Feeding habits of juvenile yellowfin tuna ( Thunnus albacares ) in Ecuadorian waters assessed from stomach content and stable isotope analysis

Abstract Kajikia audax, Thunnus albacares, Katsuwonus pelamis, and Auxis spp. occupy high and middle-level trophic positions in the food web. They represent important sources for fisheries in Ecuador. Despite their ecological and economic importance, studies on pelagic species in Ecuador are scarce. This study uses stable isotope analysis to assess the trophic ecology of these species, and to determine the contribution of prey to the predator tissue. Isotope data was used to test the hypothesis that medium-sized pelagic fish species have higher δ15N values than those of the prey they consumed, and that there is no overlap between their δ13C and δ15N values. Results showed higher δ15N values for K. audax, followed by T. albacares, Auxis spp. and K. pelamis, which indicates that the highest position in this food web is occupied by K. audax. The stable isotope Bayesian ellipses demonstrated that on a long time-scale, these species do not compete for food sources. Moreover, δ15N values were different between species and they decreased with a decrease in predator size.

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Use of epidermal mucus in elasmobranch stable isotope studies: a pilot study using the giant manta ray (Manta birostris)

Marine and Freshwater Research ◽

10.1071/mf16355 ◽

2018 ◽

Vol 69 (2) ◽

pp. 336 ◽

Cited By ~ 6

Author(s):

K. B. Burgess ◽

M. Guerrero ◽

A. J. Richardson ◽

M. B. Bennett ◽

A. D. Marshall

Keyword(s):

Stable Isotope ◽

Stable Isotope Analysis ◽

Time Course ◽

Feeding Habits ◽

Isotope Analysis ◽

Δ13c Values ◽

Significant Difference ◽

Manta Birostris ◽

Epidermal Mucus ◽

Manta Ray

Stable isotope analysis of tissues with different turnover rates allows for a broader temporal view of a species’ feeding habits. Epidermal mucus is a rapid to medium turnover ‘tissue’ in teleost fish, but its use in elasmobranch dietary studies is unknown. In the present study, we conducted stable isotope analysis on mucus and muscle from the giant manta ray Manta birostris. Mucus δ13C values were depleted and closer to surface zooplankton δ13C values compared with muscle, whereas there was no significant difference in δ15N values between these two tissue types. Using diet tissue discrimination factors from the literature, there was no significant difference in the expected prey profile between muscle and epidermal mucus. However, a broader range in δ13C values of expected prey was shown for mucus compared with muscle. The results suggest that if M. birostris mucus is indicative of recent dietary intake, resource use during aggregative behaviour off Ecuador is broader, but with no obvious resource switching. The present study is the first example of using bulk stable isotope analysis to evaluate mucus to investigate feeding ecology in elasmobranchs. However, the time course for the change in mucus isotope signature still needs to be determined through controlled feeding studies in an aquarium setting.

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Feeding habits and ecological role of the freshwater stingray Potamotrygon magdalenae (Duméril 1865) (Myliobatiformes: Potamotrygonidae), combining gut-content and stable isotope analysis

Environmental Biology of Fishes ◽

10.1007/s10641-019-00897-0 ◽

2019 ◽

Vol 102 (8) ◽

pp. 1119-1136

Author(s):

Viviana Márquez-Velásquez ◽

Ricardo S. Rosa ◽

Esteban Galindo ◽

Andrés F. Navia

Keyword(s):

Stable Isotope ◽

Stable Isotope Analysis ◽

Feeding Habits ◽

Isotope Analysis ◽

Ecological Role ◽

Gut Content ◽

Freshwater Stingray

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Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis

ICES Journal of Marine Science ◽

10.1093/icesjms/fss125 ◽

2012 ◽

Vol 69 (7) ◽

pp. 1277-1288 ◽

Cited By ~ 16

Author(s):

Hildur Petursdottir ◽

Stig Falk-Petersen ◽

Astthor Gislason

Keyword(s):

