Caron methodology for nanoplankton counts

David Caron and Darcy Lonsdale
WHOI

Methodology for nanoplankton counts

Samples of phototrophic (pnp) and heterotrophic (hnp) nanoplankton (2-20 micrometers) were preserved in a final concentration of 1% formalin and stored at 4C. Slides were prepared for enumeration by epifluoresence microscopy within 24 hrs of preservation by staining with DAPI at a final concentration of 25 microgram/ml (Caron, 1983; Sherr et al, 1993). Phototrophic (chloroplast-bearing) nanoplankton were distinguished from heterotrophs by the autofluoresence of chlorophyll a. Although individual Phaeocystis antarctica cells are in the nanoplankton size range (2-20 micrometer), colonies generally fall in the range of microplankton (20-200 micrometer) or larger. Thus flagellated, single cells of P. antarctica were enumerated as phototrophic nanoplankton, and non-motile cells associated with colonies were included in the counts of microplankton. Carbon biomass was estimated using the modified Strathmann equation (Smayda, 1978) for biovolumes that were determined by calculating the volume of an appropriate geometric shape (usually a sphere).

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.

Smayda, T.J. (1978) From phytoplankton to biomass. In: Sournia, A. (Ed.) Phytoplankton manual. United Nations Educational Scientific and Cultural Organization, Paris, pp. 273-279.