Effects of the feeding behavior of Crassostrea gigas (Bivalve Molluscs) on biosedimentation of natural particulate matter

Abstract

Some of the particulate matter found in bottom sediment comes from material rejected as pseudofaeces or produces as faeces by Crassostrea gigas . The amount of pseudofaeces rejected is proportional to the amount of seston for total seston values up to 4 .6 mg 1 -' . For this values up to pseudofaeces production, the amount of faeces is mainly limitated by pseudofaeces production and reaches a constant mean value of 8 .9 mg 1 -' g DW -' when seston concentration increases .The proportion of faeces versus pseudofaeces is over 1 when seston concentrations are below 10 mg 1 -', and remains less than 1 when seston concentrations are higher than 10 mg l -' .The pseudofaeces show a lower organic content (13 ± 3 %) than the material trapped through the gills (27 ± 4%), as well as a lower percentage of proteins and lipids, suggesting a selection by the labial palps . On the contrary, an enrichment with labile carbohydrates is recorded in pseudofaeces, probably due to mucus agglutination of rejected particulate matter .The feeding of Crassostrea gigas can package and transform (agglutinate, change the organic content, change the biochemical composition) suspended matter, thus influencing both the quality and quantity of organic matter sedimentation .

Influence of shellfish farming activities on the biogeochemical composition of the water column in Thau lagoon

“…This shift in growth rate is not significant during summer, because the effect of increasing temperature, which is much more important, tends to override the influence of shellfish farming zones. The particulate matter filtered by filter feeders can be recycled in underlying sediments after biodeposition (Deslous-Paoli et al 1992) and directly through excretion (Bayne & Scullard 1977). The enrichment of surface waters in the vicinity of shellfish farms with NH 4 + , SRP and Si illustrates this heterotrophic component induced by bivalves in their ecosystem (Prins & Smaal 1994).…”

Functional descriptions of feeding and energetics of the Pacific oyster Crassostrea gigas in New Zealand

“…Thompson & Bayne 1974, Epifanio & Edwart 1977, Crisp et al 1985, Deslous-Paoli et al 1992. This is partly due to the saturating nature of the FR as discussed above, but is also a consequence of increasing S resulting only in greater pseudofaeces production (see Foster-Smith 1975, Barillé et al 1997).…”

“…However, there is abundant evidence (e.g. Bayne & Hawkins 1990, Deslous-Paoli et al 1992, Iglesias et al 1992, Barillé et al 1997) that there is selection of organic material in preference to inorganic material at the palps. The sorting of organic material is efficient at low S and inefficient or non-existent at high S (e.g.…”

Numerical analysis of the food web of an intertidal mudflat ecosystem on the Atlantic coast of France

“…Particle uptake and release as pseudo-faeces only slightly alters the particle composition, so that particles remain available to the other components of the ecosystem (Feuillet-Girard et al 1994). The released fraction of consumed energy comprises between 62 and 92% , 1992, Soletchnick et al 1996, of which 50 to 90% are pseudo-faeces (Deslous-Paoli et al 1992, Soletchnik et al 1993). However, these particles can enrich benthic exchanges in comparison to the pelagic ones.…”

“…An inverse analysis computed with this data showed that an inclusion of the pseudo-faeces production obscures most of the other processes. Moreover, suspension feeders use pseudofaeces to enrich the organic fraction of their diet (Deslous-Paoli et al 1992, Iglesias et al 1992, Bayne et al 1993, Barillé et al 1997) and suspension feeding is a 'highly selective' process (Shumway et al 1985, Graf & Rosenberg 1997. For example, Crassostrea gigas feeds selectively upon the microphytobenthic food supply (Cognie et al 2001) and the pearl oyster Pinctada margaritifera selects its prey on both size and taxonomic criteria (Loret et al 2000).…”