Fatty Acid ◽

Stable Isotope ◽

Stable Isotope Analysis ◽

Trophic Interactions ◽

Trophic Ecology ◽

Feeding Habits ◽

Isotope Analysis ◽

Trophic Levels ◽

Amphipod Species ◽

Blue Whiting

Abstract Petursdottir, H., Falk-Petersen, S., and Gislason, A. 2012. Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis. – ICES Journal of Marine Science, 69: . A trophic study was carried out in August of 2007 and 2008 on the pelagic ecosystem in the Subarctic Iceland Sea. Carbon and nitrogen stable isotopes and fatty acid biomarkers were used to study trophic linkages and the trophic ecology of the most important pelagic species in this ecosystem, with emphasis on capelin (Mallotus villosus). According to 15N enrichment results, there are 3–4 trophic levels in this ecosystem excluding organisms of the microbial loop and birds and mammals. The primarily herbivorous copepod Calanus hyperboreus occupies the lowest trophic level of the animal species studied, and adult capelin and blue whiting (Micromesistius poutassou) occupy the highest level. Calanus spp. proved to be an important dietary component of most of the species studied, the euphausiid species Thysanoessa inermis and T. longicaudata being exceptions. The chaetognath Eukrohnia hamata is a pure carnivore, feeding heavily on Calanus spp., whereas most of the other zooplankton species studied practice an omnivorous–carnivorous feeding mode. The amphipod species Themisto libellula is important in the diet of adult capelin. Adult capelin and blue whiting share the same feeding habits and could therefore be competing for food.

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Feeding Ecology of Juvenile Yellowfin Tuna from Waters Southwest of Taiwan Inferred from Stomach Contents and Stable Isotope Analysis

Marine and Coastal Fisheries ◽

10.1080/19425120.2015.1094157 ◽

2015 ◽

Vol 7 (1) ◽

pp. 537-548 ◽

Cited By ~ 11

Author(s):

Jinn-Shing Weng ◽

Ming-An Lee ◽

Kwang-Ming Liu ◽

Ming-Shu Hsu ◽

Mine-Kune Hung ◽

...

Keyword(s):

Stable Isotope ◽

Stable Isotope Analysis ◽

Feeding Ecology ◽

Isotope Analysis ◽

Stomach Contents ◽

Yellowfin Tuna

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Feeding habits and trophic level of the shovelnose guitarfish (Pseudobatos productus) in the upper Gulf of California

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315417000832 ◽

2017 ◽

Vol 98 (7) ◽

pp. 1783-1792 ◽

Cited By ~ 4

Author(s):

Fausto Valenzuela-Quiñonez ◽

Felipe Galván-Magaña ◽

David A. Ebert ◽

E. Alberto Aragón-Noriega

Keyword(s):

Stable Isotope ◽

Stomach Content ◽

Gulf Of California ◽

Feeding Habits ◽

Isotope Analysis ◽

Trophic Relationships ◽

Generalist Predators ◽

Class Iii ◽

Ontogenetic Changes ◽

Diet Shifts

The shovelnose guitarfish (Pseudobatos productus) is the most abundant and economically important batoid in Gulf of California fisheries. Despite the importance of the guitarfish in the demersal ecosystem, its trophic relationships are poorly understood. Results from stomach content and stable isotope analysis indicate P. productus is a specialist predator that feeds on coastal benthic organisms, mainly crustaceans, followed by fishes and cephalopods in the Upper Gulf of California. Males and females did not differ in dietary composition and isotopic values. Pseudobatos productus displayed ontogenetic changes in the diet, with smaller, immature individuals having a more specialized diet and mature individuals becoming generalist predators. Size classes I (<570 mm) and II (>570 mm) fed almost exclusively on crustaceans (99.78% and 82.37 %IRI, respectively). Size class III (>832 mm) increased consumption of fishes (22.11 %IRI) and squid (6.54 %IRI). Ontogenetic diet shifts were strongly supported by the SIAR mixing model. Stomach content and stable isotope analyses classify P. productus as a second-order predator.

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