scholarly journals Feeding patterns of two sympatric shark predators in coastal ecosystems of an oceanic island

2017 ◽  
Vol 74 (2) ◽  
pp. 216-227 ◽  
Author(s):  
Clément Trystram ◽  
Karyne M. Rogers ◽  
Marc Soria ◽  
Sébastien Jaquemet
Keyword(s):  
Trophic Ecology ◽  
Dietary Habits ◽  
Stomach Contents ◽  
Nitrogen Isotope ◽  
Oceanic Island ◽  
Apex Predators ◽  
Coastal Habitat ◽  
Galeocerdo Cuvier ◽  
Carcharhinus Leucas ◽  
Bull Shark

Stomach contents and stable carbon and nitrogen isotope analyses (δ13C and δ15N) were used to investigate the trophic ecology of two apex predators, tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas), from Reunion Island to describe their dietary habits at both the population and individual levels. In this oceanic island, the tiger and bull sharks were more piscivorous and teutophagous than noted in previous research from other localities. The δ13C values suggested that bull sharks depended on more neritic organic matter sources than tiger sharks, confirming a coastal habitat preference for bull sharks. Moreover, the total length of the bull shark influenced δ13C values, with smaller individuals being more coastal than larger individuals. All indicators suggest that there is a higher degree of similarity between individual tiger sharks compared with the more heterogeneous bull shark population, which is composed of individuals who specialize on different prey. These results suggest that the two species have different functions in these coastal habitats, and thus, they must be considered independently in terms of conservation and management.

scholarly journals Notes on the Bull shark Carcharhinus leucas in the lagoon region of Cananéia, Brazil

1971 ◽  
Vol 20 (2) ◽  
pp. 71-78 ◽  
Author(s):  
V Sadowsky
Keyword(s):  
Stomach Contents ◽  
Abundant Species ◽  
Feeding Inhibition ◽  
Adult Females ◽  
Carcharhinus Leucas ◽  
Caudal Vertebrae ◽  
Open Sea ◽  
Bull Shark

Ninety one young specimens and 3 adult females of BulI shark ("cação cabeça chata") caught in the lagoon region of Cananéia were examined, their tooth formula being 27/25 and the number of pre-caudal vertebrae ranging from 109 to 115. The proportion between the 1st and 2nd dorsal fins were found to be 2.3 and 2.8 for the young,and 2.9 to 3.1 for the adults. These data confirm that the studied form belongs to C. leuoas. Young occur regularly but in limited numbers.As regards the adults, however, females only appear during the short parturition period, i.e., from November to February. The number of embryos in the litters were from 7 to 9, their sizes ranging between 768-812 mm. The length of the smallest free young found was 697 mm, but young presumably 9 to 12 months old had 98 to 112 cm; between 21 and 24 months they were reaching 124 to 128 cm, that is, the same size they have when they start migrating to the open sea. The feeding inhibition phenomenon during the period of parturition was not observed in the female specimens caught in the lagoon. The more abundant species found in the stomach contents were: Arius spixii; Chloroscombrus chrysurus; A. grandicassus; A. barbus; Felichtys marinus; Genidens genidens; Chanophorus tajacica and Carcharhinus porosus.

scholarly journals Ecología trófica y rasgos ecomorfológicos de Triportheus magdalenae (Characiformes: Triportheidae) en el embalse El Guájaro, cuenca baja del río Magdalena, Colombia

2018 ◽  
Vol 66 (3) ◽  
pp. 1208
Author(s):  
Jenny Morales ◽  
Carlos Arturo García-Alzate
Keyword(s):  
Trophic Ecology ◽  
Dietary Habits ◽  
Morphological Characteristics ◽  
Stomach Contents ◽  
Relative Length ◽  
Flood Pulse ◽  
Trophic Niche ◽  
Trophic Specialization ◽  
Magdalena River ◽  
Del Rio

