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

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• 作者：Damián G. Vales ; Luis Cardona ; Atilio F. Zangrando ; Florencia Borella…
• 关键词：Fur seals ; Arctocephalus australis ; Historical ecology ; Hunter ; gatherers ; Sealing ; Environmental changes ; Stable isotopes
• 刊名：Oecologia
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：183
• 期：2
• 页码：555-570
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Ecology; Plant Sciences; Hydrology/Water Resources;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1939
• 卷排序：183

文摘

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: δ13C_2200-0BP = −13.4 ± 0.5‰, δ15N_2200-0BP = 20.6 ± 1.1‰). Conversely, Middle Holocene fur seals fed more pelagically than their modern conspecifics in the Río de la Plata region (δ13C_7000BP = −15.9 ± 0.6‰ vs. δ13C_PRESENT = −13.5 ± 0.8‰) and Tierra del Fuego (δ13C_6400-4300BP = −15.4 ± 0.5‰ vs. δ13C_PRESENT = −13.2 ± 0.7‰). In the latter region, Middle Holocene fur seals also fed at a higher trophic level than their modern counterparts (δ15N_6400-4300BP = 20.5 ± 0.5‰ vs. δ15N_PRESENT = 19.0 ± 1.6‰). Nevertheless, a major dietary shift was observed in fur seals from Tierra del Fuego during the nineteenth century (δ13C_100BP = −17.2 ± 0.3‰, δ15N_100BP = 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.