Biology 62:433–450.CrossRefGoogle Scholar
Halpern, B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V., Micheli, F., D’Agrosa, C., Bruno, J. F., Casey, K. S., Ebert, C., Fox, H. E., Fujita, R., Heinemann, D., Lenihan, H. S, Madin, E. M. P., Perry, M. T., Selig, E. R., Spalding, M., Steneck, R., and Watson, R. 2008. A global map of human impact on marine ecosystems. Science 319:948–952.CrossRefGoogle ScholarPubMed
Hirons, A. C., Schell, D. M., and St. Aubin, D. J. 2001. Growth rates of vibrissae of harbor seals (Phoca vitulina) and Steller sea lions (Eumetobias jubatus). Canadian Journal of Zoology 79:1053–1061.CrossRefGoogle Scholar
Hobson, K. A. 1999. Tracing origins and migration of wildlife using stable isotopes: a review. Oecologia 120:314–326.CrossRefGoogle ScholarPubMed
Hobson, K. A., Schell, D. M., Renouf, D., and Noseworthy, E. 1996. Stable carbon and nitrogen isotopic fractionation between diet and tissues of captive seals: implications for dietary reconstructions involving marine mammals. Canadian Journal of Fisheries and Aquatic Sciences 53:528–533.CrossRefGoogle Scholar
Hogg, A. G., Hua, Q., Blackwell, P. G., Niu, M., Buck, C. E., Guilderson, T. P., Heaton, T. J., Palmer, J. G., Reimer, P. J., Reimer, R. W., Turney, C. S. M., and Zimmerman, S. R. H. 2013. SHcal13 Southern Hemisphere calibration, 0–50,000 years cal BP. Radiocarbon 55:1889–1903.CrossRefGoogle Scholar
Jackson, S. T, and Hobbs, R. J. 2009. Ecological restoration in the light of ecological history. Science 325:567–569.CrossRefGoogle ScholarPubMed
Jackson, J. B. C., Kirby, M. X., Berger, W. H., Bjorndal, K. A., Botsford, L. W., Bourque, B. J., Bradbury, R., Cooke, R., Erlandson, J., Estes, J. A., Hughes, T. P., Kidwell, S., Lange, C. B., Lenihan, H. S., Pandolfi, J. M., Peterson, C. H., Steneck, R. S., Tegner, M. J., and Warner, R. 2001. Historical overfishing and the recent collapse of coastal ecosystems. Science 293:629–638.CrossRefGoogle ScholarPubMed
Jones, T. L., Hildebrant, W. R., Kennett, D. J., and Porcasi, J. F. 2004. Prehistoric marine mammal overkill in the northeastern Pacific: a review of new evidence. Journal of California and Great Basin Anthropology 24:69–80.Google Scholar
Koch, P. L. 2007. Isotopic study of the biology of modern and fossil vertebrates. Pp. 99–154in R. Michener and K. Lajtha, eds. Stable isotopes in ecology and environmental science. Blackwell, Malden, Mass.CrossRefGoogle Scholar
Koen-Alonso, M., and Yodzis, P. 2005. Multispecies modelling of some components of the northern and central Patagonia marine community, Argentina. Canadian Journal of Fisheries and Aquatic Sciences 62:1490–1512.CrossRefGoogle Scholar
Koen Alonso, M., Crespo, E. A., Pedraza, S. N., Garcia, N. A., and Coscarella, M. A. 2000. Food habits of the South American sea lion, Otaria flavescens, off Patagonia, Argentina. Fishery Bulletin 98:250–263.Google Scholar
Kovacs, K. M., Aguilar, A., Aurioles, D., Burkanov, V., Campagna, C., Gales, N., Gelatt, T., Goldsworthy, S. D., Goodman, S. J., Hofmeyr, G. J. G., Härkönen, T., Lowry, L, Lydersen, C., Schipper, J., Sipilä, J. T., Southwell, C., Stuart, S., Thompson, D., and Trillmich, F. 2012. Global threats to pinnipeds. Marine Mammal Science 28:414–436.CrossRefGoogle Scholar
L’Heureux, G. L., and Franco, N. V. 2002. Ocupaciones humanas en el área de Cabo Vírgenes (Pcia. de Santa Cruz, Argentina): el sitio Cabo Vírgenes 6. Anales Instituto Patagonia, serie Ciencias Humanas 30:183–201.Google Scholar
Lorrain, A. 2003. Decarbonation and preservation method for the analysis of organic C and N contents and stable isotope ratios of low-carbonated suspended particulate material. Analytica Chimica Acta 491:125–133.CrossRefGoogle Scholar
