|Stable isotopes as a tool for nutrient assimilation studies in larval fish feeding on live food|In: Aquatic Ecology. Springer: Dordrecht; London; Boston. ISSN 1386-2588, more
Carbon isotope ratio; Feeding experiments; Fish larvae; Food absorption; Livestock food; Nutrient cycles; Nutritional requirements; Cyprinus carpio Linnaeus, 1758 [WoRMS]; Panagrellus redivivus; Fresh water
|Authors|| || Top |
- Schlechtriem, C.
- Focken, U.
- Becker, K.
Many fish and crustacean larvae require live food at the onset of exogenous feeding. It is generally difficult to include chemical or isotopic markers in live food for nutrient studies. The soil nematode Panagrellus redivivus, a potential live food for fish and crustacean larvae, can be mass cultured on a wide range of media, which offers the opportunity to produce isotopically distinct live food. In this study P. redivivus was cultured separately on wheat- and corn-based media. As a result nematodes with different stable carbon isotope signatures (13C) could be obtained. Both types of nematodes were tested on first-feeding Cyprinus carpio larvae in a feeding experiment lasting six days. In contrast to the nematodes cultured on the wheat-based medium, the 13C values of nematodes produced on the corn-based medium were clearly different to the isotopic signature of the fish larvae. 13C values for lipids and lipid-free matter of fish larvae sampled on Day 2, 4 and 6 after first feeding were clearly influenced by the stable isotopic pattern of the nematodes. The assimilation of lipid and lipid-free matter was calculated by a two source mixing model. The onset of nutrient retention as well as the proceeding assimilation of feed carbon into the body tissues could be calculated precisely for nematodes cultured on the cornbased medium. The possibility to mass produce live food organisms with a controllable isotopic signature provides new possibilities for nutritional studies on fish and crustacean larvae.