Feeding Ecology of 0-Group Sea Bass, Dicentrarchus labrax, in Salt Marshes of Mont Saint Michel Bay (France)

Abstract

0-group sea bass, Dicentrarchus labrax, colonize intertidal marsh creeks of Mont Saint Michel Bay, France, on spring tides (e.g., 43% of the tides) during flood and return to coastal waters during ebb. Most arrived with empty stomachs (33%), and feed actively during their short stay in the creeks (from 1 to 2 h) where they consumed on average a minimum of 8% of their body weight. During flood tide, diet was dominated by mysids, Neomysis integer, which feed on marsh detritus. During ebb, when young sea bass left tidal marsh creeks, the majority had full stomachs (more than 98%) and diet was dominated by the most abundant marsh (including vegetated tidal flats and associated marsh creeks) resident amphipod, Orchestia gammarellus. Temporal and tidal effects on diet composition were shown to be insignificant. Foraging in vegetated flats occurs very rarely since they are only flooded by about 5% of the tides. It was shown that primary and secondary production of intertidal salt marshes play a fundamental role in the feeding of 0-group sea bass. This suggests that the well known nursery function of estuarine systems, which is usually restricted to subtidal and intertidal flats, ought to be extended to the supratidal, vegetated marshes and mainly to intertidal marsh creeks.

Does the invasive plant Elymus athericus modify fish diet in tidal salt marshes?

“…Since the introduction of the outwelling concept (Odum, 1968), which states that tidal events export detrital organic matter produced in salt marshes to marine waters, strong evidence has also indicated that the export of organic matter from terrestrial to aquatic systems supports secondary production (Loneragan et al, 1997;Kurata et al, 2001). Consequently, salt marshes generally have a very high conservation value, directly as a result of their species complement and because of their role as a feeding ground for migrant birds (Norris et al, 1997;Lefeuvre et al, 2000), and fish, especially juveniles (Boesch and Turner, 1984;Laffaille et al, 2001Laffaille et al, , 2002.…”

“…During high tide, young sea bass (Dicentrarchus labrax L.) and sand gobies (Pomatoschistus minutus Pallas) exploit salt marsh production by feeding on resident invertebrates, mainly Orchestia gammarella (Laffaille et al, 1999(Laffaille et al, , 2001. Pomatoschistus minutus is among the most abundant fish species of coastal waters of western Europe (Costa and Cabral, 1999), and occurs frequently at high densities in a large European intertidal salt marsh (Laffaille et al, 2000a;Salgado et al, 2004).…”

“…The sand goby is an important prey for fish-eating vertebrates (Moreira et al, 1992;Hamerlynck and Cattrijsse, 1994). Dicentrarchus labrax is one of the most abundant commercial species of the Atlantic coast and in the Mont-Saint-Michel Bay (Laffaille et al, 2000a), where young fish, especially young of the year (0C), exploit tidal salt marshes (Laffaille et al, 2001). …”

Difference in responses of two coastal species to fluctuating salinities and temperatures: Potential modification of specific distribution areas in the context of global change

“…The top piscivorous predator (Kottelat, 2008), it exploits both coastal and shallow waters (Pickett and Pawson, 1996;Sanchez Vazquez and Munoz-Cueto, 2014) and for this reason is usually described as euryhaline fish species. Each year, young seabass colonise supratidal and intertidal marsh creeks and subtidal and intertidal flats to feed (Laffaille et al, 2001a). Grey mullets, although less abundant in estuaries (Nicolas et al, 2010), also have a key role and are described as marine seasonal migrants.…”

“…about 6 h), which is a common pattern for thicklip mullet (Chelon labrosus) and European seabass (Dicentrarchus labrax ) individuals in northwestern European coastal actchements (Laffaille et al, 2001a). The variability in responses of both fish species' metabolism to short-term salinity variations at different temperatures was compared.…”