Absolute abundances (concentrations) of dinoflagellate cysts are often determined through the addition of Lycopodium clavatum
marker-grains as a spike to a sample before palynological processing.
An inter-laboratory calibration exercise was set up in order to test the
comparability of results obtained in different laboratories, each using
its own preparation method. Each of the 23 laboratories received the
same amount of homogenized splits of four Quaternary sediment samples.
The samples originate from different localities and consisted of a
variety of lithologies. Dinoflagellate cysts were extracted and counted,
and relative and absolute abundances were calculated. The relative
abundances proved to be fairly reproducible, notwithstanding a need for
taxonomic calibration. By contrast, excessive loss of Lycopodium
spores during sample preparation resulted in non-reproducibility of
absolute abundances. Use of oxidation, KOH, warm acids, acetolysis, mesh
sizes larger than 15 µm and long ultrasonication (> 1 min) must be
avoided to determine reproducible absolute abundances. The results of
this work therefore indicate that the dinoflagellate cyst worker should
make a choice between using the proposed standard method which
circumvents critical steps, adding Lycopodium tablets at the end of the preparation and using an alternative method.
- Programområde 5: Natur og klima