From algal competition to animal production: Enhanced ecological efficiency of Brachionus plicatilis with a mixed diet

Abstract

The food-chain transmission of mineral nutrient effects to zooplankton production via phytoplankton competition was studied by two-stage experiments with a mixed phytoplankton assemblage from the Indian Ocean and the rotifer species Brachionus plicatilis. Phytoplankton species composition was steered by nutrient competition in the first stage of the cultures. High atomic Si: N ratios (>1:1) in the medium resulted in diatom dominance, and low ones resulted in flagellate dominance. Medium Si:N ratios (0.3-0.6:1) resulted in even mixtures of both types of algae. The phytoplankton assemblage resulting from competition was used as food for Brachionus. An even mixture between diatoms and flagellates in the food resulted in higher Brachionus production than one-sided food mixtures.