Intrapopulation variations in diet and habitat use in a marine apex predator, the broadnose sevengill shark Notorynchus cepedianus

Abrantes, Kátya G.; Barnett, Adam

doi:10.3354/meps09395

Cited by 47 publications

(41 citation statements)

References 67 publications

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“…The lack of an ontogenetic relationship between the size of bull sharks and δ 15 N was, however, in contrast to some of these studies [16,22,70]. This was most likely due to the limited size range of individuals sampled in this study and the absence of juveniles from the study site.…”

Section: Discussioncontrasting

confidence: 84%

“…The relatively slow isotopic turnover rate of elasmobranch muscle tissue [13] may also mean that sharks foraging between different habitats will not reach isotopic equilibrium with one habitat which makes the interpretation of these data difficult. This may mean that the isotopic signatures reflected by these muscle tissues are in fact a mix of the dietary contributions from all frequented habitats [22] and may not reflect specific dietary contributions from the study site. However, these signatures may still provide a relative measure between individual bull sharks that reflect the differences between foraging ranges.…”

Section: Discussionmentioning

confidence: 99%

“…Refined by recent progress in the application of stable carbon and nitrogen isotope analysis to study elasmobranchs [12-15], the associated methodology is a robust and complementary tool for investigating the trophic ecology of elasmobranchs. The application of SIA provides insight into various population, species and individual level processes including the trophic position [11,16], niche width and overlap [17], ontogenetic dietary shifts [18,19], species foraging strategies [20] individual foraging strategies [19,21], and habitat use [22-24] of large sharks.…”

Section: Introductionmentioning

confidence: 99%

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Comparative Feeding Ecology of Bull Sharks (Carcharhinus leucas) in the Coastal Waters of the Southwest Indian Ocean Inferred from Stable Isotope Analysis

2013

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As apex predators, sharks play an important role shaping their respective marine communities through predation and associated risk effects. Understanding the predatory dynamics of sharks within communities is, therefore, necessary to establish effective ecologically based conservation strategies. We employed non-lethal sampling methods to investigate the feeding ecology of bull sharks (Carcharhinus leucas) using stable isotope analysis within a subtropical marine community in the southwest Indian Ocean. The main objectives of this study were to investigate and compare the predatory role that sub-adult and adult bull sharks play within a top predatory teleost fish community. Bull sharks had significantly broader niche widths compared to top predatory teleost assemblages with a wide and relatively enriched range of δ13C values relative to the local marine community. This suggests that bull sharks forage from a more diverse range of δ13C sources over a wider geographical range than the predatory teleost community. Adult bull sharks appeared to exhibit a shift towards consistently higher trophic level prey from an expanded foraging range compared to sub-adults, possibly due to increased mobility linked with size. Although predatory teleost fish are also capable of substantial migrations, bull sharks may have the ability to exploit a more diverse range of habitats and appeared to prey on a wider diversity of larger prey. This suggests that bull sharks play an important predatory role within their respective marine communities and adult sharks in particular may shape and link ecological processes of a variety of marine communities over a broad range.

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Section: Discussioncontrasting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparative Feeding Ecology of Bull Sharks (Carcharhinus leucas) in the Coastal Waters of the Southwest Indian Ocean Inferred from Stable Isotope Analysis

2013

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“…Although stable isotopes have been successfully used in shark species to examine animal origin and movement (e.g. Abrantes & Barnett 2011, it is very difficult to work at a scale of < 6 mo (minimum turnover time for the plasma), especially if the difference in isotopic values related to trophic shift is small.…”

Section: Caveats In Applying Stable Isotopes In the Study Of Sharksmentioning

confidence: 99%

Diet- and tissue-specific incorporation of isotopes in the shark Scyliorhinus stellaris, a North Sea mesopredator

Caut¹,

Jowers²,

Michel³

et al. 2013

Mar. Ecol. Prog. Ser.

