Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas , Mytil
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ORIGINAL PAPER
Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas, Mytilus edulis and Cerastoderma edule, in relation to food competition Karin Troost Æ Eize J. Stamhuis Æ Luca A. van Duren Æ Wim J. Wolff
Received: 3 July 2008 / Accepted: 11 November 2008 / Published online: 2 December 2008 Ó The Author(s) 2008. This article is published with open access at Springerlink.com
Abstract Introduced Pacific oysters (Crassostrea gigas) have shown rapid expansion in the Oosterschelde estuary, while stocks of native bivalves declined slightly or remained stable. This indicates that they might have an advantage over native bivalve filter feeders. Hence, at the scale of individual bivalves, we studied whether this advantage occurs in optimizing food intake over native bivalves. We investigated feeding current characteristics, in which potential differences may ultimately lead to a differential food intake. We compared feeding currents of the invasive epibenthic non-siphonate Pacific oyster to those of two native bivalve suspension feeders: the epibenthic siphonate blue mussel Mytilus edulis and the endobenthic siphonate common cockle Cerastoderma edule. Inhalant flow fields were studied empirically using digital particle image velocimetry and particle tracking velocimetry. Exhalant jet speeds were modelled for a range of exhalant-aperture cross-sectional areas as determined in the laboratory and a range of filtration Communicated by S.A. Poulet. K. Troost W. J. Wolff Marine Benthic Ecology and Evolution, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands E. J. Stamhuis Ocean Ecosystems, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands K. Troost (&) Wageningen IMARES, Yerseke, P.O. Box 77, 4400 AB Yerseke, The Netherlands e-mail: [email protected] L. A. van Duren DELTARES, P.O. Box 177, 2600 MH Delft, The Netherlands
rates derived from literature. Significant differences were found in inhalant and exhalant current velocities and properties of the inhalant flow field (acceleration and distance of influence). At comparable body weight, inhalant current velocities were lower in C. gigas than in the other species. Modelled exhalant jets were higher in C. gigas, but oriented horizontally instead of vertically as in the other species. Despite these significant differences and apparent morphological differences between the three species, absolute differences in feeding current characteristics were small and are not expected to lead to significant differences in feeding efficiency.
Introduction Introduced oysters Since their initial introduction in the Oosterschelde estuary (SW Netherlands) in 1964 (Drinkwaard 1999a), Pacific oysters Crassostrea gigas (Thunberg) have been spreading rapidly, forming large and dense oyster reefs in the intertidal and subtidal (Drinkwaard 1999b; Wolff and Reise 2002; Dankers et al. 2006). While the Pacific oyster stock in the Oosterschelde estuary was expanding, stocks of the most common native b
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