Isotopic niche overlap and partition among three Antarctic seals from the Western Antarctic Peninsula

Botta, Silvina; Secchi, Eduardo R.; Rogers, Tracey L.; Prado, Jonatas Henrique; Lima, Renan C. de; Carlini, Pedro; Negrete, Javier

doi:10.1016/j.dsr2.2017.11.005

Cited by 30 publications

(38 citation statements)

References 86 publications

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“…This is the first study on the diet of Weddell seals of Terra Nova Bay, and our results (TL > 5 and mean δ 15 N = 15.7‰) confirmed that this species occupies a top trophic position among phocids within the Antarctic ecosystem (e.g., Pinkerton & Bradford-Grieve 2014;Goetz et al 2017;Botta et al 2018). As upper trophic-level species, its responses to changes in the low levels of the food chain due to environmental variations would be amplified and affect its diet, reproductive performance, and population size (Erikstad et al 1998;Orzack & Tuljapurkar 2001;Hindell et al 2003;Le Boeuf & Crocker 2005;Reid et al 2005).…”

Section: Discussionsupporting

confidence: 80%

“…They feed primarily on fish from the Nototheniidae family (i.e., toothfish) and cephalopods (Dearborn 1965;Plötz et al 1991;Burns et al 1998), although some variations in food resources are expected, as they move from the open ocean to the coast, where they breed. So far, most studies on their diet analysed scats or stomach contents (but see Goetz et al 2017, Botta et al 2018 and have been restricted to the colonies of McMurdo; sampling is normally done when they are tied to the fast ice to breed (September-November), and hence easily accessible from research stations (Davis et al 1982;Casaux et al 1997;Lake et al 2003;Daneri et al 2012). However, since the results of these methods are based on the remains of the hard parts of prey, they might not reflect the whole predator diet, as soft prey or those only partially eaten (Ainley & Siniff 2009) may not be present in the analysed samples (Ponganis & Stockard 2007;Kooyman 2013).…”

Section: Introductionmentioning

confidence: 99%

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The diet of Weddell seals (Leptonychotes weddellii) in Terra Nova Bay using stable isotope analysis

Rumolo

Zappes

Fabiani

et al. 2020

The European Zoological Journal

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Section: Discussionsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

The diet of Weddell seals (Leptonychotes weddellii) in Terra Nova Bay using stable isotope analysis

Rumolo

Zappes

Fabiani

et al. 2020

The European Zoological Journal

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“…Baleen whales, feeding on krill, show migratory patterns that are complex and flexible, presumably adapting to food availability (Thomisch et al, ). Leopard seals, inhabiting the pack ice, also consume krill in variable amounts (12–90% of their diet), but they complement their diet with fish, penguins, other seals and cephalopods (Figure ; Botta et al, ). Crabeater seals also inhabit pack ice and consume mostly krill.…”

Section: Biology Ii: Food Web Of the Wgmentioning

confidence: 99%

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

148

147

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The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures, and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide, and global modeling efforts—thereby enhancing predictions of the WG in global ocean circulation and climate.

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“…This complexity can limit our ability to interpret stable isotope results including the various niche metrics. For example, differences in resource availability and the isotopic signatures of basal sources among communities influence the positions of consumers in bivariate space Layman et al, 2007 In most isotopic studies, the foraging behaviour of individuals is unknown and inferred from the isotopic data themselves (Botta et al, 2017;Galetti et al, 2016;Gallagher et al, 2017;Sepulveda et al, 2012;Staudinger et al, 2014). Even when corrected for resource or basal (end-member) signatures (via mixing models; Newsome et al, 2007;Newsome et al, 2012;Post, 2002), niche estimates are difficult to compare among study systems.…”

Section: Discussionmentioning

confidence: 99%

“…The package also produces estimates of sampling error. Indeed, most current studies of dietary specialization, niche partitioning and competition among individuals, populations and species rely on MCP and SEA techniques to delineate isotopic niche estimates (Botta et al, ; Galetti, Rodarte, Neves, Moreira, & Costa‐Pereira, ; Gallagher, Shiffman, Byrnes, Hammerschlag‐Peyer, & Hammerschlag, ; Staudinger, McAlarney, McLellan, & Pabst, ; but see Sepulveda, Lowe, & Marra, ).…”

Section: Introductionmentioning

confidence: 99%

rKIN: Kernel‐based method for estimating isotopic niche size and overlap

Eckrich

Albeke

Flaherty

et al. 2020

Journal of Animal Ecology

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The isotopic niche of consumers represents biologically relevant information on resource and habitat use. Several tools have been developed to quantify niche size and overlap. Nonetheless, methods adapted by spatial ecologists to quantify animal home ranges can be modified for use in stable isotope ecology when data are not normally distributed in bivariate space. We offer a tool that draws on existing spatial metrics, such as minimum convex polygon (MCP) and standard ellipse area (SEA), and add novel metrics using kernel utilization density (KUD) estimators to measure isotopic niche size and overlap. We present examples using empirical and simulated data to demonstrate the performance of the package kernel isotopic niches in r (rKIN) under various scenarios. Results of niche size from MCP, SEA and KUD were highly correlated but divergent among datasets. Overall, the KUD method produced the largest niche sizes and was more sensitive to the distribution of the isotopic data. Pairwise estimates of overlap were highly variable, likely because MCP and SEA inherently include or exclude unused areas in the resulting niche estimate. Four bandwidth methods (reference, normal scale, plug‐in and biased cross‐validation) produced comparable estimates of niche size and overlap at various sample sizes (10–40). Niche size and overlap were consistent across sample sizes >15. Use of rKIN will allow isotope ecologists to quantify niche shifts, expansions or contractions, as well as assess the performance of several estimation methods. The package also can be applied to other data types (e.g. principal component analysis, multi‐dimensional scaling) so long as axes and measurement units are identical and can be converted to Cartesian coordinates.

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Isotopic niche overlap and partition among three Antarctic seals from the Western Antarctic Peninsula

Cited by 30 publications

References 86 publications

The diet of Weddell seals (Leptonychotes weddellii) in Terra Nova Bay using stable isotope analysis

The diet of Weddell seals (Leptonychotes weddellii) in Terra Nova Bay using stable isotope analysis

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

rKIN: Kernel‐based method for estimating isotopic niche size and overlap

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