Ontogenetic shift in feeding habits and trophic levels of bluefin tuna (Thunnus thynnus) in Mediterranean

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Abstract

Possible changes in diet and trophic levels in relation to size of Mediterranean bluefin tuna, Thunnus thynnus, were investigated using labelled carbon (d13C) and nitrogen (d15N) stable isotopes. Samples were obtained from two locations in the southern Tyrrhenian Sea (Western Mediterranean Sea) in May and October 2004. The d13C and d15N analyses revealed at least three significant isotopic groups [small juveniles (0.7– 2.2 kg), sub-adults (15–50 kg) and adults (70 to 225 kg)]. d13C was negatively dependent on weight, while d15N was positively dependent on weight [TW ¼ 8.2 (±0.16) + 0.03 (± 0.0) *d15N (n ¼ 49; r ¼ 0.91; P < 0.001)]. Different prey contribution to the diet was highlighted for each class. The diet of juveniles comprised zooplankton, small pelagic fish and some coastal fish; sub-adults relied on medium pelagic fish, shrimps and cephalopods, and adults relied mainly on cephalopods and larger fish. The trophic level (TL) of tunas belonging to each size class was closely correlated to weight, starting from ca 3.0 TL for Group I and reaching 4.4–4.8 TL for the giants. Bluefin tuna, from small juveniles to giants, showed a shift in feeding preferences due to different use of habitats and food items as a function of the life stage.
Lingua originaleEnglish
pagine (da-a)122-127
Numero di pagine6
RivistaJournal of Applied Ichthyology
Volume23
Stato di pubblicazionePublished - 2007

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Thunnus thynnus
tuna
trophic level
pelagic fish
cephalopod
Cephalopoda
diet
Tyrrhenian Sea
feeding preferences
nitrogen isotope
fish
Mediterranean Sea
stable isotopes
zooplankton
stable isotope
shrimp
food
trophic levels
carbon
habitat

All Science Journal Classification (ASJC) codes

  • Aquatic Science

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@article{16b06b01c9824a47aeab747590511d3c,
title = "Ontogenetic shift in feeding habits and trophic levels of bluefin tuna (Thunnus thynnus) in Mediterranean",
abstract = "Possible changes in diet and trophic levels in relation to size of Mediterranean bluefin tuna, Thunnus thynnus, were investigated using labelled carbon (d13C) and nitrogen (d15N) stable isotopes. Samples were obtained from two locations in the southern Tyrrhenian Sea (Western Mediterranean Sea) in May and October 2004. The d13C and d15N analyses revealed at least three significant isotopic groups [small juveniles (0.7– 2.2 kg), sub-adults (15–50 kg) and adults (70 to 225 kg)]. d13C was negatively dependent on weight, while d15N was positively dependent on weight [TW ¼ 8.2 (±0.16) + 0.03 (± 0.0) *d15N (n ¼ 49; r ¼ 0.91; P < 0.001)]. Different prey contribution to the diet was highlighted for each class. The diet of juveniles comprised zooplankton, small pelagic fish and some coastal fish; sub-adults relied on medium pelagic fish, shrimps and cephalopods, and adults relied mainly on cephalopods and larger fish. The trophic level (TL) of tunas belonging to each size class was closely correlated to weight, starting from ca 3.0 TL for Group I and reaching 4.4–4.8 TL for the giants. Bluefin tuna, from small juveniles to giants, showed a shift in feeding preferences due to different use of habitats and food items as a function of the life stage.",
author = "Gianluca Sara' and Sar{\`a}",
year = "2007",
language = "English",
volume = "23",
pages = "122--127",
journal = "Journal of Applied Ichthyology",
issn = "0175-8659",
publisher = "Wiley-Blackwell",

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TY - JOUR

T1 - Ontogenetic shift in feeding habits and trophic levels of bluefin tuna (Thunnus thynnus) in Mediterranean

AU - Sara', Gianluca

AU - Sarà, null

PY - 2007

Y1 - 2007

N2 - Possible changes in diet and trophic levels in relation to size of Mediterranean bluefin tuna, Thunnus thynnus, were investigated using labelled carbon (d13C) and nitrogen (d15N) stable isotopes. Samples were obtained from two locations in the southern Tyrrhenian Sea (Western Mediterranean Sea) in May and October 2004. The d13C and d15N analyses revealed at least three significant isotopic groups [small juveniles (0.7– 2.2 kg), sub-adults (15–50 kg) and adults (70 to 225 kg)]. d13C was negatively dependent on weight, while d15N was positively dependent on weight [TW ¼ 8.2 (±0.16) + 0.03 (± 0.0) *d15N (n ¼ 49; r ¼ 0.91; P < 0.001)]. Different prey contribution to the diet was highlighted for each class. The diet of juveniles comprised zooplankton, small pelagic fish and some coastal fish; sub-adults relied on medium pelagic fish, shrimps and cephalopods, and adults relied mainly on cephalopods and larger fish. The trophic level (TL) of tunas belonging to each size class was closely correlated to weight, starting from ca 3.0 TL for Group I and reaching 4.4–4.8 TL for the giants. Bluefin tuna, from small juveniles to giants, showed a shift in feeding preferences due to different use of habitats and food items as a function of the life stage.

AB - Possible changes in diet and trophic levels in relation to size of Mediterranean bluefin tuna, Thunnus thynnus, were investigated using labelled carbon (d13C) and nitrogen (d15N) stable isotopes. Samples were obtained from two locations in the southern Tyrrhenian Sea (Western Mediterranean Sea) in May and October 2004. The d13C and d15N analyses revealed at least three significant isotopic groups [small juveniles (0.7– 2.2 kg), sub-adults (15–50 kg) and adults (70 to 225 kg)]. d13C was negatively dependent on weight, while d15N was positively dependent on weight [TW ¼ 8.2 (±0.16) + 0.03 (± 0.0) *d15N (n ¼ 49; r ¼ 0.91; P < 0.001)]. Different prey contribution to the diet was highlighted for each class. The diet of juveniles comprised zooplankton, small pelagic fish and some coastal fish; sub-adults relied on medium pelagic fish, shrimps and cephalopods, and adults relied mainly on cephalopods and larger fish. The trophic level (TL) of tunas belonging to each size class was closely correlated to weight, starting from ca 3.0 TL for Group I and reaching 4.4–4.8 TL for the giants. Bluefin tuna, from small juveniles to giants, showed a shift in feeding preferences due to different use of habitats and food items as a function of the life stage.

UR - http://hdl.handle.net/10447/3238

M3 - Article

VL - 23

SP - 122

EP - 127

JO - Journal of Applied Ichthyology

JF - Journal of Applied Ichthyology

SN - 0175-8659

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