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.

SARA' G, SARA' R (2007). Ontogenetic shift in feeding habits and trophic levels of bluefin tuna (Thunnus thynnus) in Mediterranean. JOURNAL OF APPLIED ICHTHYOLOGY, 23, 122-127 [10.1111/j.1439-0426.2006.00829.x].

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

SARA', Gianluca;
2007-01-01

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.
2007
Settore BIO/07 - Ecologia
SARA' G, SARA' R (2007). Ontogenetic shift in feeding habits and trophic levels of bluefin tuna (Thunnus thynnus) in Mediterranean. JOURNAL OF APPLIED ICHTHYOLOGY, 23, 122-127 [10.1111/j.1439-0426.2006.00829.x].
File in questo prodotto:
File Dimensione Formato  
Sarà-and-Sarà-2007-J.-Applied-Ichthyology.pdf

Solo gestori archvio

Dimensione 230.24 kB
Formato Adobe PDF
230.24 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/3238
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 80
  • ???jsp.display-item.citation.isi??? 78
social impact