SS4.07 Lipids/Fatty Acids in Ecological Research
Date: Tuesday, June 11, 2002
Time: 4:45:00 PM
Location: Saanich
 
Von ElertE, University of Constance, Konstanz, Germany, eric.vonelert@uni-konstanz.de
 
LIMITATION BY POLYUNSATURATED FATTY ACIDS IN DAPHNIA: AN EXPERIMENTAL TEST
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Correlative evidence from field data suggests that the availability of single polyunsaturated fatty acids (PUFAs) might constrain trophic transfer efficiency at the primary producer - grazer interface when sufficient phosphorus is available. In order to test if somatic growth of Daphnia is sensitive to the availability of single PUFAs I devised a new method to load algal cells with single fatty acids. The effect of this supplementation on the food quality was subsequently investigated in growth assays with a clone of D. galeata. While supplementation of Scenedesmus obliquus with monoenoic fatty acids and n-6 PUFAs had no effect, addition of 18:3n-3 and 20:5n-3 and 22:6n-3 improved growth of Daphnia indicating that the quality of S. obliquus is constrained by the low content of n-3 PUFAs. Investigation of the underlying conversions of these n-3 PUFAs in Daphnia suggest that growth on S. obliquus is limited by the availability of 20:5n-3.