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14Elucidating predator-prey relationships is an important part of understanding and assessing the 15 structure and function of ecosystems. Sharks are believed to play a significant role in marine 16 ecosystems, although their specific trophic ecology is largely unexplored. Stable isotopes of 17 nitrogen (δ 15 N) and carbon (δ 13 C) are a widely applied tool in food web studies but there is a 18 need to quantify stable isotope dynamics in animals, particularly sharks. In this study, diet-tissue 19 discrimination factors (DTDF = stable isotope in consumer tissue -stable isotope in diet) and 20 turnover rates (time for the isotope to be assimilated into the consumer's tissue) of stable 21 isotopes were estimated in blood, fin, and muscle tissue for the shark species Scyliorhinus 22 stellaris fed two diets with different isotope values. Subsequently, these diet-and tissue-specific 23DTDFs were used in isotopic mixing models to quantify the diet of Scyliorhinus canicula caught 24 in the North Sea and compared with stomach content data. DTDFs for δ 15 N (∆ 15 N) and δ 13 C 25 (∆ 13 C) ranged from -1.95‰ to 3.49‰ and from 0.52‰ to 5.14‰, respectively, and varied with 26 tissue and diet type. Isotope turnover rates in plasma and red blood cells, expressed as half-lives, 27 range from 39 to 135 days. A majority of the variability of DTDFs reported in this and other 28 studies with sharks can be explained by linear relationships between DTDF and dietary isotopic 29 values. From these relationships, we propose a method for isotope mixing models that uses diet-30 specific DTDFs, which improves diet reconstruction estimates of animals, particularly 31 mesopredator sharks that consume a large range of prey types. 32 33

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“…Despite the similar distributions of S. acanthias and M. antarcticus, the diVerence in diet between the two species suggests they show some degree of resource partitioning, and they may forage in diVerent habitats. Stable isotope analysis also suggests that S. acanthias feeds on slightly higher trophic level prey than M. antarcticus in the Derwent River and Norfolk Bay (Abrantes and Barnett 2011). The large amounts of sedentary prey consumed by M. antarcticus, in conjunction with their constant feeding (i.e.…”

Section: Discussionmentioning

confidence: 97%

The trophic ecology of two abundant mesopredators in south-east coastal waters of Tasmania, Australia

2012

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Investigating predator-prey relationships is an important component for identifying and understanding the factors that inXuence the structure and function of ecosystems. Mesopredators, deWned as mid-level predators, have a profound eVect on ecosystem structure by contributing an important link between apex predators and lower trophic levels. The diet of two elasmobranch mesopredators, Squalus acanthias and Mustelus antarcticus, was investigated in three locations in south-east Tasmania. Squalus acanthias consumed predominantly pelagic teleosts and cephalopods, while M. antarcticus predominantly consumed benthic crustaceans. As a result, there was low dietary and niche overlap between the two species. There was however evidence of intra-speciWc dietary variations between locations for both the species. This study has contributed to a better understanding of the top-down dynamics of the food web in coastal Tasmania, by providing important dietary information of two abundant mesopredators. In addition, the similar dietary patterns for S. acanthias and other Mustelus species over much of their global range suggest they may be consistent in their trophic roles across systems, with limited competition between these two sympatric mesopredators to be expected.

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Intrapopulation variations in diet and habitat use in a marine apex predator, the broadnose sevengill shark Notorynchus cepedianus

Cited by 47 publications

References 67 publications

Comparative Feeding Ecology of Bull Sharks (Carcharhinus leucas) in the Coastal Waters of the Southwest Indian Ocean Inferred from Stable Isotope Analysis

Comparative Feeding Ecology of Bull Sharks (Carcharhinus leucas) in the Coastal Waters of the Southwest Indian Ocean Inferred from Stable Isotope Analysis

Diet- and tissue-specific incorporation of isotopes in the shark Scyliorhinus stellaris, a North Sea mesopredator

The trophic ecology of two abundant mesopredators in south-east coastal waters of Tasmania, Australia

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