Food ingestion and growth of the diatom-feeding nematode Chromadorita tenuis

Abstract

Feeding rates and growth of the free-living brackish water nematode Chromadorita tenuis (G. Schneider, 1906) was studied throughout its life cycle. Populations were fed with the pennate diatom Nitzschia palea var debilis (Kütz.) Grunow in the laboratory at 18°C in agar plates based on seawater of 6‰ S. On the average, during the first day after hatching they ingest 1 μg of cell contents, equal to 20 times the body weight, and the body weight increased from 3.6 to 6.9 ng C. During the entire 12.5 d of juvenile life the weight increased 40 times, whereas the weight only doubled during adult life, which is almost entirely devoted to reproduction. Adult virgins are larger than mated females. The large size of adult virgins indicates that about 50% of the gonad energy might be transferred to somatic growth. The size-frequency distribution of adult body lengths of a laboratory grown population as compared to four wild populations shows that the food offered to the laboratory population was of a poor quality.