Martin, P. S. 2005. Twilight of the mammoths. University of California Press, Berkeley.CrossRefGoogle Scholar
Martínez del Rio, C., Wolf, N., Carleton, S. A., and Gannes, L. Z. 2009. Isotopic ecology ten years after a call for more laboratory experiments. Biological Reviews 4:91–111.CrossRefGoogle Scholar
Nardoto, G. B., Godoy, P. B., Ferraz, E. S. B., Ometto, J. P. H. B., and Martinelli, L. A. 2006. Stable carbon and nitrogen isotopic fractionation between diet and swine tissues. Scientia Agricola 63:579–582.CrossRefGoogle Scholar
Newsome, S. D., Koch, P. L., Etnier, M. A., and Aurioles-Gamboa, D. 2006. Using carbon and nitrogen isotope values to investigate maternal strategies in northeast Pacific otariids. Marine Mammal Science 22:556–572.CrossRefGoogle Scholar
Newsome, S. D., Etnier, M. A. C., Kurle, M., Waldbauer, J. R., Chamberlain, C. P., and Koch, P. L. 2007). The shifting baseline of northern fur seal ecology in the northeast Pacific Ocean. Proceedings of the National Academy of Sciences USA 104:9709–9714.CrossRefGoogle Scholar
Newsome, S. D., Bentall, G. B., Tinker, M. T., Oftedal, O. T., Ralls, K., Estes, J., and Fogel, M. 2010. Variation in δ13C and δ15N diet-vibrissae trophic discrimination factors in a wild population of California sea otters. Ecological Applications 20:1744–1752.CrossRefGoogle Scholar
Olive, P. J. W., Pinnegar, J. K., Polunin, N. V. C., Richards, G., and Welch, R. 2003. Isotope trophic-step fractionation: a dynamic equilibrium model. Journal of Animal Ecology 72:608–617.CrossRefGoogle ScholarPubMed
Orquera, L. A., and Piana, L. E. 1988. Human littoral adaptation in the Beagle Channel region: the maximum possible age. Quaternary of South America and Antarctic Peninsula 5:133–165.Google Scholar
Orquera, L. A., and Piana, L. E. 1999. Arqueología de la región del canal Beagle (Tierra del Fuego, República Argentina). Sociedad Argentina de Antropología, Buenos Aires.Google Scholar
Orquera, L., Legoupil, A. D., and Piana, L. E. 2011. Littoral adaptation at the southern end of South America. Quaternary International 239:61–69.CrossRefGoogle Scholar
Páez, E. 2006. Situación de la administración del recurso lobos y leones marinos en Uruguay. Pp. 577–583in R. Menafra, L. Rodríguez-Gallego, F. Scarabino, and D. Conde, eds. Bases para la conservación y el manejo de la costa uruguaya. Vida Silvestre, Sociedad Uruguaya para la Conservación de la Naturaleza, Montevideo.Google Scholar
Páez-Rosas, D., Aurioles-Gamboa, D., Alava, J. J., and Palacios, D. M. 2012. Stable isotopes indicate differing foraging strategies in two sympatric otariids of the Galapagos Islands. Journal of Experimental Marine Biology and Ecology 424–425:44–52.CrossRefGoogle Scholar
Passey, B. H., and Cerling, T. E. 2002. Tooth enamel mineralization in ungulates: implications for recovering a primary isotopic time-series. Geochimica et Cosmochimica Acta 66:322–3234.CrossRefGoogle Scholar
Piana, E., Vila, A., Orquera, L., and Estévez, J. 1992. Chronicles of ‘Ona-Ashaga’: archaeology in the Beagle Channel (Tierra del Fuego-Argentina). Antiquity 66:771–783.CrossRefGoogle Scholar
Piana, E. L., Vázquez, M., and Cerraso, A. 2007. Kaiyawoteha. Informe de excavación. Informe Técnico para la Dirección de Ciencia y Tecnología de Tierra del Fuego, Ushuaia.Google Scholar
Porcasi, J. F., Jones, T. L., and Raab, L. M. 2000. Trans-Holocene marine mammal exploitation on San Clemente Island, California: a tragedy of the commons revisited. Journal of Anthropological Archaeology 19:200–220.CrossRefGoogle Scholar
