Trophic characterization of the Prévost lagoon (Mediterranean Sea) by the feeding habits of the European eel Anguilla anguilla
- Authors:
-
BOUCHEREAU Jean-Luc,
MARQUES Catarina,
PEREIRA Patricia,
GUELORGET Olivier,
VERGNE Yvan
- Keywords:
-
lagoonal systems;
opportunism;
bioindicator;
mediterranean;
anguilla anguilla;
diet
- Abstract:
- This study deals with temporal variations in eel diet Anguilla anguilla sampled at each of the four seasons in the
Languedocian Prévost lagoon (Gulf of Lion) from Autumn 1998 to Summer 1999. The following feeding indices were
calculated based on observations of 12 categories of prey found in the contents of full stomachs: coefficient of vacuity CV,
degree of fullness DR, occurrence frequency PP, relative abundance N (in %) and relative weight P (in %). The interpreta-
tion of results is also based on the Costello's method (1990) which combines PP and N. Anguilla anguilla mainly feeds on
benthic organisms, primarily Gammarus gr. locusta, Polychaeta, insect larvae, small fish. Based on variations in eel diet,
seasonal influence is illustrated by a decrease in feeding activity in summer which gradually increases during the following
seasons. The good trophic quality available to eels in the Prévost lagoon depends on its hydrodynamics which is directly
related to the movement of water entering and leaving lagoon by a short communication with the sea. This water move-
ment accelerates the enrichment and production processes of this ecosystem. Changes observed during the four seasons
illustrate an opportunistic type of feeding behaviour. Eels consume the most available benthic prey. They favour the impor-
tance of the prey at a given moment without using a particular feeding strategy like specialisation or generalisation. Thus,
eel adapts its diet in adjusting available energy resources in the ecosystem. Because of this, the lagoon-resident species
Anguilla anguilla is an obvious indirect bioindicator of the trophic capacity and present level of confinement in the brackish
water lagoon ecosystem of Prévost.
- Résumé :
- Caractérisation trophique de la lagune du Prévost (Méditerranée) par l'étude du régime alimentaire de l'anguille
européenne Anguilla anguilla. Cette étude traite des variations temporelles du régime alimentaire des anguilles Anguilla
anguilla vivant dans la lagune languedocienne du Prévost (Golfe du Lion), et échantillonnées aux quatre saisons de l'au-
tomne 1998 à l'été 1999. Les indices alimentaires suivants sont calculés à partir de l'observation de 12 catégories de proies
dans les contenus d'estomacs remplis: coefficient de vacuité CV, degré de remplissage DR, pourcentages de présence PP,
numérique N et pondéral P. L'interprétation des résultats est aussi fondée sur la méthode de Costello (1990) qui conjugue
PP et N. Anguilla anguilla se nourrit principalement d'organismes benthiques, essentiellement des Gammarus gr. locusta,
Polychètes, larves d'Insectes, petits poissons. D'après les variations du régime alimentaire de l'anguille, l'influence saison-
nière se manifeste par une diminution de l'activité nutritionnelle en été qui s'inverse et augmente au fur et à mesure des
saisons suivantes. La grande qualité trophique offerte aux anguilles par la lagune du Prévost dépend de son hydrody-
Cah. Biol. Mar. (2006) 47 : 133-142
Reçu le 16 septembre 2005 ; accepté après révision le 4 janvier 2006.
Received 16 September 2005; accepted in revised form 4 January 2006.
Introduction
Although the lagoons along the western French
Mediterranean coast have the same origin regarding their
formation (Guelorget & Perthuisot, 1983 & 1992), each has
its own geomorphologic characteristics with regards to sur-
face area, depth, inputs of fresh or marine water, catchment
area and the nature of sediment. These have an influence on
some environmental factors, such as salinity, temperature,
water renewal which in turn depend on climatic conditions.
Fluctuations in these factors during the various seasons
bring about significant variability in biological populations
present and consequently in fish populations (B
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