Dataset: Orientation and growth of colonies of four diatom species (Stephanopyxis turris, Pseudo-nitzschia sp., Skeletonema sp., and Odontella sinensis) in Couette flow

Uni-algal cultures of the colonial diatoms Stephanopyxis turris, Pseudo-nitzschia sp., Skeletonema sp., and Odontella sinensis were grown in 2 separate Couette chambers under controlled shear conditions for up to 24 days. The Couette chambers (40 cm height) consisted of an inner rotating cylinder (12.7 cm radius) and an outer stationary cylinder (14.92 cm radius). A laminar flow chamber rotated at 0.5 rpm and a turbulent flow chamber rotated at 13 rpm. The gap between the cylinders was filled with 8 L of sterile L1 medium (Guillard and Hargraves 1993). Experiments took place in a temperature and light controlled walk-in incubator at 20° C with a 12:12 hour light:dark cycle. Light was provided by cool white fluorescent lamps producing 33 µmol photons m⁻² s⁻¹ at the center of each chamber.

Digital holograms through the entire height of each Couette chamber (40 cm) were acquired at ~1 day intervals during each experiment. Each hologram imaged 19.25 mL of water. The total volume imaged and analyzed on each day and for each chamber was ~1.5 L.

A custom digital holographic microscope (DHM) was constructed to image particles within the Couette chambers. Coherent illumination was provided by a green (532 nm) nanosecond pulsed laser. The incident beam was directed upward through the bottom of the chamber and images were acquired by a CCD camera (4896 x 3264 pixels) positioned above the chamber looking downward through the illuminated volume. An objective lens in front of the camera increased magnification and positioned the hologram image plane at the water surface. Hologram resolution was 1.74 µm/pixel.