Ingestion and clearance rates, feeding behaviors and life history variables of the marine cladoceran Penilia avirostris were evaluated over a range of food concentrations encountered in nature (0.01–3.0 mm 3 1 −1 of Isochrysis galbana ). Ingestion rates increased and clearance rates decreased with increasing food concentration. No maximum feeding thresholds were observed over the range of algal concentrations offered. Weight-specific ingestion rates decreased with increasing body weight. Feeding behaviors such as mandibular activity, abdominal claw rejections of clogged feeding structures and feeding appendage activity decreased at a food level of 0.3 mm 3 l −1 of l. galbana . Penilia avirostris had very poor survivorship at extremely low (0.01 mm 3 l −1 and high (3.00 mm 3 l −1 ) food levels. Mortality was hardly affected at food levels of 0.03–1.0 mm 3 l −1 Reproduction did not occur at food levels of ≥0.3 mm 3 l −1 or at the lowest level offered (0.01 mm 3 l −1 . Generation times were about 6 days at a food level of 0.1 mm 3 l −1 Gross growth efficiencies (including growth of young in the mother's brood pouch) were high, hardly changed during the first 3 days of life, but began to decrease when young started to develop in the brood pouch. Although P. avirostris is generally most abundant in near- and in-shore waters, characterized by high particulate concentrations, the organism appears to be able to grow and reproduce at particulate concentrations (0.03 mm 3 l −1 = 6 μg C l −1 ) which are low for neritic and most pelagic environments. Penilia avirosrris seems to be well adapted for life at low resource levels.
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Paffenhöfer et al. (1986) studied this question.