Population Growth of the Freshwater Cladoceran, Diaphanosoma excisum, Fed Different Densities of the Alga, Scenedesmus acuminatus

Abstract

The freshwater cladoceran, Diaphanosoma excisum Sars 1885, was fed the micro-alga Scenedesmus acuminatus, at one of six densities (0.5, 1.0, 1.5, 2.0, 3.0, or 4.0 x 106 cells/ml) in 40-l glass aquaria. The D. excisum density increased as the Scenedesmus density increased to 1.5 x 106 cells/ml, in which it peaked at 7345 individuals per liter. Population growth was inhibit- ed at higher algae densities. The percent of egg-bearing females and the number of eggs per egg-bearing female followed a similar pattern. Production of approximately 7000 individuals per liter was encouraging from a mass production point of view and indicates that S. acuminatus is suitable for use as a live starter feed for D. excisum which, in turn, is a live feed for larvae of induced-breeding in fish hatcheries.