AB 6:235-246 (2009)  -  DOI: https://doi.org/10.3354/ab00131

In situ evidence for pre-capture qualitative  selection in the tropical bivalve Lithophaga simplex

Gitai Yahel1,4,*, Dominique Marie2, Peter G. Beninger3, Shiri Eckstein1, Amatzia Genin1

1The Interuniversity Institute for Marine Sciences of Eilat and the Department of Evolution, Systematics and Ecology, The Hebrew University of Jerusalem, PO Box 469, Eilat 88103, Israel
2Station Biologique de Roscoff, UMR7144, CNRS et Université Pierre et Marie Curie, Place G. Teissier, 29682 Roscoff, France
3ISOMer—Laboratoire de Biologie Marine, Faculté des Sciences—Université de Nantes, 2 Chemin de la Houssinière, 44322 Nantes Cedex 03, France
4Present address: The School of Marine Sciences and Marine Environment, Ruppin Academic Center, Michmoret 40297, Israel

ABSTRACT: Few feeding studies have been performed on tropical bivalves, and in situ feeding studies are lacking altogether. We investigated retention efficiencies for natural particles in the coral-boring tropical mytilid Lithophaga simplex. Using the in situ InEx technique (Yahel et al. 2005; Limnol Oceanogr Methods 3:46–58) SCUBA divers collected samples from the water inhaled and exhaled by undisturbed bivalves at the coral reef of Eilat (Gulf of Aqaba). Particle retention efficiencies were determined using flow cytometry analysis of the paired water samples. The photosynthetic bacterium Synechococcus (0.9 ± 0.1 µm) and larger eukaryotic algae (1 to 10 µm) were preferentially retained by the bivalve with removal efficiencies of up to 90% (1996 to 2000: averages of 69 ± 14% and 60 ± 17%, respectively, n = 74 individual bivalves). The minute photosynthetic bacterium Prochlorococcus (0.4 ± 0.1 µm) was also moderately retained (41 ± 19%). Only a small proportion of the non-photosynthetic bacteria (0.3 ± 0.1 µm) were retained (5 ± 18%, median of 9%), despite their numerical dominance in the plankton and considerable size overlap with Prochlorococcus. Size-independent preferential retention was also observed within particle types: (1) L. simplex more efficiently retained Prochlorococcus and picoeukaryotic algal cells with higher chlorophyll content and (2) the small fraction of non-photosynthetic bacteria retained did not differ in size, but had higher nucleic acid content (compared to the inhaled population) an indicator for viable and active bacteria. We conclude that particle retention is not strictly size-dependent in L. simplex, and probably involves other cell attributes such as cell surface properties and/or motility.

KEY WORDS: Suspension feeding · Nutrition · Selectivity · Coral reefs

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Cite this article as: Yahel G, Marie D, Beninger PG, Eckstein S, Genin A (2009) In situ evidence for pre-capture qualitative  selection in the tropical bivalve Lithophaga simplex. Aquat Biol 6:235-246. https://doi.org/10.3354/ab00131

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