 Phytoplankton are often measured by optical instruments that can detect fluorescence such as LIDAR, and zooplankton are often measured by acoustic instruments that can detect acoustic backscattering such as ABS.These extraordinary concentrations of plankton have important implications for many aspects of marine ecology (e.g., phytoplankton growth dynamics, zooplankton grazing, behaviour, environmental effects, harmful algal blooms), as well as for ocean optics and acoustics.It is important to note that zooplankton thin layers are often found slightly under phytoplankton layers because many feed on them.