Cook Plant preoperational studies 1970 / John C. Ayers ... [et al.].

Previous phytoplankton samples collected from water of brownish-green
color indicate (at least to the extent that the same analyst had not previously
noticed this dinoflagellate) that the organism has not before been present in
our samples.
From this we do not conclude that noxious blooms of this algal form are
an immediate threat. We do, however, conclude that the presence of one more
algal form capable of producing nuisance blooms cannot be indicative of improving
water quality in the lake.
A.3 Development of a Monitor for Phytoplankton
In response to a very pressing need for a more rapid way in which to
assess the numbers of living phytoplankters in the water of Lake Michigan, we
attempted a direct attack upon what amounts to two problems simultaneously.
We continually need to know, rapidly, the numbers of phytoplankton in any
given area of lake water. Particle counters can count the numbers of particles
passing in a stream of pumped water; they cannot, however, differentiate between
live phytoplankton, long-dead phytoplankton, or simple particulate detritus.
Live phytoplankton, or phytoplankton so recently dead that they still retain
their chlorophyll, will fluoresce under ultraviolet light.
We thought, and still think, that a workable means of counting passing
fluorescing particles in a stream of pumped water will provide some relief from
laborious microscopic counting of phytoplankters (with no way of telling which
are dead).
A counter of passing fluorescing particles was conceived of as being a
small chamber on the stage of a microscope provided with substage illumination
with ultraviolet light while the top of the microscope's optical tube was
equipped with a photomultiplier and an amplifier to provide needed signal
strength.

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