What Is the Potential of (Water Flea) Predation as a Means of Biological Suppression of (Golden Algae) Blooms in Ecologically Relevant Conditions?

This study explores the interaction between and under low-salinity conditions. showed reduced growth below 0.4 PSU and peaked at 1.0 PSU within the tested 0.2-1.0 PSU range. , exposed to across 0.0-6.0 PSU, experienced increased mortality at 4.0 and 6.0 PSU, but tolerated 0.0-1.0 PSU well and grazed actively on without significant vitality loss. This range reflects conditions observed in the Oder River during the 2022 fish die-off. The count of cells did not vary significantly across the 0.2 to 1.0 PSU range of salinities in presence, except at 0.6 PSU. All daphnids survived even at densities of 1 × 10 cells/mL, though increasing algal concentrations reduced juvenile growth rates. Direct observation under a microscope confirmed algal ingestion. Toxin accumulation in cells and medium likely reduced grazing efficiency via allelopathic effects. The study assessed whether can tolerate prymnesins while maintaining feeding under varying salinities. Results suggest that could act as a biological suppressor of golden algae under certain environmental conditions, though further work is needed to quantify grazing efficiency and prymnesins concentrations.