1. The importance of long-chain polyunsaturated fatty acids (PUFAs), in particular eicosapentaenoic acid (EPA), for the growth and development of Daphnia galeata (Sars) was tested using food types differing in PUFA and EPA contents. 2. Life history experiments of D. galeata fed with the cryptophyceans Rhodomonas lacustris (Pascher & Ruttner) and Cryptomonas pyrenoidifera (Gentler), and the green alga Scenedesmus acutus (Meyen), showed that both cryptophycean species were higher in quality than S. acutus. 3. Since the cryptomonads contained significant amounts of EPA while no EPA could be detected in Scenedesmus, tests were performed to ascertain whether EPA was responsible for the differences in food quality. Feeding daphnids a mixed diet of Scenedesmus and emulsion particles that were rich in EPA and DHA, resulted in a significant improvement in the intrinsic population growth rate. The initial difference in food quality between Scenedesmus and the cryptomonads was completely compensated for by addition of emulsion to the Scenedesmus food. 4. From the observed stimulatory effect of the addition PUFA to the daphnid diet, this study concludes that the presence of such long-chain PUFA improves food quality for daphnids. [KEYWORDS: Blue-green-algae; lipid-composition; microalgae; phytoplankton; quality; magna; fish]
Original languageEnglish
JournalFreshwater Biology
Journal publication date1997

ID: 94447