Counting cells in the field?

Walter K Dodds wkdodds at
Fri Sep 16 12:46:33 EST 1994

The problem with counting these species directly is that Nostoc
is very difficult to disperse evenly.  It has a very gelatenous
sheath, so subsampling would be out of the question.  On the other
hand it is large enough that it could be picked out by hand and
counted or weighed seperately.  The less tighly aggregated species may
be scraped from a known area and dispersed evenly (possibly with
gentle sonication and a tween 80) and a subsample counted directly.
One thing that is good with cyanobacteria, they are probably the only
group of bacteria that can be assigned to genera under the micrscope
without culturing.  Direct counting is a time honored technique
(but time consuming) for determining relative biomass within complex
communities of algae.

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