Experimental study of the filtration of clays by the oyster Crassostrea gigas (Thunberg): Adjustment of particle size for best retention

• Published in: Aquaculture Vol. 69; no. 3; pp. 355 - 366
• Main Authors: Sornin, J.M., Deslous-Paoli, J.M., Hesse, O.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.1988; Elsevier Science
• Subjects: Animal, plant and microbial ecology; Applied ecology; Aquaculture; Biological and medical sciences; Crassostrea gigas; Fundamental and applied biological sciences. Psychology; Marine; Poitou-Charente; Particle size; Filtration; Nutrition; Oyster farming; Europe; Experimental study; Ingestion; Digestive transit; Marine environment; Charente-Maritime; Bivalvia; France; Invertebrata; Mollusca; Crassostrea gigas
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/0044-8486(88)90342-0

Pure clay suspensions of kaolinite, montmorillonite and illite were mixed for filtration by the oyster Crassostrea gigas (Thunberg). During the experiment, the water temperature, salinity and organic content of the suspended matter were stable. Differences in total biodeposition (faeces plus pseudofaeces) depended on the size of the suspended particles. The suspension characterized by particles smaller than 2.5 μm (illite) was not efficiently retained. Aggregates larger than 5 μm (montmorillonite) were rejected as pseudofaeces without ingestion. The retention rate was stimulated by addding a suspension (kaolinite) which adjusts the mode of the particle size distribution to a value between 3 and 4 μm. This adjustment not only increased retention efficiency, as estimated by the ratio faeces + pseudofaeces available suspended matter , but also facilitated ingestion. The efficiency of ingestion of suspended particles, defined as the ratio pseudofaeces faeces , was not controlled by the oysters if the particles were too small or too large. Intestinal transit took one hour. Organic enrichment occurred in the total biodeposits (faeces + pseudofaeces), equivalent to a loss of energy of 0.98 J h −1 per gram of oyster dry tissue. No changes were observed by X-ray analysis or by scanning for clay minerals in the faeces.