This study integrated morphological characteristics and trophic ecology of Triportheus magdalenae in the El Guájaro reservoir, Atlántico, lower Magdalena River Basin, Colombia, based on the analysis of stomach contents and ecomorphological attributes. Five samplings were made between September 2014 and February 2016 considering each phase of the flood pulse. The fish were sampled using traditional fishing gear such as nets and trawls. The index of food importance (IAi %) was used to establish the dietary habits of the species, and the variation of the diet at interspecific level, and the vacuity coefficient (CV %) was also calculated. The Levins index standardized by Hurlbert (BA) was used to evaluate the amplitude between sizes, sex and hydrological phases. The oropharyngeal structures and the digestive tract were characterized, which together with morphological measurements, allowed and analyze 11 ecomorphological traits related to the use of habitat, such as position in the water column, and the exploitation of a particular trophic resource. The relationship between the ecomorphological traits and the diet of the species was analyzed by canonical correspondence analysis (CCA). We analyzed 89 individuals (34 - 124 mm SL). Triportheus magdalenae was classified as carnivore/zooplanktivore, and has a narrow trophic niche (BA = 0.12). Showed a high exploitation of zooplankton (95.9 % IAi), mostly Cladocera (Ceriodaphnia sp.) and Copepoda (Notodiaptomus sp. and Thermocyclops sp).  The youngest juveniles (34 - 190 mm SL) also consumed allochthonous insects (3.4 % IAi).The ecomorphological traits that contributed the most to this trophic specialization were the relative length of the gillrakers (LRBE) and the number of gillrakers (NBE), which varied significantly from the smaller to the larger ones, with an increase in both number as well as in length as individuals grow, which explains the strongly marked degree of specialization on zooplankton in adults, since they present a greater degree of efficiency in the process of filtering. The vacuity coefficient was high  (54 %), which could be associated with a decrease in the density of zooplankton populations, especially during the time of lower waters strongly influenced by the EL NIÑO event, however the observed diet (22 items food) corresponded to 80 % of the diet estimated (28 estimated food items). 

scholarly journals Diet of the bull shark, Carcharhinus leucas, and the tiger shark,Galeocerdo cuvier, in the eastern Pacific Ocean

2017 ◽  
Vol 41 ◽  
pp. 1111-1117 ◽  
Author(s):  
Colombo ESTUPIÑÁN-MONTAÑO ◽  
José Félix ESTUPIÑÁN-ORTIZ ◽  
Luis Germán CEDEÑO-FIGUEROA ◽  
Felipe GALVÁN-MAGAÑA ◽  
Carlos Julio POLO-SILVA
Keyword(s):  
Pacific Ocean ◽  
Eastern Pacific ◽  
Tiger Shark ◽  
Eastern Pacific Ocean ◽  
Galeocerdo Cuvier ◽  
Carcharhinus Leucas ◽  
Bull Shark

Life after death: behaviour of multiple shark species scavenging a whale carcass

2019 ◽  
Vol 70 (2) ◽  
pp. 302 ◽  
Author(s):  
J. S. E. Lea ◽  
R. Daly ◽  
C. Leon ◽  
C. A. K. Daly ◽  
C. R. Clarke
Keyword(s):  
Indian Ocean ◽  
Western Indian Ocean ◽  
Sperm Whale ◽  
Shark Species ◽  
Tiger Shark ◽  
Nurse Shark ◽  
Life After Death ◽  
Galeocerdo Cuvier ◽  
Carcharhinus Leucas ◽  
Bull Shark

A drone was used to study the richness and behaviour of scavengers attracted to the carcass of a sperm whale (Physeter microcephalus) in Seychelles, Western Indian Ocean. Over 30 sharks of 3 species (tiger shark Galeocerdo cuvier, bull shark Carcharhinus leucas and tawny nurse shark Nebrius ferrugineus) were recorded scavenging on the carcass. Tiger sharks dominated the scavenging, but with no evidence of agonistic behaviours or hierarchy, and may have facilitated scavenging by other species. Drone use allowed the analysis of such behaviours without observer influence, providing new insights into communal scavenging events.

A multi-faceted approach for quantifying the estuarine - nearshore transition in the life cycle of the bull shark, Carcharhinus leucas

2011 ◽  
Vol 62 (12) ◽  
pp. 1421 ◽  
Author(s):  
J. M. Werry ◽  
S. Y. Lee ◽  
N. M. Otway ◽  
Y. Hu ◽  
W. Sumpton
Keyword(s):  
Habitat Use ◽  
Acoustic Telemetry ◽  
Inductively Coupled Plasma ◽  
Stomach Contents ◽  
Inductively Coupled ◽  
Carcharhinus Leucas ◽  
Bull Shark ◽  
Plasma Mass Spectrometry ◽  
Shark Attacks ◽  
Δ15n And Δ13c

