VPP 322: Aquatic Animal Diseases, Health Care and Management (1+1)

COLLECTION AND PRESERVATION OF PHYTOPLANKTON FOR QUALITATIVE AND QUANTITATIVE STUDIES

• By net method, only phytoplankton of >50µm size can be collected. Nylon material of No. 30 (pore size 51 µm) is ordinarily used for the construction of various types of nets for the collection of phytoplankton from surface and at different depths. 

• For the differential collection of phytoplankton samples from the surface of fish ponds, a known quantity of water, i.e. about 500 ml is filtered through a conical bag made of No.30 bolting silk net. A graduated bucket is used for this purpose. The plankton so filtered in this net is concentrated and is considered mainly for quantitative analysis
• For preservation of net phytoplankton, 2% neutralized formalin is used. The volume of the supernatant preservative should at least be equal to the settled volume of plankton. 1000 ml of 2% neutralized formalin is prepared by diluting 50 ml of 40% formaldehyde solution with 950 ml of filtered seawater, to which 0.5 g borax (sodium borate), 6.5 g of disodium hydrogen phosphate are added and the solution is allowed to settle for about 24 hours. The supernatant solution is siphoned out and used.