How to collect diatoms from sediment cores and how to fix for transport

[turtle1769]

Hi, 

I want to identify the benthic diatoms present in my sediment cores. To do this, I will need to collect and fix the diatoms in order to transport the samples back to my lab for identification as I am carry out field work overseas. 

Could anyone help to advise me how to:

1. Collect the benthic diatoms for the sediment surface of my cores?

2. How to fix the diatoms - probably using Lugols?

3. How to extract the diatoms from the sediment, should I do this before or after fixing in Lugols?

4. I will need to use a light micrscope to identify the diatoms. How should I go about doing this?

Thanks

 

[Peterkin]

Do you access to a centrifuge, or are you relying on sedimentation?

For long-distance transport, slides would be more practical than sediments. https://diatoms.org/practitioners/how-to-make-permanent-diatom-microslidesOf course, it depends on the sample size you want. 

If it has to be liquid, you might do better with ethanol as a preservative for long term, since it doesn't crystallize.

The microscopy is simple enough.

 

[turtle1769]

Hi Peterkin, thanks for your reply. 

I do have access to a centrifuge, would you recommend centrifuging the sediment samples and then fixing the supernatant hence, assuming that all the diatoms will be separated from the sediment? I am unsure whether I should also be looking into using the lens tissue method and whether these steps need to be done prior to fixation of the sediment samples. 

I unfortunately am limited in time so I will not have sufficient time to prepare permanent slides here but I will plan to do this on my return to my home lab. 

Would you recommend cleaning and washing the samples from the salt, as it is marine samples I am dealing with before preserving?