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Particle selection, ingestion, and absorption in filter-feeding bivalves

1985; Elsevier BV; Volume: 91; Issue: 1-2 Linguagem: Inglês

10.1016/0022-0981(85)90222-9

1879-1697

Sandra E. Shumway, Terry L. Cucci, Richard Newell, Clarice M. Yentsch,

Wastewater Treatment and Nitrogen Removal

Measurements were made of the clearance rate of six bivalve species each in the presence of mixed cell suspensions of the dinoflagellate Prorocentrum minimum (Pavillard) Schiller (clone Exuv), the diatom Phaeodactylum tricornutum Bohlin (clone Phaeo), and the cryptomonad flagellate Chroomonas salina (Wislouch) Butcher (clone 3C). Use of flow cytometry allowed estimation not only of the clearance rate of individual cell types, but also of their proportional occurrence in the pseudofaeces and faeces. It has been recognized that at least three mechanisms of selecting suspended particles may be present in isolation or in combination. These are: (a) preferential clearance on the ctenidia: Ostrea edulis L., for example, preferentially clears the dinoflagellate Exuv compared with similar sized cells of the diatom Phaeo and the cryptomonad flagellate 3C; (b) preingestive selection on the labial palps: the diatom Phaeo was consistently and preferentially rejected in the pseudofaeces of Ensis directus Conrad, Placopecten magellanicus (Gmelin) and Arctica islandica (L.), (c) differential absorption in the gut i.e., post-ingestive selection: of the mixed diet which was ingested, there is clear evidence of a preferential absorption of the cryptomonad flagellate 3C in the majority of the bivalves from which we obtained faecal material. The possibility of selective removal of particular components of the available food resource, especially in the case of our experiments with the cryptomonad flagellate 3C, suggests that such organisms may be quantitatively more important in the diet of bivalves than their relative abundance under natural conditions might lead us to suppose. The ability of the oyster Ostrea edulis to selectively clear the dinoflagellate Exuv from mixed cell suspensions also may have important implications in our understanding of how toxic dinoflagellates may be concentrated on the ctenidia of commercially significant bivalves.