Turbulence increases the average settling velocity of phytoplankton cells.

Microscale Complexity in the Ocean: Turbulence, Intermittency and Plankton Life

This contribution reviews the nonlinear stochastic properties of turbulent velocity and passive scalar intermittent fluctuations in Eulerian and Lagrangian turbulence. These properties are illustrated with original data sets of (i) velocity fluctuations collected in the field and in the laboratory, and (ii) temperature, salinity and in vivo fluorescence (a proxy of phytoplankton biomass, i.e. u...

Influence of water-column depth and mixing on phytoplankton biomass, community composition, and nutrients

We independently manipulated mixing intensity (strong artificial mixing vs. background turbulence) and water-column depth (2 m, 4 m, 8 m, and 12 m) in order to explore their separate and combined effects in a field enclosure experiment. To accentuate the vertical light gradient, enclosures had black walls, resulting in a euphotic depth of only 3.7 m. All enclosures were placed in a well-mixed w...

The effect of feed ingredients on the settling velocity of feces in Tilapia (Oreochromis niloticus L.)

A New Approach for Obtaining Settling Velocity in a Thickener Using Statistical Regression: A Case Study

In this research work, the parameters affecting the settling velocity within the thickeners were studied by introducing an equivalent shape factor. Several thickener feed samples of different densities including copper, lead and zinc, and coal were prepared. The settling tests were performed on the samples, and the corresponding settling curves were plotted. Using the linear regression analysis...

Population dynamics of sinking phytoplankton in stratified waters

We analyze the predictions of a reaction advection di usion model to pinpoint the nec essary conditions for bloom development of sinking phytoplankton species in strati ed waters This reveals that there are two parameter windows that can sustain sinking phytoplankton a turbulence window and a thermocline depth window The two win dows are delimited by four critical parameters a minimal and maxim...