Dataset: Biomass
Deployment: AT11-30

Methods for Phototrophic and Heterotrophic Plankton Taxa Sampling, Preservation,

Enumeration and Biomass Estimation

(Modified from Frame and Lessard, in press)



Biomass of phytoplankton and microzooplankton taxa groups was measured in the initial samples

for dilution experiments off the Washington coast taken during six ECOHAB PNW cruises 2003-2006.



Replicate samples for phytoplankton and microzooplankton identification, enumeration, and sizing

were preserved with either acid Lugol's (5% final conc.) or gluteraldehyde (0.5% final conc.).

Gluteraldehyde-fixed samples were stained with DAPI and proflavin, then filtered onto 0.8µm and

0.2µm black polycarbonate membranes (Lessard and Murrell 1996). Slides were stored frozen until

analysis onshore.



Microscope counts

Known volumes of the Lugols-preserved samples were settled in counting chambers for enumeration of

ciliates (including mixotrophs), diatoms and larger dinoflagellates. Counts were performed on a Zeiss

inverted microscope at 250x magnification. Glutarldehyde-preserved samples on 0.8µm filters were

examined with a Zeiss standard epifluorescence microscope at 400x magnification for enumeration of

microphytoplankton including photosynthetic dinoflagellates (typically
an unidentified raphidophyte. Samples on the 0.2µm filters were examined at 1000x magnification for

cyanobacteria, picoeukaryotes (2-10µm).



Biomass estimates

Picoplankton (cyanobacteria and picoeukaryotes) were sized using images taken with a QImaging Retiga

EX charged coupled device (CCD) camera and Image Pro Plus software. Dimensions of all other cells

were measured using a computer-aided digitizing system (Roff and Hopcroft 1986). Cell volumes were

calculated using appropriate geometric formulas and carbon was calculated using the carbon to volume

equations of Menden-Deuer and Lessard (2000) for diatoms, nanoplankton and dinoflagellates, and of

Worden et al. (2004) for picoplankton. Ciliate carbon was estimated using the conversion from Putt

and Stoecker (1989).





References for further details:

Lessard, E.J. and M.C. Murrell (1996), Distribution, abundance and size composition of heterotrophic

dinoflagellates and ciliates in the Sargasso Sea near Bermuda, Deep Sea Research Part I, 43(7), 1045-1065.



Frame, E.R. Frame and E.J. Lessard. Does the Columbia River Plume influence phytoplankton community

structure along the Washington and Oregon coasts? In press. J. Geophysical Res.



Menden-Deuer, S., and E. J. Lessard (2000), Carbon to volume relationships for dinoflagellates,

diatoms, and other protist plankton. Limnol. Oceanogr., 45, 569-579.



Putt, M., and D. K. Stoecker. 1989. An experimentally determined carbon:volume ratio for marine

"oligotrichous" ciliates from estuarine and coastal waters. Limnol. Oceanogr. 34: 1097-1103.



Roff, J. C. and R. R. Hopcroft (1986), High precision microcomputer based measuring system for

ecological research, Can. J. Fish. Aquat. Sci., 43, 2044-2048.



Worden, A.Z., J.K. Nolan, and B. Palenik (2004), Assessing the dynamics and ecology of marine picophytoplankton:

the importance of the eukaryotic component, Limnol. Oceanogr., 49(1), 168-179.