David Caron
WHOI

Methods for nanoplankton counts

Assemblages of phototrophic (pnp) and heterotrophic (hnp) nanoplankton
were preserved in a final concentration of 1% formalin and stored at 4
degrees C. Samples were prepared for enumeration by epifluoresence
microscopy within 24 hrs of preservation by staining with DAPI at a
final concentration of 25 ug/ml (Caron, 1983; Sherr et al, 1993).
Phototrophic (chloroplast-bearing) nanoplankton were distinguished from
heterotrophs by the autofluoresence of chlorophyll a. Biovolumes were
estimated by calculating the volume of an appropriate geometric shape
(usually a sphere) from samples at 4 representative depths and then
extrapolated through the water column.

References

Caron, D.A. (1983) Technique for enumeration of heterotrophic and
phototrophic nanoplakton, using epifluoresence microscopy, and
comparison with other procedures. Applied and Enviromental
Microbiology, 46, 491-498.

Sherr, E.B., D.A. Caron and B.F. Sherr (1993) Staining of heterotrophic
protists for visualization via epifluoresence microscopy. In: Handbook
of methods in aquatic microbial ecology, Kemp, P., J. Cole, B. Sherr
and E. Sherr, eds. Lewis Publishers, Boca Raton, pp. 213-227.