Respected sir/Madam expert working in field of algae and Diatom, I found following article on,
T. V. Ramachandra Malvikaa Solanki. 2007. "Ecological assessment of Lentic water bodies of Banglore. "
This is the formula for that, I found it, these is easy method for counting density of plankton. Can any body had reference of it.
i am using 25 (L) of water to collected in 50 ml bottler, and tanking 0.1 ml for sample for analysis on normal slide and cover slip.
Total plankton count per litre = A * (1/L) * (n/v) Where, A = number of organisms per drop L = volume of original sample (l) n = total volume of concentrated sample (ml) v = volume of one drop (ml)
Dear Roshan,
For the determination of diatom's density i suggest to make a cell count using a hemocytometer such as Burker chamber. With this tool you will make an accurate evaluation of cells density, expressed as Cells / mL.
Otherwise you could use a spectrophotometer, but in that case you should know at which wavelenght the diatoms absorbs and also the presence of other aquatic protist can influence your estimation.
The formula that you said seems not so accurate and precise to use, it requires anyway a cell count as i see.
Dear Roshan,
I suppose you need to count phytoplankton while identifyng species and counting them separatedly. This is what is usually required for biomonitoring and assessment of lenthic water bodies.
What is more widely used is the Utermöhl method, which requires having an inverted microscope. It's the best method to count phytoplankton and there is a norm (UNE-EN 15204) explaining it.
In case you lack it and have no choice to get one, I would better use the formula you said better than a Burker chamber, a Neubauer or something like that. I read that such type of chambers are useful, but when I have tried to use them I noticed that they were not (I had a Neubauer chamber). Water and some small cells entered in the small space properly, but big algae and colonies did not. For example, Fragilaria crotonensis, Ceratium, Volvox, etc. They got stuck and did not enter by capillarity between the two glasses. I think the method is perfect to count cells that are all equally small and all with the same shape (like red cell blood cells). But phytoplankton is too heterogeneus. That is my personal experience.
To avoid the same effect with your method, you shlould make sure that the pipette you use to take the test drop does not have a very fine entrance where large algae such as Ceratium, Pediastrum or Volvox would get stuck.
However, if you have the possibility of using an inverted miocroscope, it is the best solution.
Kindly check this paper.
https://apps.ecology.wa.gov/eim/help/HelpDocuments/OpenDocument/10
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