Download (3148Kb) - OceanRep

With the present thesis a method for the analysis of zooplankton field
samples by means of quantitative automated image analysis is
introduced. The procedure served for the investigation of net samples
collected during the "Meteor - Equator - Expedition 1979".
The image analysis method has been developed for the "Quantimet 720"
system produced by "Cambridge Instruments". A detailed description of
the system's structure and its mode of operation is given. For the
investigation of the zooplankton samples the system was equipped with
a "Tessovar" microscope by Zeiss that enabled measurements by a 2-fold
and a 3.2-fold magnification. Using this system a quick, precise and
objective measurement of planktonic organisms is possible. Only copepods
and their developmental stages were investigated. The geometrical
parameters, length and area, were used for the measurements. Assuming
that the ideal shape of a copepod equals an ellipsoid, the individual
volume was calculated. The processing of the automatically stored raw
data was carried out with specially developed computer programs. With
these programs a statistical analysis and the presentation of results
in the form of size - frequency - distributions are possible.
The potential measurement speed of the image analysis system was
reduced to eliminate errors caused by artefacts arising from the
adhering or overlapping of single organisms. Furthermore a counting
chamber was designed to allow the repositioning of the organisms
during measurement. The operator also has the possibility to append
additional information in the form of indices to the measured data.
The copepods have been differentiated into 4 fuctional groups:
floaters, swimmers, wrigglers and nauplii. A clear visual distinction
between these groups is easily made via the monitor and so a quick
index assignment is possible.
The described system works more slowly than the coulter - counter -
method but exceeds the traditional microscopic analysis in speed. Its
information content surpasses that of the coulter - counter - method
and is comparable with information gained by traditional microscopic