“Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean” supplementary material and data

	1	Journal name: Paleobiology
	2	Title: Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean
	3	Dataset: Figures and data related to the study of archaeological and modern bone and shell samples from South-Western Atlantic Ocean.
	4	Authors: Maria Bas*. Department of Evolutionary Biology, Ecology and Environmental Sciences, Biodiversity Research Institute (IrBIO), University of Barcelona, Avinguda Diagonal 643, 08028 Barcelona, Spain. *Present address: Renewable Marine Resources Department, Institute 		of Marine Sciences (ICM-CSIC), Passeig Marítim de la Barceloneta, n°37-49, 08003, Barcelona, Spain. E-mail: mbaslpez@gmail.com
		Angélica M. Tivoli and Fernando Santiago. Centro Austral de Investigaciones Científicas – CONICET, Bernardo Houssay 200, 9410 Ushuaia, Argentina. E-mail: amtivoli@gmail.com, ersant2@gmail.com
		Ivan Briz i Godino. Equip de Recerca Arqueològica i Arqueomètrica de la Universitat de Barcelona (ERAAUB), Institut d’Arqueologia de la Universitat de Barcelona (IAUB), University of Barcelona, Montalegre 6-8, 08001 Barcelona, Spain; Centro Austral de Investigaciones 		Científicas – CONICET, Bernardo Houssay 200, 9410 Ushuaia, Argentina and Department of Archaeology, University of York, King's Manor, YO1 7EP York, UK. E-mail: ibrizgodino@gmail.com
		Mónica Salemme. Centro Austral de Investigaciones Científicas – CONICET, Bernardo Houssay 200, 9410 Ushuaia, Argentina and ICSE, Universidad Nacional de Tierra del Fuego, Fuegia Basket 251, 9410 Ushuaia, Argentina. E-mail: monica.salemme@gmail.com
		Juan Bautista Belardi. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos (ICASUR)-CIT Santa Cruz (CONICET), Avenida Lisandro de la Torre 860, 9400 Santa Cruz, Argentina. E-mail: juanbautistabelardi@gmail.com
		Florencia Borella. CONICET- INCUAPA, UNCPBA, Avenida Del Valle 5737, B7400JWI Olavarría, Argentina. E-mail: florborella@gmail.com
		Damián G. Vales and Enrique A. Crespo. Center for the Study of Marine Systems (CESIMAR, CONICET), Boulevard Brown 2915, U9120ACD Puerto Madryn, Argentina. E-mail: vales@cenpat-conicet.gob.ar; kike@cenpat-conicet.gob.ar
		Luis Cardona. Department of Evolutionary Biology, Ecology and Environmental Sciences, Biodiversity Research Institute (IrBIO), University of Barcelona, Avinguda Diagonal 643, 08028 Barcelona, Spain. E-mail: luis.cardona@ub.edu
	12	Abstract: This study compares the δ15N values and the trophic position of two seabird species throughout the Late Holocene in three regions in the South-Western Atlantic Ocean to assess the hypothesis that the decimation of megafauna lead to changes in the trophic position of 		mesopredators. Modern and ancient mollusc shells were also analysed to account for changes in the isotopic baseline through time. Results revealed that modern Magellanic penguins have higher δ15N values than their ancient conspecifics in the three regions, after controlling for 		changes in the isotopic baseline. This was also true for modern Imperial shags compared to ancient unidentified cormorants/shags from the two areas where ancient specimens were recovered (Southern Patagonia and the Beagle Channel). Such temporal variability might be caused by 		three non-mutually exclusive processes: decreased availability of pelagic squat lobster resulting from decreasing primary productivity through the Late Holocene, increased availability of small fishes resulting from the sequential depletion of other piscivores (South American fur seal 		and 	sea lion and Argentine hake) since the late 18th century and modification of the migratory patterns of Magellanic penguins. Although disentangling the relative contribution of all those processes is impossible at this time, the results reported here demonstrate that the ecology of 		Magellanic penguins and Imperial shags has undergone major changes since the Late Holocene.
	13	Research domain: Biological sciences.
	14	Contact person for questions: Dr. Maria Bas (mbaslpez@gmail.com)
	15	Date of data collection: 2010-2018.
	16	Information about geographic location of data collection: Argentina
	17	Keywords: Imperial shag; Magellanic penguin; Marine ecosystem; stable isotopes; zooarchaeology.
	18	Language information: English (some locations in Spanish).
	19	Information about funding sources: Fundació Bosch i Gimpera

Here you have the description of the supplementary material:

FIGURE S1: Boxplots for stable isotope ratios of N and C for each region with archaeological and modern mollusc samples. Related to “Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean”.

TABLE S1: Archaeological sites where shells and vertebrate bones were recovered from Northern Patagonia, Southern Patagonia and the Beagle Channel (Tierra del Fuego) studied in “Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean”.

TABLE S2: Raw data of stable isotope values of δ13C (‰), δ15N (‰) and C:N atomic ratios of each bone sample (fish and seabirds) of the present and archaeological sites studied in “Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean”.

TABLE S3: Raw data of stable isotope values of δ13C (‰) and δ15N (‰) of each individual specimen (mollusc shells) of the present and archaeological sites studied in “Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean”.

All the methodology can be found at material and methods section in “Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the South-Western Atlantic Ocean”.