Field test for diatoms

[Dale]

Can anyone suggest a method for quickly analyzing beach sand for diatoms? I will have a microscope
of as yet undetermined properties. I am working on a mini-centrifuge, based on a very small cordless drill.
I have no nets or filters of any kind. Grateful for any help.
Dale

[zzffnn]

Dale,

Here is my exact screening procedure:

1) in a 15 ml tube, add 6 ml of sand and 6 ml water.
2) put a 200-500 micron pore sieve over a bigger petri dish.

3) plug the 15 ml tube, invert it 10 times and immediately pour out its content, over sieve/petri dish, right after the 10th inversion.

4) most sand sould be poured out, while some sand would remain in the tube. Add another 3 ml water, invert 5 times and pour out everything onto sieve.

5) immediately collect all water from petri dish and pour it into a clean 15 ml tube. Let tube sit for 5 minutes.

If you are in a rush, stop here, pour water into petri dish, then observe under 10x objective with darkfield or oblique light. For field work, no centrifuge is necessary. Let gravity work for you. Steps 6)-9) is not always necessary.

6) carefully remove ~10 ml water, from surface, using a ~3ml pipette. Then using a smaller fine tip pipette, carefully remove another 3 ml of surface water.

7) place the tube containing ~2ml water close to strong light. Using a fine tip pipette, take the bottom precipitate, but try to avoid big sand particles.

9) Dilute precipitates, if necessary. Then add sample to petri dish or flat bottom well slide to observe, under 10x darkfield or oblique.

You do need 2 steel sieves, one with around 200 micron pore size, one with around 400-500 micron pore size.

Here are some listings from eBay:

210 micron pore $9.95
http://www.ebay.com/itm/350819649632

381 micron pore $14.95
http://www.ebay.com/itm/221359719603

The seller Bennythestooge seems to know his sieve very well. Ask him if he has anything near 400-500 micron for cheaper. I got my 500 micron sieve for $1.5 from a kitchen tool store. His 210 micron sieve price is good.

Here is another 250 micron sieve for$9.29:
http://www.ebay.com/itm/391545771192

The 200-250 micron pore size will remove some huge and colonial diatoms, but it is helpful to remove tiny minerals and organic debris. The 400-500 micron pore size will pass through most diatoms but won't clean up sample as well. I think it would be nice to have both types. Steel sieve won't break and should last a very long time.

Without a sieve, you can try filtration with coffee filter or toilet paper. But those won't work as well. You need to reduce mineral particles and organic debris, as they may obscure diatoms, even in a live water mount.

[Dale]

Perfect, thank you. All printed out, and a copy to take to the beach. I needed a good link to calibrated sieve sites, thanks
for that also.
Now, the bad news. Next year we are going to be on the North end of Kauai, and my plan is to go to Humalai Beach
and collect olivine-flecked sand. Will the diatomist's be interested in that?
Dale

[zzffnn]

Dale,

I am interested in your Lumahai Beach / Kauai sand, even if it does not have diatoms. I will happily cover your cost.

The key is collect at multiple locations miles apart and between March to September.

Look for foam or brown oil drop like stuffs on beach, or scrape algae from rock surface, you may find some (or a lot of) diatoms:

http://www.seasideaquarium.com/diatoms_page2.php

https://www.niwa.co.nz/news/summer-seri ... beach-foam

Many places, including Mauai, have diatoms somewhere. It is just a matter of finding them:

http://www.schweizerbart.de/publication ... nd_120__no

https://www.researchgate.net/publicatio ... uai_Hawaii

[Dale]

I will have to see if there are any caves on the North side of the island. I really enjoyed those links, I understood
a lot of it. Filter mesh is on its way. We will only have a rental car for a day or two, so my collection time will be
quite limited, but I think I can get to a second beach easily. Do you think this book is ok: Diatoms of North
America, by Vineyard?
Dale

[zzffnn]

Sorry, Dale. I don't know about and don't have any diatom book.

I remember Kurt and Rod mentioned two books (whose names I cannot remember), though those are more for ID. It would be nice to have a book that have GPS coordinates of diatom collection sites (if such book ever exists). Rod also mentioned a Yahoo diatomist group. Maybe you can ask Rod or search?

[Dale]

Fan, I got a D in chemistry, because of making an explosive, still, with only a C I need help on some of the
lab supplies for the Diatom project. I have 2 slightly different protocols that I can resolve, but some of the tools
are a problem.
Pipettes: Do I need a .2ml, a 1ml, and a 3ml pipette? Research models are expensive, so could I use a 3ml graduated
bulb type for the different steps? Rinsing between steps.

Flat bottom well slides: There are so many kinds and types. How would a very small petri dish work? I
have been experimenting with them on my inverted scope, as full size petri dishes dont grip very well
in a moveable stage! They are expensive, but I have seen small, square, and inscribed petri dishes.

Water: Yes, water! When you say add water, do you mean fresh only, or if I'm at the beach can I
use salt water? I'm thinking the saltwater would not be a good idea because of all the sediment
and stuff that would be in it. So, I just bring a bottle of fresh water to the beach.

I think in a month I will make a big leap in expertise. The Nikon is working so well! Your advice is appreciated
more than you can know. I have been researching other methods of cleaning, and, well, most are quite
frightening.
Dale

[zzffnn]

Dale,

Any small fine tip pipette will work. I like this one with 0.01-0.1 ml adjustable volume: http://www.ebay.com/itm/172378964280

That volume range is most useful for us microscopists. If your hands are stable, you can pick up individual diatoms with that pipette's tip.

A small and thin plastic petri dish will work. I DIY my flat well glass slides with glue and credit card edges.

Any clear (salty or fresh) water will work.

[Dale]

Thaaaank you. I am all set.
Dale.