Trophic ecology of the squid Doryteuthis gahi in the Southwest Atlantic inferred from stable isotope analysis

Büring, Tobias; Jones, Jessica B.; Pierce, Graham J.; Rocha, Francisco; Bustamante, Paco; Brault‐Favrou, Maud; Arkhipkin, Alexander I.

doi:10.1016/j.ecss.2023.108300

Cited by 2 publications

(2 citation statements)

References 55 publications

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“…Many species in intermediate trophic levels were pooled as 'predatory/omnivorous', because of complex ontogenetic diet changes or uncertainty of their feeding behaviour. D. gahi was split into ASC and SSC individuals based on Arkhipkin et al (2013) and Büring et al (2022Büring et al ( , 2023 to allow direct comparisons of TLs based on stable isotopes vs the Ecopath model. Species with less than three samples were excluded from the Bayesian analysis (Table 1).…”

Section: Statisticsmentioning

confidence: 99%

“…Another relevant adjustment concerns the modelling of D. gahi, with two cohorts considered separately. This choice enabled assessing their particular importance in the ecosystem and the fact that maturity stages of both cohorts differ in both spatial and temporal distribution and were found to have different trophic ecology (Büring et al, 2022(Büring et al, , 2023Jones et al, 2023). The inclusion in the model of two cohorts allowed us to consider their mutual predation.…”

Section: Ecopath Modelmentioning

confidence: 99%

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Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Büring,

van Der Grient,

Pierce

et al. 2024

J. Mar. Biol. Ass.

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The Falkland Shelf is a highly productive ecosystem in the Southwest Atlantic Ocean. It is characterized by upwelling oceanographic dynamics and displays a wasp-waist structure, with few intermediate trophic-level species and many top predators that migrate on the shelf for feeding. One of these resident intermediate trophic-level species, the Patagonian longfin-squid Doryteuthis gahi, is abundant and plays an important role in the ecosystem. We used two methods to estimate the trophic structure of the Falkland Shelf food web, focusing on the trophic niche of D. gahi and its impacts on other species and functional groups to highlight the importance of D. gahi in the ecosystem. First, stable isotope measurements served to calculate trophic levels based on an established nitrogen baseline. Second, an Ecopath model was built to corroborate trophic levels derived from stable isotopes and inform about trophic interactions of D. gahi with other functional groups. The results of both methods placed D. gahi in the centre of the ecosystem with a trophic level of ~ 3. The Ecopath model predicted high impacts and therefore a high keystoneness for both seasonal cohorts of D. gahi. Our results show that the Falkland Shelf is not only controlled by species feeding at the top and the bottom of the trophic chain. The importance of species feeding at the third trophic level (e.g. D. gahi and Patagonotothen ramsayi) and observed architecture of energy flows confirm the ecosystem's wasp-waist structure with middle-out control mechanisms at play.

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Section: Statisticsmentioning

confidence: 99%

Section: Ecopath Modelmentioning

confidence: 99%

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Büring,

van Der Grient,

Pierce

et al. 2024

J. Mar. Biol. Ass.

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Seal-fishery interactions in the Falkland Islands—operational and environmental factors drive resource competition

Riaz,

Büring,

van der Grient

et al. 2024

ICES Journal of Marine Science

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Direct interactions between marine mammals and commercial fisheries are a worldwide conservation challenge. Observer programmes remain the most effective and reliable method for collecting data on these interactions. In the Falkland Islands—home to globally significant seal populations and commercial squid fisheries, seal-fishery interactions have escalated in recent years, prompting management concerns. Complete observer coverage within the squid fishery presents a valuable opportunity to investigate the nature, extent, and drivers of these interactions. Integrating multi-year observer records with extensive ancillary (i.e. vessel logbook and oceanographic) datasets, we examine the operational and environmental factors influencing the occurrence of seal-fishery interactions. Our findings show interactions most frequently occur in the main squid fishing grounds during trawls associated with high catch quantities. Assessment of long-term catch data (both finfish and squid) also suggests the increase in seal-fishery interactions may be caused by collapses in dominant finfish stocks over the past 20 years, constricting foraging resources available to seals. Taken together, our findings indicate resource competition may be a mechanism of interactions. To help mitigate this issue, we advocate for the development of ecosystem-based fisheries management, which considers the trophic effects of fishing practices and the energetic requirements of local marine predator populations.

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Trophic ecology of the squid Doryteuthis gahi in the Southwest Atlantic inferred from stable isotope analysis

Cited by 2 publications

References 55 publications

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Seal-fishery interactions in the Falkland Islands—operational and environmental factors drive resource competition

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