Riet-Sapriza, F. G., Costa, D. P., Franco-Trecu, V., Marín, Y., Chocca, J., González, B., Beathyate, G., Chilvers, L., and Hückstädt, L. A. 2012. Foraging behavior of lactating South American sea lions (Otaria flavescens) and spatial-temporal resource overlap with the Uruguayan fisheries. Deep Sea Research II: Topical Studies in Oceanography 88:106–119.Google Scholar
Riofrío-Lazo, M., and Aurioles Gamboa, D. 2013. Timing of isotopic integration in marine mammal skull: comparative study between calcified tissues. Rapid Communications in Mass Spectrometry 27:1076–1082.CrossRefGoogle ScholarPubMed
Rodriguez, D., and Bastida, R. 1998. Four hundred years in the history of pinniped colonies around Mar del Plata, Argentina. Aquatic Conservation: Marine and Freshwater Ecosystems 8:721–735.3.0.CO;2-L>CrossRefGoogle Scholar
Romero, M. A., Dans, S., Gonzalez, R., Svendsen, G., Garcia, N., and Crespo, E. A. 2011. Solapamiento trofico entre el lobo marino de un pelo Otaria flavescens y la pesqueria de arrastre demersal del golfo. San Matias, Patagonia, Argentina: Latin American Journal of Aquatic Research 39:344–358.Google Scholar
Schiavini, A. 1993. Los lobos marinos como recurso para cazadores-recolectores marinos: el caso de Tierra del Fuego. Latin American Antiquity 4:346–366.CrossRefGoogle Scholar
Schiavini, A. C. M., Crespo, E. A., and Szapkievich, V. 2004. Status of the population of South American sea lion (Otaria flavescens, Shaw, 1800) in southern Argentina. Mammalian Biology 69:108–118.CrossRefGoogle Scholar
Schwarcz, H. P. 2000. Some biochemical aspects of carbon isotopic paleodiet studies. Pp. 189–209in S. H. Ambrose and M. A. Katzenberg, eds. Biogeochemical approaches to paleodietary analysis. Kluwer Academic/Plenum, New York.Google Scholar
Serrán, M. N. D., Centeno, N., Weiler, N., and Gómez Otero, J. 2008. Massive death of pinnipeds 1200 years ago: taphonomic history of the “Lobos site” (Golfo Nuevo, Patagonia, Argentina). Quaternary International 183:135–142.CrossRefGoogle Scholar
Steadman, D. W. 2006. Extinction and biogeography of tropical Pacific birds. University of Chicago Press, Chicago.Google Scholar
Suárez, A. A., Sanfelice, D., Cassini, M. H., and Cappozzo, H. L. 2005. Composition and seasonal variation in the diet of the South American sea lion (Otaria flavescens) from Quequén, Argentina. Latin American Journal of Aquatic Science 4:163–174.Google Scholar
Terborgh, J., and Estes, J. A. 2010. Trophic cascades: predators, prey, and the changing dynamics of nature. Island Press, Washington, D.C.Google Scholar
Thompson, D., Duck, C. D., McConnell, B. J., and Garrett, J. 1998. Foraging behaviour and diet of lactating female southern sea lions (Otaria flavescens) in the Falkland Islands. Journal of Zoology 246:135–146.CrossRefGoogle Scholar
Thompson, D., Strange, I., Riddy, M., and Duck, C. D. 2005. The size and status of the population of southern sea lions Otaria flavescens in the Falkland Islands. Biological Conservation 121:357–367.CrossRefGoogle Scholar
Tivoli, A. M., and Zangrando, A. F. 2011. Subsistence variations and landscape use among maritime hunter-gatherers. A zooarchaeological analysis from the Beagle Channel (Tierra del Fuego, Argentina). Journal of Archaeological Science 38:1148–1156.CrossRefGoogle Scholar
Yodzis, P. 1998. Local trophodynamics and the interaction of marine mammals and fisheries in the Benguela ecosystem. Journal of Animal Ecology 67:635–658.CrossRefGoogle Scholar
Zar, J. H. 1984. Biostatistical analysis. 2nd ed. Prentice-Hall, Englewood Cliffs, N.J.Google Scholar