Distinguishing Zooplankton and Microstructure as Sources of Acoustic Scattering Within an Internal Wave. Although the primary use of this instrument is the mapping of zooplankton and micronekton populations, the presence of internal waves in the water column potentially creates an ambiguity in interpreting the acoustic data. Acoustic scattering can be caused by both zooplankton and turbulent microstructure in the water column. A close analysis of an internal wave soliton shows that dominant scattering in a particular region may be due to plankton at one depth and turbulence at another. This implies that in some regions of the water column impacted by the soliton scattering from turbulence can dominate the total backscattering, thereby obscuring the scattering from plankton.
Many scientists use acoustics to estimate the abundance of biological animals in the water column.
Many animals in the ocean reflect sound energy that hits them, thus if you send out a sound wave, you can listen for the echo and from this information you may try to estimate how many animals are in the water column. In this way, acoustic surveys of zooplankton can cover much larger territory than a conventional net survey would. Since ship time is expensive, acoustic backscatter from animals is a useful measurement to make. However there are limitations to acoustics. One is that you don't know which animals are actually in the water column reflecting the sound back to you.