THE MACRO-FLOW PLANKTOMETER - EVALUATION OF A PROCEDURE FOR THE AUTOMATED MEASUREMENT OF PARTICULATE MATTER IN PELAGIC SYSTEMS

This article describes a test of the macro-flow planktometer in respec t to its applicability to the biological science. The recording instru ment is a flow measurement device, that uses the Coulter-principle and an integrated image capturing system for the automated detection and measurement of particulate matter in the diameter scale from 100 to 30 00 mu m. The evaluation used four different sample materials (Artemia- eggs, Artemia-nauplii, fish eggs and plankton) and was subdivided in a quantitative (measurement procedure) and a qualitative (image analysi s) part. Repetitive measurements with the MFP (800 - 2000 particles) s howed a very high precision in the determination of the overall partic le volume as well as in the measured particle counts. Partly the compa rison of the particle volume detection by means of a binocular with th e MFP-measurements showed insufficient results. Following the addition of different fixatives the MFP measurements showed a decline in sampl e volume (as a result of a growing particle conductivity), which in mo st cases followed an exponential pattern. This fact complicates the me asurement of fixed samples as a correction factor would have to be det ermined for every single combination of the biochemical structure of t he particle, the fixation method used and the time span between fixati on and measurement. Human image analysis made it possible to discrimin ate individual particle classes and to attach them to specific volume ranges in the MFP measurement. It was also possible to record a repres entative random sample with the MFP image analysing system. Restrictio ns only arose when the particle counts in a specific particle class we re too low or the volume range of different particle classes showed la rge overlaps.