Understanding the ontogenetic habitat linkages of sharks is important for conservation and managing human interactions. We used acoustic telemetry, catch data, elemental and stable isotope signatures and dietary analyses to investigate ontogenetic habitat use in south-east Queensland, Australia, by the bull shark Carcharhinus leucas, a IUCN ‘near-threatened’ species that is implicated in many shark attacks on humans in urban estuaries. Sequential analyses for δ15N and δ13C of vertebrae from five adult C. leucas and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) for elemental composition from 23 C. leucas, including a pregnant female, were also used to trace ontogenetic habitat dependence. Acoustic telemetry indicated large juvenile and subadult C. leucas remained in estuarine habitats. δ15N values across shark vertebrae showed an ontogenetic shift in diet with total length (TL), confirmed by stomach contents. LA-ICPMS data reflected the ontogenetic movements of C. leucas from natal habitats. Differences among adults were gender related. Shifts in habitat use by subadults were correlated with a sigmoidal δ13C relationship with TL. C. leucas have a multipartite, stage-specific dependency in their transition between habitats along the freshwater–estuarine–marine continuum, making them particularly susceptible to the habitat alteration that is occurring globally.

scholarly journals Size-based variation in intertissue comparisons of stable carbon and nitrogen isotopic signatures of bull sharks (Carcharhinus leucas) and tiger sharks (Galeocerdo cuvier)

2010 ◽  
Vol 67 (5) ◽  
pp. 877-885 ◽  
Author(s):  
Philip Matich ◽  
Michael R. Heithaus ◽  
Craig A. Layman
Keyword(s):  
Nitrogen Isotope ◽  
Correction Factors ◽  
Isotopic Signatures ◽  
Carbon And Nitrogen ◽  
Galeocerdo Cuvier ◽  
Carcharhinus Leucas ◽  
The Relationship ◽  
Different Tissues ◽  
Slow Turnover ◽  
Study Species

Stable isotopes are important tools for understanding the trophic roles of elasmobranchs. However, whether different tissues provide consistent stable isotope values within an individual are largely unknown. To address this, the relationships among carbon and nitrogen isotope values were quantified for blood, muscle, and fin from juvenile bull sharks ( Carcharhinus leucas ) and blood and fin from large tiger sharks ( Galeocerdo cuvier ) collected in two different ecosystems. We also investigated the relationship between shark size and the magnitude of differences in isotopic values between tissues. Isotope values were significantly positively correlated for all paired tissue comparisons, but R2 values were much higher for δ13C than for δ15N. Paired differences between isotopic values of tissues were relatively small but varied significantly with shark total length, suggesting that shark size can be an important factor influencing the magnitude of differences in isotope values of different tissues. For studies of juvenile sharks, care should be taken in using slow turnover tissues like muscle and fin, because they may retain a maternal signature for an extended time. Although correlations were relatively strong, results suggest that correction factors should be generated for the desired study species and may only allow coarse-scale comparisons between studies using different tissue types.

scholarly journals Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aaron B. Carlisle ◽  
Elizabeth Andruszkiewicz Allan ◽  
Sora L. Kim ◽  
Lauren Meyer ◽  
Jesse Port ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Environmental Dna ◽  
Small Sample ◽  
Apex Predators ◽  
Central Pacific ◽  
Chemical Tracers ◽  
Important Prey ◽  
Tracer Techniques

AbstractThe Cookiecutter shark (Isistius brasiliensis) is an ectoparasitic, mesopelagic shark that is known for removing plugs of tissue from larger prey, including teleosts, chondrichthyans, cephalopods, and marine mammals. Although this species is widely distributed throughout the world’s tropical and subtropical oceanic waters, like many deep-water species, it remains very poorly understood due to its mesopelagic distribution. We used a suite of biochemical tracers, including stable isotope analysis (SIA), fatty acid analysis (FAA), and environmental DNA (eDNA), to investigate the trophic ecology of this species in the Central Pacific around Hawaii. We found that large epipelagic prey constituted a relatively minor part of the overall diet. Surprisingly, small micronektonic and forage species (meso- and epipelagic) are the most important prey group for Cookiecutter sharks across the studied size range (17–43 cm total length), with larger mesopelagic species or species that exhibit diel vertical migration also being important prey. These results were consistent across all the tracer techniques employed. Our results indicate that Cookiecutter sharks play a unique role in pelagic food webs, feeding on prey ranging from the largest apex predators to small, low trophic level species, in particular those that overlap with the depth distribution of the sharks throughout the diel cycle. We also found evidence of a potential shift in diet and/or habitat with size and season. Environmental DNA metabarcoding revealed new prey items for Cookiecutter sharks while also demonstrating that eDNA can be used to identify recent prey in stomachs frozen for extended periods. Integrating across chemical tracers is a powerful tool for investigating the ecology of elusive and difficult to study species, such as meso- and bathypelagic chondrichthyans, and can increase the amount of information gained from small sample sizes. Better resolving the foraging ecology of these mesopelagic predators is critical for effective conservation and management of these taxa and ecosystems, which are intrinsically vulnerable to overfishing and exploitation.

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