I am taking my students to collect water samples from different bodies of water. These bodies of water include the local river, a park pond, and water accumulation from recent rain. Once we gather the samples students will be analyzing the samples under standard light microscopes. I was wondering what is the best way to preserve any life that may be found in the samples in case there is no immediate opportunity to analyze the samples under the microscopes? Is there a specific time frame to analyze the samples before they have to be replaced? Also if they are kept in a bottle/jar does the container have to be unsealed or with perforations to allow air flow? Thank you.

  • $\begingroup$ What sort of timeframe? Collect in the morning & analyze in the afternoon would be good. Next day? Next week? Next month? $\endgroup$ – Solar Mike Aug 14 '19 at 5:23
  • $\begingroup$ The samples will be analyzed within a week. Collection will take place Monday and the analysis of samples no later than the Friday of the same week they were collected. $\endgroup$ – Jeb Aug 14 '19 at 14:19
  • $\begingroup$ Things start changing in minutes in sea water: I picked this up from some book on salt water aquariums when I had them.. I can tell you delicate inverts start dying in one day when power failure shuts down the circulation pumps although battery powered air pumps are running. The main reason I gave up on salt after about 15 years. $\endgroup$ – blacksmith37 Jan 14 '20 at 3:40

Depending on what you are trying to look at, for zooplankton you can take water samples and filter them through a 100-200um mesh and store them in glass or plastic bottles. For my research we used mason jars that were cleaned thoroughly. After filtering just submerge the biomass in 70-90% ethanol and they can be stored in a fridge for quite some time.

If you want to look at phytoplankton, you can look into using Lugols Solution for preserving your samples. The nice thing about using lugols is that it will stain the phytoplankton as well. Your best bet for these is to store in amber bottles and keep in cool dark place. Here is a decent guide on how to collect the samples and prep the solution.


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