Sources de carbone et d'acides gras essentiels pour les juvéniles de Liza saliens (Pisces, Mugilidae) dans le réseau trophique d'une lagune côtière méditerranéenne : approches in situ par biomarqueurs lipidiques et isotopiques

Abstract : Mediterranean coastal lagoons are considered as major nursery areas for several coastal fish species. In Vassova lagoon (Kavala Prefecture, Greece), this continuous input of juveniles, along with the lagoons’ naturalfood resources, sustain local extensive aquaculture. Therefore, in order to optimise the fisheries’ yield, thefactors affecting juveniles’ growth and survival in the lagoon need to be assessed. The objectives of this research work are to identify the organic matter sources sustaining growth of a common commercial Mediterranean species (Liza saliens, Mugilidae) juveniles’ (15 – 50 mm, total length / TL) and to assess their nutritional quality in terms of polyunsaturated fatty acids (PUFAs). In that aim, fish (L.saliens juveniles and principal resident fish species), their potential preys, and basal organic matter sources where sampled monthly during L. saliens settlement in Vassova lagoon (June - November). The origin of carbon assimilated by L. saliens was assessed using lipid and isotopic biomarker approaches as well as stomach content analysis. Moreover, lipid analyses allowed understanding the influence of diet on the fatty acid (FA) composition of L. saliens storage (neutral lipids : NLs) and membrane lipids (polar lipids: PLs) during early life in the lagoon. Finally, the isotopic composition of the PUFAs assimilated by L. saliens juveniles was determined by GC-C-IRMS and allowed the assessment of the sources of these compounds in the ecosystem. Results indicate that at their arrival at the lagoons’ mouth L. saliens juveniles (~15 mm, TL) feed on planktonic organisms. When juveniles reach the size of 20 mm (TL), they progressively shift towards benthic prey. This dietary shift is followed by an important decrease of the dietary levels of DHA. Indeed, in Vassova lagoon, this PUFA seems to be mainly produced by planktonic microorganisms. Therefore, during the transition from the marine planktonic environment towards the lagoons’ demersal habitat, L. saliens juveniles probably experience a decrease in the nutritional quality of their food. However, 22:6ω3 as well as 20:4ω6 appear to be actively retained in L.saliens membrane lipids (PLs). More interestingly, 20:4ω6 seems also to be retained by other fish species found in the lagoon. The latter suggests that this essential compound, which in fish is implicated in resistance processes to environmental stressors, has an important physiological role for fish in estuarine environments.
Document type :
Theses
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00600250
Contributor : Abes Star <>
Submitted on : Tuesday, June 14, 2011 - 1:08:08 PM
Last modification on : Friday, August 23, 2019 - 3:50:04 PM
Long-term archiving on : Sunday, December 4, 2016 - 5:13:42 PM

File

Koussoroplis-A-2010.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-00600250, version 1

Collections

Citation

Apostolos-Manuel Koussoroplis. Sources de carbone et d'acides gras essentiels pour les juvéniles de Liza saliens (Pisces, Mugilidae) dans le réseau trophique d'une lagune côtière méditerranéenne : approches in situ par biomarqueurs lipidiques et isotopiques. Sciences agricoles. Université Blaise Pascal - Clermont-Ferrand II, 2010. Français. ⟨NNT : 2010CLF22055⟩. ⟨tel-00600250⟩

Share

Metrics

Record views

669

Files downloads

1357