Feeding habits and trophic level of sea bass ( Dicentrarchus labrax ) in the Messolonghi-Etoliko lagoons complex (Western Greece)

Abstract

Information on the quality and quantity of consumed food by fish is important for the classic ecological theory, mainly in identifying omnivory, feeding competition, assessing predator-prey functional responses and structure as well as the stability of food webs (Gerking, 1994). Diet composition data are also used for the estimation of trophic levels. The trophic level expresses the relative position of an animal in the food webs that nourish them ranging, for marine animals, between 2 (herbivores / detritivores) and 5.5 (specialised predators such as marine mammals) (Pauly et al., 2000). The estimation of trophic level allows the development of new approaches to the analysis of marine food webs and thereby it is essential for the management of fisheries resources as well as for quantifying the effects of fishing on the ecosystem (Pauly et al., 2000; Stergiou & Karpouzi, 2002). Coastal lagoons and estuaries play an important role as nurseries, offering food and shelter for the larval, juvenile and adult stages of numerous fish species that spawn in the open sea (Costa et al., 2002). The improvement of aquatic lagoon environments is among the aims of the EU Directive 2000/60/EC (Water Framework Directive, WFD), which defines qualitative, quantitative and ecological objectives aiming at the protection of these highly valuable ecosystems (Elliott & McLusky, 2002). Feeding habits and trophic level of sea bass (Dicentrarchus labrax) in the Messolonghi-Etoliko lagoons complex (Western Greece)