Kilham, S.S., D. A. Kreeger, C.E. Goulden, S. Lynn
Abstract:
The green alga Ankistrodesmus falcatus was grown under P-limitation or N-limitation at 25% of u-max, or exponentially in COMBO medium. It was characterized for the major biochemical constituents: proteins, carbohydrates, lipids and lipid classes. These algae were fed to Daphnia pulicaria at four food rations to measure fecundity and population growth responses. Fecundity measurements showed that food quality had a much bigger impact than food quantity for N-limited food, with fecundities depressed at all food levels compared to exponentially growing cells. Fecundity for animals grown on P-limited food showed both food quality and food quantity effects. Fecundities were significantly lower for P-limited cells, but there was some compensation at higher food quantities. Population growth rates were measured at two food levels of algae. The r-max was significantly lower at each food ration for both the LOW-P and the LOW-N algae compared to the non-limited algae. There was some compensation for food quantity in the LOW-P high ration case.
(Dept. Bioscience & Biotechnology, Drexel University, Philadelphia PA 19104, USA)
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