Foraging behaviour of Weddell seals (Leptonychotes weddellii) in connection to oceanographic conditions in the southern Weddell Sea

Nachtsheim, Dominik; Ryan, Svenja; Schröder, Michael; Jensen, Laura; Oosthuizen, W. Chris; Bester, Marthán N; Hagen, Wilhelm; Bornemann, Horst

doi:10.1016/j.pocean.2019.02.013

Cited by 25 publications

(45 citation statements)

References 85 publications

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“…The absence of Weddell seals during the ship-board survey attests to their primary use of fast ice and nearby pack ice habitats close to the coast during the breeding season (LaRue et al, 2019;Nachtsheim et al, 2019;Southwell et al, 2012).…”

Section: Weddell Sealsmentioning

confidence: 99%

Antarctic pack ice seal observations during spring across the Lazarev Sea

et al. 2021

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The distribution, density and percentage contribution of pack ice seals during ship-board censuses in the marginal sea ice zone beyond the Lazarev Sea in spring 2019 are presented. Adult/juvenile crabeater seals (n = 19), leopard seals (n = 3) and Ross seals (n = 10) were sighted during 582.2 nm of censuses along the ship’s track line in the area bounded by 00°00’–22°E and 56°–60°S. Antarctic fur seals (n = 21) were only encountered on the outer fringes of the pack ice, and Weddell seals were absent due to their primary use of fast ice and inner pack ice habitats close to the coast. Crabeater seal sightings included juveniles (n = 2) and another four groups of 2–3 unclassified crabeater seals, singletons (n = 5), single mothers with pups (n = 3) and a family group (n = 1 triad). Only one leopard seal attended a pup, while no Ross seal pups were located. The survey was likely of insufficient effort, in both extent (north of 60°S) and duration (18 days), to locate seals in considerable numbers this early (late October/early November) in their austral spring breeding season.

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Section: Weddell Sealsmentioning

confidence: 99%

Antarctic pack ice seal observations during spring across the Lazarev Sea

et al. 2021

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“…In contrast, the southern Weddell Sea is only accessible by ship during austral summer. The interaction of Weddell seals with the hydrographically complex and varied Weddell Sea vertical habitat is not currently understood (but see [30][31][32]) and is likely to be different, owing to the availability of different water masses and deep ocean habitat. Previous work on foraging ecology in the Weddell Sea has found that dives target the surface, shallow epipelagic, and the mesopelagic region [30,[33][34][35], while commuting through intermediate depths.…”

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confidence: 99%

Sex-specific variation in the use of vertical habitat by a resident Antarctic top predator

et al. 2020

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Patterns of habitat use are commonly studied in horizontal space, but this does not capture the four-dimensional nature of ocean habitats (space, depth, and time). Deep-diving marine animals encounter varying oceanographic conditions, particularly at the poles, where there is strong seasonal variation in vertical ocean structuring. This dimension of space use is hidden if we only consider horizontal movement. To identify different diving behaviours and usage patterns of vertically distributed habitat, we use hidden Markov models fitted to telemetry data from an air-breathing top predator, the Weddell seal, in the Weddell Sea, Antarctica. We present evidence of overlapping use of high-density, continental shelf water masses by both sexes, as well as important differences in their preferences for oceanographic conditions. Males spend more time in the unique high-salinity shelf water masses found at depth, while females also venture off the continental shelf and visit warmer, shallower water masses. Both sexes exhibit a diurnal pattern in diving behaviour (deep in the day, shallow at night) that persists from austral autumn into winter. The differences in habitat use in this resident, sexually monomorphic Antarctic top predator suggest a different set of needs and constraints operating at the intraspecific level, not driven by body size.

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“…Padman et al (2010), for example, used seal profiles to improve bathymetric maps of the continental shelf of the western Antarctic peninsula. Characteristics of the dive behavior show that approximately 30% of Elephant and Weddell seal dives are benthic foraging dives (Nachtsheim et al, 2019; Padman et al, 2010), with most dives on the continental shelf reaching the seabed (McConnell & Fedak, 1996). The Argos satellite positions obtained by the seals are less accurate than GPS and may be in error by tens to hundreds of kilometers (e.g.…”

Section: Discussionmentioning

confidence: 99%

Bathymetry‐Constrained Navigation of Argo Floats Under Sea Ice on the Antarctic Continental Shelf

Wallace

Wijk

Rintoul

et al. 2020

Geophysical Research Letters

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Antarctic continental shelf waters are poorly sampled, particularly beneath sea ice during winter. Profiling floats could help fill this gap, but floats are unable to surface to obtain a satellite position when ice is present. We deployed Argo profiling floats in a coastal polynya with a novel mission to rest on the sea floor between profiles. “Parking” on the seabed minimized the drift of the floats and allowed year‐round, full‐depth measurements over multiple winters. Measurements of water depth derived from the floats were used in combination with known bathymetry to constrain the position of profiles collected under ice. Errors were quantified by withholding known positions and comparing them to estimated positions; the bathymetrically constrained algorithm outperformed linear interpolation. A similar approach could potentially be used to geolocate other under‐ice oceanographic platforms that measure water depth.

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Foraging behaviour of Weddell seals (Leptonychotes weddellii) in connection to oceanographic conditions in the southern Weddell Sea

Cited by 25 publications

References 85 publications

Antarctic pack ice seal observations during spring across the Lazarev Sea

Antarctic pack ice seal observations during spring across the Lazarev Sea

Sex-specific variation in the use of vertical habitat by a resident Antarctic top predator

Bathymetry‐Constrained Navigation of Argo Floats Under Sea Ice on the Antarctic Continental Shelf

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