Arctica islandica (Bivalvia) selective feeding on natural plankton in the White Sea

TL;DR: <italic>Arctica islandica</italic> selectively feeds on natural plankton in the White Sea, with diatoms and heterotrophic dinoflagellates forming the bulk of its ration.

Abstract: <title>Abstract</title> The ocean quahog <italic>Arctica islandica</italic> (L.) has been the focus of extensive research due to its commercial value and extreme longevity. However, little is known about its natural trophic behavior. In a feeding experiment that used plankton and clams collected from the White Sea coast, <italic>Arctica</italic> cleared a wide spectrum of particles, ranging from picoplanktonic cyanobacteria and nano-cryptophytes to diatom chains. Diatoms and heterotrophic dinoflagellates formed the bulk of <italic>Arctica</italic> ration, which equaled ~ 1% of its tissue carbon per day. The estimated prey selectivity increased with particle size, but the clams also discriminated between prey of similar size and taxonomy. The measured <italic>Arctica</italic> mass-specific filtration rates corresponded to those published earlier for intertidal mussels. Implications for <italic>Arctica</italic> growth are discussed.