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

Rumolo, Paola; Zappes, Ighor Antunes; Fabiani, Anna; Barra, Marco; Rakaj, Arnold; Palozzi, Roberto; Allegrucci, Giuliana

doi:10.1080/24750263.2020.1720832

Cited by 5 publications

(3 citation statements)

References 81 publications

(88 reference statements)

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“…Shifts in the migratory behavior of Antarctic Silverfish due to changes in environmental conditions could have bottom-up effects on the condition and location of regional populations of Antarctic Toothfish 82 . Furthermore, some species of seals, especially the Weddell seal ( Leptonychotes weddellii ), heavily consume both Antarctic Toothfish and Silverfish 83 – 85 . Changes in the occurrence of Antarctic Silverfish could cause Weddell seal populations to increase their predation pressure on Antarctic Toothfish, or other fishes.…”

Section: Resultsmentioning

confidence: 99%

Climate drives long-term change in Antarctic Silverfish along the western Antarctic Peninsula

et al. 2022

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Over the last half of the 20th century, the western Antarctic Peninsula has been one of the most rapidly warming regions on Earth, leading to substantial reductions in regional sea ice coverage. These changes are modulated by atmospheric forcing, including the Amundsen Sea Low (ASL) pressure system. We utilized a novel 25-year (1993–2017) time series to model the effects of environmental variability on larvae of a keystone species, the Antarctic Silverfish (Pleuragramma antarctica). Antarctic Silverfish use sea ice as spawning habitat and are important prey for penguins and other predators. We show that warmer sea surface temperature and decreased sea ice are associated with reduced larval abundance. Variability in the ASL modulates both sea surface temperature and sea ice; a strong ASL is associated with reduced larvae. These findings support a narrow sea ice and temperature tolerance for adult and larval fish. Further regional warming predicted to occur during the 21st century could displace populations of Antarctic Silverfish, altering this pelagic ecosystem.

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Section: Resultsmentioning

confidence: 99%

Climate drives long-term change in Antarctic Silverfish along the western Antarctic Peninsula

et al. 2022

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“…This micro-habitat migration in P. lividus closely matches the feeding requirement shift that emerged in our study, leading us to hypothesize that this may be the root cause or a contributing cause of the sheltering behavior. Then, stable isotope analysis may be a promising tool in order to further investigate this topic as a function of resource availability and habitat features in the natural environment (Boncagni et al, 2019;Camps-Castellà et al, 2020;Rumolo et al, 2020)…”

Section: General Considerations On P Lividus Ecology and Trophic Beha...mentioning

confidence: 99%

Trophic Requirements of the Sea Urchin Paracentrotus lividus Varies at Different Life Stages: Comprehension of Species Ecology and Implications for Effective Feeding Formulations

et al. 2022

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Investigations on trophic requirements of different life cycle stages of Paracentrotus lividus are crucial for the comprehension of species ecology and for its artificial rearing. The future success of echinoculture depends heavily on the development of suitable and cost-effective diets that are specifically designed to maximize somatic growth during the early life stages and gonadal production in the later stages. In this context, a considerable number of studies have recommended animal sources as supplements in sea urchin diets. However, with the exception of Fernandez and Boudouresque (2000), no studies have investigated the dietary requirements over the different life stages of the sea urchin. In the present study, the growth and nutrition of three life stages of P. lividus (juveniles: 15-25 mm; subadults: 25-35 mm; adults: 45-55 mm) were analyzed over a 4-month rearing experiment. Three experimental diets, with 0%, 20% and 40% of animal sourced enrichments, were tested in parallel in sea urchin three size classes. The food conversion ratio, somatic and gonadal growth were assessed in each condition in order to evaluate the optimal level of animal-sourced supplements for each life stage. A general growth model covering the full post-metamorphic P. lividus life cycle was defined for each condition. During the juvenile stage P. lividus requires higher animal supply (40%), while a feeding requirement shift takes place toward lower animal supply (20%) in sub-adult and adult stages. Our results evidenced that the progressive increase in size after the metamorphosis led to a consequent variation of trophic requirements and food energy allocation in the sea urchin P. lividus. Macronutrient requirements varied widely during the different life stages, in response to changes in the energy allocation from somatic growth to reproductive investment. This study sheds light on P. lividus trophic ecology, broadening our basic knowledge of the dietary requirements of juveniles, sub-adults and adults as a function of their behavior also in the natural environment.

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“…Ainley et al (2021) also suggested Weddell seal abundance may impact the toothfish scientific catchper-unit-effort, with fewer fish being caught during Weddell seal population peaks. The prey targeted by Weddell seals also varies across location, season, and age-groups (Lindsay 1937;Burns et al 1998;Rumolo et al 2020), and research suggests they may show behavioural plasticity in prey selection, being able to adapt prey targeted to what is available (Foster-Dyer et al in review).…”

Section: Introductionmentioning

confidence: 99%

First observations of Weddell seals foraging in sponges in Erebus Bay, Antarctica

Foster-Dyer,

Goetz,

Pinkerton

et al. 2023

Polar Biol

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Attaching cameras to marine mammals allows for first-hand observation of underwater behaviours that may otherwise go unseen. While studying the foraging behaviour of 26 lactating Weddell seals (Leptonychotes weddellii) in Erebus Bay during the austral spring of 2018 and 2019, we witnessed three adults and one pup investigating the cavities of Rossellidae glass sponges, with one seal visibly chewing when she removed her head from the sponge. To our knowledge, this is the first report of such behaviour. While the prey item was not identifiable, some Trematomus fish (a known Weddell seal prey) use glass sponges for shelter and in which to lay their eggs. Three of the four sponge foraging observations occurred around 13:00 (NZDT). Two of the three sponge foraging adults had higher-than-average reproductive rates, and the greatest number of previous pups of any seal in our study population, each having ten pups in 12 years. This is far higher than the study population average of three previous pups (± 2.6 SD). This novel foraging strategy may have evolved in response to changes in prey availability, and could offer an evolutionary advantage to some individuals that exploit prey resources that others may not. Our observations offer new insight into the foraging behaviours of one of the world’s most studied marine mammals. Further research on the social aspects of Weddell seal behaviour may increase our understanding of the extent and mechanisms of behavioural transfer between conspecifics. Research into the specific foraging behaviour of especially successful or experienced breeders is also warranted.

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

Cited by 5 publications

References 81 publications

Climate drives long-term change in Antarctic Silverfish along the western Antarctic Peninsula

Climate drives long-term change in Antarctic Silverfish along the western Antarctic Peninsula

Trophic Requirements of the Sea Urchin Paracentrotus lividus Varies at Different Life Stages: Comprehension of Species Ecology and Implications for Effective Feeding Formulations

First observations of Weddell seals foraging in sponges in Erebus Bay, Antarctica

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