Effect of the addition of polyunsaturated fatty acids to the diet on the growth and fecundity ofDaphnia galeata

Abstract

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.

Interaction of changes in food quality and temperature reveals maternal effects on fitness parameters of a keystone aquatic herbivore

“…It is thus commonly accepted that Daphnia growth on green algae is limited primarily by EPA availability (von Elert 2002;Becker andBoersma 2003, 2005). Weers and Gulati (1997) report that the quality of Scenedesmus food for Daphnia was ameliorated by addition of EPA to the level observed for Cryptomonas or Rhodomonas. Therefore, in the absence of elemental nutrient limitation, the EPA content of a phytoplankton diet can be considered a proxy for food quality.…”

“…PUFAs, such as EPA, are important for maintaining membrane fluidity of ectotherms at low temperatures, and some aquatic ectotherms are capable of increasing the PUFA content of their lipid membranes in response to cold (Farkas et al 1984). However, Daphnia have shown low rates of conversion of C18-PUFA into EPA (Farkas et al 1984;Weers et al 1997), and their fatty acid composition largely resembles that of their diet (Weers et al 1997). Therefore Masclaux et al (2009) suggested that a higher dietary supply of EPA might be required at low temperatures.…”

Nutritional quality of seston for the freshwater herbivore Daphnia galeata × hyalina: biochemical versus mineral limitations

“…Every day, fresh emulsions of ICES 30/0.6/C, supplied by INVE technologies Belgium (Coutteau et al 1996;Boersma 2000), were prepared by adding 0.5 mg wet weight of emulsion (0.4 mg C) per litre of lake seston. Analysis of the particle size showed that the emulsion particles were in the range of 1-2 µm, but that they were readily taken up by daphnids (see also Weers and Gulati 1997a). For details of the fatty acid content of the emulsions see Boersma (2000).…”

C and P in aquatic food chain: A review on C:P stoichiometry and PUFA regulation

“…Such variations of food quality correspond to the predictions of experiments on algal taxa with PUFA . When PUFA emulsions were added to cultures of Scenedesmus acutus, a green algae, the Daphnia growth rate was observed similar to those observed for high quality cryptophytes (Weers and Gulati, 1997). Demott and Müller-Navarra (1997) found that adding PUFA emulsions to PUFA-poor cyanophytes Synechococcus improved the food quality of this mixture to the level observed for Scenedesmus acutus.…”

“…However, differences in such conversion capacities and consumers types in trophic level have further implication on C transfer dynamics (Goedkoop et al, 2007). Where Bosmina leideri is less dependent on high food quality (Schulz and Sterner, 1999), Daphnia shows high dependency on EPA (Weers and Gulati, 1997;Boersma, 2000). The calanoid copepod Acartia tonsa shows very low fecundity on a diet deprived of EPA and DHA (Ederington et al, 1995;Kleppel et al, 1998) whereas the harpacticoid copepod Thisbe holothyria, a detritus feeder, can complete ontogenesis on C20 PUFA deficient diet due to de novo synthesis of EPA and DHA from ALA (Norsker and Støttrup, 1994).…”