Feeding performance of the copepod Clausocalanus lividus (Frost and Fleminger, 1968)

Clausocalanus is a small-sized copepod genus that is widespread in the world ocean, but it has been poorly investigated from a biological and ecophysiological point of view. In this study, we targeted the species Clausocalanus lividus, one of the less studied circumglobally occurring congeners of the genus, to explore a number of aspects of its feeding. We examined the functional feeding response of adult wild females to seven monospecific diets with prey items differing in terms of size (ESD: 4-28 μm) and motility. Clausocalanus lividus did not significantly clear the small flagellate, Isochrysis sp., while for the larger-sized food items offered (ESD > 5 μm), it exhibited a type II functional feeding response. Its maximum daily carbon intake ranged from 54 to 137% of its body carbon and was generally higher on prey with ESD > 15 μm, being up to 17 μg C cop^-1 day^-1 for the diatom Thalassiosira weissflogii. The clearance maxima (10-308 mL cop^-1 day^-1) were generally associated with prey size (increasing with the ESD). The estimated feeding rates of C. lividus are discussed in relation to the concentration and size of food and compared to findings for other congeners.