<i>In Vivo</i> Studies of Suspension-Feeding Processes in the Eastern Oyster, <i>Crassostrea virginica</i> (Gmelin)

Ward, J. Evan; Newell, R. I. E.; Thompson, R. J.; MacDonald, Bruce A.

doi:10.2307/1542056

Cited by 102 publications

(62 citation statements)

References 36 publications

(48 reference statements)

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“…As reported for mucusbound food material (Ward et al, 1993;Ward et al, 1994), aggregates are likely broken down by the action of cilia on the gills and labial palps and the constituent particles ingested. Some aggregated material is likely to be rejected as pseudofeces, but our results demonstrate that a large fraction is ingested.…”

Section: Discussionmentioning

confidence: 79%

Marine aggregates facilitate ingestion of nanoparticles by suspension-feeding bivalves

Ward

Kach

2009

Marine Environmental Research

427

252

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As the application of nanomaterials to science and technology grows, the need to understand any ecotoxicological effects becomes increasingly important. Recent studies on a few species of fishes and invertebrates have provided data which suggest that harmful effects are possible. The way in which nanoparticles are taken up by aquatic organisms, however, has been little studied. We examined uptake of nanoparticles by two species of suspension-feeding bivalves (mussels, Mytilus edulis; oysters, Crassostrea virginica), which capture individual particles < 1 μm with a retention efficiency of < 15%. Given this limitation, it would appear that nanoparticles could not be ingested in large numbers. During certain times of the year, however, > 70% of suspended particles are incorporated within aggregates that are > 100 μm in size. Therefore, we delivered bivalves fluorescently labeled, 100-nm polystyrene beads that were either (1) dispersed or (2) embedded within aggregates generated in the laboratory. Results indicate that aggregates significantly enhance the uptake of 100-nm particles. Nanoparticles had a longer gut retention time than 10-μm polystyrene beads suggesting that nanoparticles were transported to the digestive gland. Our data suggest a mechanism for significant nanoparticle ingestion, and have implications for toxicological effects and transfer of nanomaterials to higher trophic levels.

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Section: Discussionmentioning

confidence: 79%

Marine aggregates facilitate ingestion of nanoparticles by suspension-feeding bivalves

Ward

Kach

2009

Marine Environmental Research

427

252

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“…Bivalves also expel mucus and pseudofeces from the inhalant siphon or aperture during rapid valve adductions. Pseudofeces are produced by the gills and labial palps, and are composed of mucopolysaccharides and uningested particles (Ward et al 1994, Urrutia et al 2001. They have been shown to significantly increase aggregation and sedimentation of suspended particulates to the benthos (Davies & Hawkins 1998), an effect that could also be attributed to the presence of TEP.…”

Section: Introductionmentioning

confidence: 99%

Production of transparent exopolymer particles (TEP) by the eastern oyster Crassostrea virginica

McKee¹,

Ward²,

MacDonald³

et al. 2005

Mar. Ecol. Prog. Ser.

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Transparent exopolymer particles (TEP) play an important role in aggregation, phytoplankton bloom dynamics and the fate of organic carbon. Various types of plankton are known to release exopolymers that contribute to the TEP pool. Little is known, however, about other potential sources of TEP and TEP precursors in the oceans, especially in nearshore waters. Suspension-feeding bivalves can form dense assemblages in coastal waters and can process large volumes of water during feeding activities (e.g. 5 l h -1 g -1 dry wt). They secrete mucus to maintain clean body surfaces and to aid in capturing and transporting food material. We hypothesized that mucopolysaccharides, which are released from bivalves in dissolved or particulate form, contribute to the TEP pool. To test this hypothesis, laboratory experiments were carried out to measure the concentration of TEP and DOC in chambers with actively feeding oysters Crassostrea virginica over a 9 h period. Field experiments were conducted to measure TEP and DOC production by oysters in situ, using clear Plexiglas chambers on an intertidal sand-flat in New Brunswick, Canada. TEP concentrations were determined with an Alcian blue staining technique and spectrophotometric detection. DOC concentrations were determined using high-temperature catalytic oxidation (HTCO) with a platinum catalyst. Laboratory results indicated that oysters significantly enhanced TEP and DOC concentrations compared to control levels over 9 h. Likewise, field experiments demonstrated elevated TEP concentrations in experimental chambers compared to control treatments. Our results support the hypothesis that oysters contribute to the production of TEP in coastal marine ecosystems.

