Feeding ecology of 0-group sea bass, Dicentrarchus labrax, in salt marshesof Mont Saint Michel Bay (France)

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) dur ing flood and return to coastal waters during ebb. Most arrived with empty stomachs (33%), and feed actively during their short stay in the creeks (fr om 1 to 2 h) where they consumed on average a minimum of 8% of their body w eight. During flood tide, diet was dominated by mysids, Neomysis integer, w hich feed on marsh detritus. During ebb, when young sea bass left tidal mar sh creeks, the majority had full stomachs (more than 98%) and diet was domi nated by the most abundant marsh (including vegetated tidal flats and assoc iated 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 inte rtidal salt marshes play a fundamental role in the feeding of 0-group sea b ass. This suggests that the well known nursery function of estuarine system s, which is usually restricted to subtidal and intertidal flats, ought to b e extended to the supratidal, vegetated marshes and mainly to intertidal ma rsh creeks.