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SOP7 – Live Organisms >50 μm
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measure an organism’s length and capture the information to an image (JPEG) file. The software
measurement tool is calibrated once a year to a NIST certified micrometer for each scope
magnification level.
8.2.1. Treatment Samples
Samples of the >50-µm size fraction are to be transferred from the cod-end of the net to a large
beaker/small-pail (6 L minimum), made up to volume >3 L, and put on aeration. The treated
discharge sample is examined for presence of live animals. The sample may be divided among as
many sorting trays consecutively processed as required to maintain adequate visibility
(acceptable density of debris and biota). In other words, if debris should obscure visibility too
much then sample must be spread over more trays to be processed.
Categorize live animals by coarse-taxa or species as most convenient. Larvae and juveniles are
identified to extent time allows but generally not to species. Live analysis must be completed
within three hours of when the sample was taken. Do not waste time on precise ID’s. These may
be obtained later from fixed samples (Section 8.3). Animals appearing sedentary or immobile
but not obviously dead (severe damage or decomposition, empty shell, etc.) should be nudged
with the probe to test for response. Time constraints dictate that dead animals do not need to be
counted unless they are quite few and will not take up much time. Make notes regarding any
animals: 1) ambiguous with regard to size-class and 2) ambiguous with regard to live/dead
status. For example: presence of immobile, otherwise intact and whole bivalve veligers is
recorded as ambiguous. Note that if treated discharge sample has well over ten obviously live
organisms per cubic meter, status of ambiguous animals is perhaps not so critical to
determination of pass/fail. However, if there were 6-live and 6-ambiguous, then it would be a
quite important distinction to consider and clarify to extent possible. Record the counts and notes
on zooplankton live-assay data-sheets, initial and have QA/QC checker review and initial.
The treated uptake sample is transferred to a large beaker/small-pail (6 L minimum) and made up
to a volume of 3-L. To subsample, agitate appropriately (via random motion stirring) with
stirring plate and subsample 2 ml with Stempel pipette. This will result in a 1/1500 split; note
split and subsample volumes. Other splits/beaker-volumes may be used if too few or too many
animals are present; however, a 1/1500 split tends to be a good place to start. Aim for >200 but
<400 animals/tray. Place subsample in labyrinth sorting tray. Note all taxa present. Quantify
dead organisms only, but do so by taxa. Perform 3-replicates of this assay.
When treated sample analysis is complete, sieve/rinse with pre-filtered treatment water into pre-
labeled 500 ml wide-mouth Nalgene HDPE sample bottle. Continue to maintain separation of
equipment between treatment and control and only use filtered, treated water in processing.
Adjust volume in bottle to about 400 ml (the pre-filled 10 L carboy of filtered treated water is
used to refill squirt bottle) and fix with 45 ml full-strength formaldehyde to obtain 10% formalin.
Rinse and clean all equipment that has been in contact with sample or ambient water with
freshwater prior to placing in storage. If any questions of taxonomy have arisen, they may be
addressed at leisure using the fixed samples, which will be kept on archive at least until reports
have been finalized.