Comparative analysis of the diet of Arctocephalus gazella (Pinnipedia), at two localities of the South Shetland Islands, with emphasis on the fish component

Descalzo, Mariana; Daneri, Gustavo Adolfo; Negrete, Javier; Corbalán, A.; Barrera-Oro, Esteban

doi:10.1590/1678-4766e2021024

Cited by 3 publications

(1 citation statement)

References 30 publications

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“…The total sh lengths estimated in this work showed that A. gazella preyed upon mature stages of P. antarctica and E. antarctica and immature stages of G. nicholsi and C. wilsoni. Similar sh ontogenetic stages were represented in the diets of fur seals from different colonies of the South Shetland Islands and the Antarctic Peninsula (Casaux et al 2003a(Casaux et al , 2003bOsman et al 2004;Descalzo et al 2021). P. antarctica inhabits pelagic waters over and near the bottom of the Antarctic continental shelf (Gon and Heemstra 1990; Pinkerton 2017).…”

Section: Resultsmentioning

confidence: 69%

The relevance of fish in the summer diet of the Antarctic fur seal (Arctocephalus gazella) at Hope Bay, Antarctic Peninsula and Stranger Point, South Shetland Islands

et al. 2023

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The sh incidence, particularly notothenioids and myctophids, in the diet of non-breeding male Arctocephalus gazella in the western Antarctic Peninsula (AP) region is scarcely known. We made a comparative diet analysis on 158 faecal samples collected in summer 2005 at Hope Bay (HB), AP and at Stranger Point (SP), South Shetland Islands (SSI). The occurrence of Antarctic krill Euphausia superba and sh as prey was similar at HB, whereas krill was predominant at SP. For each sh species identi ed based on the otoliths found, their relative importance in the diet was evaluated using the IRI index.Notothenioid sh prevailed at HB: Pleuragramma.antarctica was the most important prey followed by Chaenodraco wilsoni. Contrarily, myctophids predominated at SP: Gymnoscopelus nicholsiand Electrona antarctica were the dominant prey. Both benthopelagic and pelagic sh species were represented at HB, while the latter were more important at SP; we suggest that seals from SP are foraging in pelagic strata, while at HB their habitat includes benthic and pelagic environments. Demersal nototheniid species were scarcely represented and only at HB, which might be related to a preference of fur seals on the more abundant pelagic prey there. At SP, the absence of demersal nototheniid otoliths in the faeces could be linked to the historical n sh sheries that took place in the SSI area. On sh species consumption, there was a higher diversity at SP in comparison with HB but a low overlap between these sites. Our ndings are compared with studies from localities of the AP and the Scotia Arc.

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Section: Resultsmentioning

confidence: 69%

The relevance of fish in the summer diet of the Antarctic fur seal (Arctocephalus gazella) at Hope Bay, Antarctic Peninsula and Stranger Point, South Shetland Islands

et al. 2023

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The relevance of fish in the summer diet of the Antarctic fur seal (Arctocephalus gazella) at Hope Bay, Antarctic Peninsula and Stranger Point, South Shetland Islands

Descalzo

Daneri

Harrington

et al. 2022

Preprint

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The fish incidence, particularly notothenioids and myctophids, in the diet of non-breeding male Arctocephalus gazella in the western Antarctic Peninsula (AP) region is scarcely known. We made a comparative diet analysis on 158 faecal samples collected in summer 2005 at Hope Bay (HB), AP and at Stranger Point (SP), South Shetland Islands (SSI). The occurrence of Antarctic krill Euphausia superba and fish as prey was similar at HB, whereas krill was predominant at SP. For each fish species identified based on the otoliths found, their relative importance in the diet was evaluated using the IRI index. Notothenioid fish prevailed at HB: Pleuragramma.antarctica was the most important prey followed by Chaenodraco wilsoni. Contrarily, myctophids predominated at SP: Gymnoscopelus nicholsiand Electrona antarctica were the dominant prey. Both benthopelagic and pelagic fish species were represented at HB, while the latter were more important at SP; we suggest that seals from SP are foraging in pelagic strata, while at HB their habitat includes benthic and pelagic environments. Demersal nototheniid species were scarcely represented and only at HB, which might be related to a preference of fur seals on the more abundant pelagic prey there. At SP, the absence of demersal nototheniid otoliths in the faeces could be linked to the historical finfish fisheries that took place in the SSI area. On fish species consumption, there was a higher diversity at SP in comparison with HB but a low overlap between these sites. Our findings are compared with studies from localities of the AP and the Scotia Arc.

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Ecosystem shifts inferred from long-term stable isotope analysis of male Antarctic fur seal Arctocephalus gazella teeth

Lima

Cebuhar

Negrete

et al. 2022

Mar. Ecol. Prog. Ser.

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The Atlantic sector of the Southern Ocean has been rapidly changing over the last century. Many of those changes are driven by climate anomalies such as the El Niño-Southern Oscillation and the Southern Annular Mode, which affect biological processes that scale up the food web. We used δ13C and δ15N time series of dentine growth layer groups (as a proxy of individual foraging history from multiple years, n = 41 teeth) to assess temporal shifts in foraging habits of subadult/adult male Antarctic fur seals Arctocephalus gazella (AFSs) in 2 areas of high concentration of Antarctic krill Euphausia superba: the South Shetland Islands and the South Orkney Islands. Our analyses, which represent the first long-term isotopic assessment of male AFS sampled in Antarctic waters, revealed a significant decrease of δ13C (0.04‰ yr-1) from 1974 to 2015 and a decrease of δ15N after the late 1990s. The observed changes are likely driven by shifts in latitudinal and longitudinal distribution of krill and increased incorporation of 15N-enriched sources (higher trophic level prey and/or feeding in different areas) in the most recent period for reasons that are not yet clear. We were able to trace ecosystem changes through isotopic bio-archives of Antarctic fur seals, highlighting the role of this species as an ecosystem indicator of the trophic cascade effects caused by climate change in the Southern Ocean.

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Comparative analysis of the diet of Arctocephalus gazella (Pinnipedia), at two localities of the South Shetland Islands, with emphasis on the fish component

Cited by 3 publications

References 30 publications

The relevance of fish in the summer diet of the Antarctic fur seal (Arctocephalus gazella) at Hope Bay, Antarctic Peninsula and Stranger Point, South Shetland Islands

The relevance of fish in the summer diet of the Antarctic fur seal (Arctocephalus gazella) at Hope Bay, Antarctic Peninsula and Stranger Point, South Shetland Islands

The relevance of fish in the summer diet of the Antarctic fur seal (Arctocephalus gazella) at Hope Bay, Antarctic Peninsula and Stranger Point, South Shetland Islands

Ecosystem shifts inferred from long-term stable isotope analysis of male Antarctic fur seal Arctocephalus gazella teeth

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