Continuous Plankton Recorder (CPR)

What it's used for

The CPR is a self-contained sampling instrument that is towed behind the ship at about 10 m depth. It is towed at a normal ship's speed and can operate in nearly all sea conditions.

It is used to collect data along long transects to provide spatial and temporal coverage of plankton communities.

Despite the fact that CPR technology has remained virtually unchanged since 1927, it remains one of the best ways of simultaneously monitoring the phytoplankton and zooplankton in our oceans over large distances.

How it works

As the CPR is towed, water and plankton enter the instrument through an opening about the size of a thumbnail. The plankton then gets filtered onto a fine band of silk. The silk and plankton are preserved by spooling into a special chamber within the instrument which rotates at a pre-determined speed.

Back in the laboratory, the silk is divided into samples representative of different locations, allowing scientists to determine the location at which they are caught - and map their distributions and abundance. The samples can be analysed according to the Phytoplankton Colour Index (PCI) as well as microscopic analysis, where individual phytoplankton and zooplankton are identified and counted.