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“…To date, the gills have been the quasi-exclusive objects of such studies; a notable exception is the labial palps of Crassostrea virginica, for which video-endoscopic data are available (Ward et al 1994). In addition to the gills, several other organs play important roles in particle handling: labial palps, lips and mantle (Kellogg 1915, Bernard 1974, Foster-Smith 1975, 1978, Kierrboe & Merhlenberg 1981, Theisen 1982, Newel1 & Jordan 1983, Shumway et al 1985; a complete understanding of the mechanisms of particle processing in bivalves must therefore include investigations of these organs.…”

Section: Introductionmentioning

confidence: 99%

Particle processing on the labial palps of Mytilus edulis and Placopecten magellanicus (Mollusca:Bivalvia)

Pg¹,

Sd²

1997

Mar. Ecol. Prog. Ser.

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In order to understand particle processing on the labial palps of suspension-feeding bivalves, mucocyte mapping and visual observations were performed on adult Mytilus edulis (Fam. Mytihdae) and Placopecten magellanjcus (Fam. Pectinidae] Mucocyte contents were divided into categories depending on staining affinity for periodic acid-Schiff and alcian blue. The mucocyte distr~bu-tion was determined by counts at representative sites on the palps, done on stained whole mounts or histological sections. Functional correlates for M. edulis were obtained using video endoscopy; this technique was compared to observations of carmine particle transport on specimens from which 1 valve had been removed. Video endoscopy was precluded in P. magellanicus due to the large and extremely sensitive arborescent lips; the behaviour of carmine particles deposited on the palps was therefore observed for this species. Mucus-particle cords are removed from the gill ventral partlcle groove by the cilia of the dorsal fold of the M. edulis palp at right angles to the current flow; highviscosity acid (AMPS) and acid-dominant (ADMPS)-containing mucocytes probably stabilize the cord at this point. The position of the retractable dorsal fold determines whether the cords are rejected or processed for ingestion. When the specimen's ingestlve capacity is overloaded, the arriving cords are transported parallel to and upon the palp crests to the palp ventral margin, and then to the posteriormost tip of the palp for rejection. This rejection pathway is characterized by transport perpendicular to or counter to current flow and high proportions of AMPS mucocytes. When the ingestive capacity of the specimen is not exceeded, mucus-particle cords are directed into the palp particle groove, where they are transformed into a slurry by the mechanical action of the palp crests and dorsal fold, and probably also the addition of low-viscosity neutral mucopolysacchandes present on the palp crests. The resulting slurry is amenable to both ingestion and particle selection; selected particles continue their anteriorward movement in the palp particle groove, while rejected particles are transported ventrally in the AMPS-rich crest troughs to join the rejection pathway along the palp ventral margin. The palp rejection site for P rnagellanicus is also the AMPS-rich ventro-posterior margin, which terminates in a mixed mucopolysaccharide (MMPS)-rich reflected tip, probably related to the valve-clapping voidance of pseudofeces. Both the oral groove and the crest summits contain almost exclusively MMPS, suggesting that in this species the labial palps are mostly Involved in ingestive particle handling, as opposed to M . edulis. Differences in gill structure and functlon may account for thls putative difference in palp function. The combination of mucocyte mapping and video endoscopy (where possible) significantly enhances our understanding of bivalve feeding mechanisms.

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In Vivo Studies of Suspension-Feeding Processes in the Eastern Oyster, Crassostrea virginica (Gmelin)

Cited by 102 publications

References 36 publications

Marine aggregates facilitate ingestion of nanoparticles by suspension-feeding bivalves

Marine aggregates facilitate ingestion of nanoparticles by suspension-feeding bivalves

Production of transparent exopolymer particles (TEP) by the eastern oyster Crassostrea virginica

Particle processing on the labial palps of Mytilus edulis and Placopecten magellanicus (Mollusca:Bivalvia)

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