CPR deployed

By: Christie Evans

In the wee hours of the morning in the waters off Pt. Hacking the CPR (continuous plankton recorder) was deployed off the stern of the ship. Not having seen one before my expectation was for a large net like structure so this small stainless steel rocket at 1m was initially somewhat underwhelming. Having spoken to Ruth Eriksen (CSIRO) however, it is a very clever and unique device. Originally developed in the 1930s by Alister Hardy it has changed very little. When dragged through the water, plankton enter the front and are caught in layers of silk 270 microns thick which then wind onto a roll inside the chamber. Formaldehyde is passed over the samples to preserve them for scientific examination.

There was an air of excitement as well as trepidation as the IMOS (Integrated Marine Observing System) CPR was retrieved from the sea. Ruth and I opened the device and extracted the cassette. Ruth gave a sigh of relief as the recorder had worked perfectly trapping the plankton between the layers of silk. Looking at the top layer of silk we could see krill (orange) and algae (green).