Field Collections Zooplankton are normally captured in plankton nets. These nets were in use over 100 years ago, as they are still today. There have been many adaptations and modifications over the years. Most notably have been different mechanisms allowing the nets to be deployed closed, opened at depth, fished, and then closed before retrieval. The type of organisms collected depends inpart upon the mesh size, normally measured in microns.
Smaller mesh tend to clog the nets.
In recent years there has been a move towards using photometric measurements and even sound to make direct measurements. Laboratory Analysis Plankton are generally examined for some estimate of total biomass . This includes their displacement volume, wet weight, or dry weight. This is very time consuming. These data may then be analyzed using any of the normal statistical analyses.