Role of fish communities in particulate organic matter fluxes between salt marshes and coastal marine waters in the Mont Saint-Michel Bay

Abstract

Among the 90 fishspecies censused in the Mont Saint-Michel Bay (France), 23 colonise and forage in the salt marshes during flood. Therefore, this environment may play an important trophic and nursery role for these species. This community is largely dominated by mullets (81% of the biomass), Liza ramada and secondarily L. aurata. But gobies (mainly Pomatoschistus minutus and P. lozanoï) and sea bass (Dicentrarchus labrax) are also present; they represent respectively 11% and 4% of the biomass. During the tide cycles, mullets export from salt marshes about 7% of their body weight (FW) containing a mixture of sediment (43%), organic matter (24%) and water (33%). Gobies and sea bass mainly feed on dwelling macro-invertebrates, and they export respectively 4.5% and 10% of their body weight during a tide cycle. Thus, we estimated that 50 tonnes year −1 of particulate organic matter (dry weight POM) are exported from the 4000 ha of salt marshes to the marine coastal waters. These fish communities appear to be POM transporters and could play a significant role in the global energy budgets of coastal environments such as Mont Saint-Michel Bay. According to the seasons and the years, the energy exported by fish communities is assumed to range between 0 and 10% of the total POM output.

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

“…In fact, only a few fish species are able to assimilate salt marsh primary production directly or indirectly; this is the case for mullets Liza and Mugil spp., sand gobies Pomatoschisus spp. and sea bass Dicentrarchus labrax in the MontSaint-Michel Bay (Laffaille et al, 1998(Laffaille et al, , 2002. Salt marsh primary production is essentially assimilated by many invertebrates, and especially by Orchestia gammarella and mysids in European salt marshes (Zagursky and Feller, 1985;Créach et al, 1997).…”

“…The rest of the time the salt marsh, including tidal creeks and vegetated tidal flats, is emerged. Thus, this complex is colonized by fish and marineeestuarine invertebrates such as mysids, amphipods and decapods only for very short periods (1e2 h) during the spring tides when the vegetated creeks and the vegetated intertidal surface are accessible (Laffaille et al, 1998(Laffaille et al, , 2000a. Other macro-invertebrates are semi-terrestrial (e.g.…”

“…Samplings were made during the evening ebb in order to analyse diet composition after residence in salt marsh creeks (Laffaille et al, 1999(Laffaille et al, , 2001). Samplings were conducted using 4 mm mesh fyke nets set across the creek (see Laffaille et al, 1998). All samples were stored immediately in a refrigerated box (about 0 C) in salt marsh and in a deep freezer (ÿ18 C) at the laboratory until examination of the gut contents.…”

Reproductive Biology of Keeled Fish <i>Liza Carinata</i> (Valenciennes, 1836) from Suez Bay, Egypt

“…Liza carinata commonly inhabit tropical and warm-temperate estuaries (McDowall, 1988;Blaber, 1997;Pombo et al, 2005). Laffaille et al, 1998;Laffaille et al, 2002;Torras et al, 2000;Cardona, 2001;and Almeida, 2003 indicated that mugilidae play a crucial ecological role where this fish community appears to be particulate organic matter transporter and could play a significant role in the global energy budgets of environment. This fish are valuable food sources and ecologically important as primary consumer at coastal and estuarine food chains, and also very representative species for rearing in fish farms (El-Halfawy, 2004;Katsugawa et al, 2006).…”

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

“…Animal movement is an important ecological process that determines the spatial, demographic and genetic structure of populations (McCauley, 1995;Hanski and Gilpin, 1997;Wiens, 2000) and links levels within trophic and nutrient hierarchies through the transport of material (including biomass) (e.g. Deegan, 1993;Kneib, 1997b;Marguillier et al, 1997;Laffaille et al, 1998). Movement paths of individuals and populations reflect both ecological and evolutionary responses to environmental heterogeneity (Southwood, 1977;Levin et al, 1984;Cohen and Levin, 1991).…”