Microzooplankton sampling and sample processing. Samples of seawater from a desired depth are obtained using a Niskin bottle. The bottle (1), open at both ends, is lowered to the desired depth and then the top and bottom lids are closed. The water sample is preserved onboard typically with the Iodine-based Lugol's solution (2). Back in the laboratory, a subsample (usually 100 or 50 ml) of the preserved seawater is left to sediment over a glass-bottom settling chamber (3) for 24-48 hours. The cylinder holding most of the water (all but 3 ml) is slid off the settling chamber (4). The settling chamber is then examined using an inverted microscope (5). Visible in the camera screen image in the upper right is a small tontonnid oligotrich ciliate, and in the lower right a 10 µm white bar.
