SEASONAL PATTERNS OF TOTAL AND ENERGY RESERVE LIPIDS OF DOMINANT ZOOPLANKTONIC CRUSTACEANS FROM A HYPER-EUTROPHIC LAKE

Seasonal patterns of lipid reserves and lipid classes of dominant zooplankton in a hyper-eutrophic lake were examined in relation to algal food resources. Triacylglycerol was the principle lipid energy reserve in all five species examined. During the height of the yearly Aphanizomenon flos-aquae bloom, lipid levels of the principle herbivores (Daphnia pulex and Leptodiaptomus sicilis) and an omnivore (Diacyclops bicuspidatus thomasi), were at their lowest concentration, suggesting that this cyanobacterium is nutritionally inadequate. As the cyanobacterial bloom began to collapse, bacterial numbers increased rapidly. The increase in bacterial numbers coincided with a large increase in areal lipid energy reserves of Diaphanosoma leuchtenbergianum and Chydorus sphaericus. Examination of seasonal patterns in the biomass of different algal species suggested that Rhodomonas minuta and Cryptomonas erosa played a key role in nutrition, lipid deposition, and reproduction of D. pulex and L. sicilis.