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SOP8 – Live Organisms 10-50 μm
65
Total area (TA) is the total viewable surface area of the counting chamber, it is calculated by the
equation 1.
TA = π(x)
2
(1)
Area of field (AF) is the area visible through the microscope in one “field of view”, it is
calculated by equation 2.
AF = π(r)
2
(2)
This translates to number of fields available on the counting chamber by magnification and is
used when doing ‘point counts’ on the chamber. Select 20 random fields of view/magnification.
Use this method only for total phytoplankton (dead) counts.
Calculate number of fields using equation 3.
Number of Fields =
!" !"
(3)
Magnification
Field of View
X
(mm)
TA
(mm
2
)
r
AF
Number of
Fields
100 x
-
10x objectives
-
10x oculars
22 units x 0.1 mm
= 2.2mm diameter
9.57
287.7
1.1
3.80
76
200 x
-
20x objective
-
10x oculars
11 units x 0.1 mm
= 1.1mm diameter
9.57
287.7 0.55 0.95
303
400 x
-
40x objective
-
10x oculars
5.5 units x 0.1
mm = 0.55 mm
diameter
9.57
287.7 0.27
5
0.237
1214
Cells per mL formula =
!"# !"#$% (# !"#$%& !" !"#.!"#$%&#%)
# !" !"#$%& !"#$%&'
/ volume settled
9.8. Site Validation for Viable Phytoplankton Analysis
The CMFDA/FDA test for viability of phytoplankton needs to be validated at each site being
tested. Accuracy of the stains vary by geographical location and taxonomic composition of the
planktonic assemblage. (Steinburg 2011). False positives can occur and the population needs to
be tested with both live and dead samples.
(detailed in Steinburg et. al. Mar Biol (2011) 158: 1431 – 1437)
9.8.1.
Sample Collection
1.
Collect 3 – 500 mL Whole Water (WW) samples with Niskin/Kimmerer bottle below
surface of water at site where BWT system testing will occur
2.
Samples should be collected in amber Nalgene bottles and placed in cooler for return to
the laboratory