David Garrison and Marcia Gowing

Microzooplankton Methods

Samples for microzooplankton biomass were obtained by taking ~ 2-liter
aliquots from standard hydrographic casts. Heterotrophic flagellates
and some nano-planktonic non-loricate ciliates were examined by
epifluorescence microscopy on samples preserved with approximately 0.5%
glutaraldehyde, concentrated on 0.8 micron, black Nuclepore filters,
and stained with the fluorochromes DAPI (Coleman 1980) and proflavin
(Haas 1982) following the protocol outlined by Verity and Sieracki
(1993).  Whole water samples were preserved with buffered
paraformaldehyde.  Larger heterotrophic dinoflagellates, and most of
the ciliates were enumerated from 50 or 100 ml of these preserved
samples that were settled and counted with an inverted microscope.
Biomass was estimated by converting cell volumes (calculated from
measurements of cell dimensions) using the relationship ((Log10 C =
0.94 (log10 V)-0.60); with C representing carbon as picograms per cell
and V representing total cell volume in cubic microns) for flagellates
(Eppley et al. 1970), and the relationship carbon per cell = 0.16
pgC/cubic micron (Stoecker et al. 1994).

Coleman, A.W.  1980.  Enhanced staining of bacteria in natural
environments by fluorochrome staining of DNA.  Limnol. Oceanogr.
25:948-951.

Eppley, R.W., F.M.H. Reid, J.D.H. Strickland.  1970.  The ecology of
the plankton off La Jolla, California, in the period April through
September, 1967.  (ed. J.D.H. Strickland), pt. III, Estimates of
phytoplankton crop size, growth rate and primary production.  Bull.
Scripps Inst. Oceanogr.  17:33-42.

Haas, L.W.  1982.  Improved epifluorescence microscopy for observing
planktonic microorganisms.  Ann. Inst. Oceanogr. Paris.  58S:261-266.

Stoecker, D.K., D.J. Gifford, and M. Putt.  1994.  Preservation of
marine planktonic ciliates: losses and cell shrinkage during fixation.
Mar. Ecol. Prog. Ser.  110:293-299.

Verity, P.G. and M.E.Sieracki.  1993.  Use of color image analysis and
epifluorescence microscopy to measure plankton biomass. In: (Kemp,
P.F., B.F. Sherr,E.B. Sherr, and J.C. Cole, eds.)  Aquatic Microbial
Ecology.  pp. 327-338.  Lewis Publishers, Boca Raton.