Daphnia magna filtration efficiency and mobility in laminar to turbulent flows

摘要

AbstractDaphniaare filter feeder organisms that prey on small particles suspended in the water column. SinceDaphniaindividuals can feed on wastewater particles, they have been recently proposed as potential organisms for tertiary wastewater treatment. However, analysing the effects of hydrodynamics onDaphniaindividuals has scarcely been studied. This study focuses then, on quantifying the filtration and swimming velocities ofD.magnaindividuals under different hydrodynamic conditions. BothD.magnafiltration and movement responded differently if the flow was laminar or if it was turbulent. In a laminar-dominated flow regimeDaphniafiltration was enhanced up to 2.6 times that of a steady flow, but in the turbulent-dominated flow regimeD.magnafiltration was inhibited. In the laminar flow regimeD.magnaindividuals moved freely in all directions, whereas in the turbulent flow regime they were driven by the streamlines of the flow. A model based onDaphnia-particle encountering revealed that the filtration efficiency in the laminar regime was driven by the length of theD.magnaindividuals and the shear rate imposed by the system.Graphical abstractDisplay OmittedHighlights•In the Couette laminar flow theD.magnafiltration increases linearly with shear.•Turbulent flow completely inhibitsD.magnafiltration.•Turbulent regime restrictsD.magnaswimming capacity.•D.magnafiltration is predicted to increase with the third power of the body length.