Food Sources for Ruditapes philippinarum in a Coastal Lagoon Determined by Mass Balance and Stable Isotope Approaches

Abstract

The relationship between the food demand of a clam population (Ruditapes philippinarum (Adams & Reeve 1850)) and the isotopic contributions of potential food sources (phytoplankton, benthic diatoms, and organic matter derived from the sediment surface, seagrass, and seaweeds) to the clam diet were investigated. In particular, we investigated the manner in which dense patches of clams with high secondary productivity are sustained in a coastal lagoon ecosystem (Hichirippu Lagoon) in Hokkaido, Japan. Clam feeding behavior should affect material circulation in this lagoon owing to their high secondary productivity (ca. 130 g C m−2 yr−1). Phytoplankton were initially found to constitute 14–77% of the clam diet, although phytoplankton nitrogen content (1.79–4.48 kmol N) and the food demand of the clam (16.2 kmol N d–1) suggest that phytoplankton can constitute only up to 28% of clam dietary demands. However, use of isotopic signatures alone may be misleading. For example, the contribution of microphytobenthos (MPB) were estimated to be 0–68% on the basis of isotopic signatures but was subsequently shown to be 35±13% (mean ± S.D.) and 64±4% (mean ± S.D.) on the basis of phytoplankton biomass and clam food demand respectively, suggesting that MPB are the primary food source for clams. Thus, in the present study, the abundant MPB in the subtidal area appear to be a key food source for clams, suggesting that these MPB may sustain the high secondary production of the clam.

Spatial variability in an estuarine phytoplankton and suspended microphytobenthos community

“…Our findings suggest that both PPL and SMPB contributed to estuarine material circulation, and that their distributions differed spatially. SMPB are also considered an important food source for filter feeders inhabiting the shallow areas of estuaries (De Jonge & Van Beusekom 1992, Komorita et al 2014; therefore, our results provide data on possible spatial differences in food web structure in estuaries (Deegan & Garritt 1997, Kanaya et al 2007, which affect the processes of material circulation. In future studies, the biomass of PPL and SMPB in the Lake Furen water column should be quantified to further our understanding of their roles in estuarine material circulation.…”

“…Microphytobenthos (MPB) on sediments and/or plants (Yamaguchi 2011) are food sources for both deposit and filter feeders (De Jonge & Van Beusekom 1992, Komorita et al 2014. This is because of their significant production comparable to that of PPL (Cahoon & Cooke 1992, Gillespie et al 2000 and their suspension in the water column as SMPB.…”

Mercury in the food chain of the Lagoon of Venice, Italy

“…Solid line shows regression of d 13 C versus d 15 N values for all primary consumers (see text) used to determine baseline d 15 N and the trophic position of all consumers (for details see Table 1 line with the literature (e.g. Machás and Santos, 1999 and references therein;Vizzini and Mazzola, 2008;Carlier et al, 2009;Komorita et al, 2014).…”

Use of sediment dwelling bivalves to biomonitor plastic particle pollution in intertidal regions; A review and study

“…Both the varnish (Nuttallia obscurata) and Manila (Venerupis philippinarum) clam are infaunal sediment dwelling bivalves, that both filter and deposit feed exploiting food sources within sediments as well as at the sediment water interface [21,22]. Varnish clams can be found up to 30 cm in depth [21] and the Manila will burrow to a sediment depth that is dependent on its size (small versus large) and sediment characteristics i.e., ease of burrowing and energy required to burrow [23].…”