Bad sand samples

[Dale]

It looks like my beach sampling method was wrong. I scooped the wet surface sand as soon as the
water receded. I got a cup every other minute, and a good dousing in between! However no diatoms
are showing up. How should I do this in the future?
Dale

[lorez]

For my needs the diatoms are not necessary. Just dry the sand well.

lorez

[zzffnn]

Dale,

What diatom harvesting method did you use? If you followed my protocol exactly, then your sample may not have enough diatoms, which is probable.

It depends on tide, season and luck. Like I said, of my 15 lbs of sand collected from 5 different locations, only 0.5 lbs collected at one location has sufficient diatoms. So if I did not collect at that location, I would have come back empty handed.

There is nothing special as to collecting sand, as long as you scoop submerged wet surface. The key is to collect at multiple sites.

Let us wait for Rod and see if he can put some magic into your sand sample.

Maybe collect more at different locations (say, 6 miles apart) next time. There is always next time........ Don't be too hard on yourself.

What temperature was it there at Maui? I assume pretty warm? Some say diatoms come up more in March - August, but it depends on temperature and sunshine.

[zzffnn]

Dale,

I forgot to say that although my diatom-rich sand sample has been used up by me/Kurt/Rod, I still have some interesting Pensacola sand samples for you:

1) a sample with macro shells; and

2) two samples (from two locations) that have some diatoms, but in very limited quantity/density.

I can send both to you. Just let me know (by PM) your shipping address.

[rnabholz]

Hey Dale,

Got your package, thank you.

I washed the sample using the same technique that I usedbon the Pensacola sample.

Sorry to report that is is darn near diatom free. Really very few in the sample at all.

I certainly have been there, I have whiffed more than once.

I appreciate your trying, and will help in the future if you want to give it another try sometime.

Rod

[Dale]

That is what Charles reported. I scooped right from the surface as the surf flowed
out, which I guess is wrong. Next year, at Kauai, I'll be better informed, and prepared.
Do you agree that I should stay well above the surf line and dig down?
Dale

[rnabholz]

Being here in Iowa, I will defer to those with more experience with the marine environment.

Zz mentioned that better luck may be had looking for "dirty" sand, so digging down some may capture more trapped material than the top layer that is well rinsed.

Please wait for those with more experience than I bring to the subject.

[Charles]

That is what Charles reported. I scooped right from the surface as the surf flowed
out, which I guess is wrong. Next year, at Kauai, I'll be better informed, and prepared.
Do you agree that I should stay well above the surf line and dig down?
Dale

I tried a couple of times and still haven't seen one diatom...thought I saw a centric, but was chasing an air bubble. But no worries. We really appreciate your efforts. The best areas...would probably be around the high tide line down deeper for diatoms and on the surface for foramin. It probably also depends on the season. Hawaii had a few typhoons come through and maybe they replenished the sand...like they do around here for the tourist beaches. Practice on the sands and waters of the Puget Sound. Look for things that are hanging out in the water...rocks, vegetation, ropes, cans, bottles or even get a plankton net and zoom around the sound with it. You be able to see what you are into if you took a small portable microscope with you to verify there are diatoms

[zzffnn]

I think the key is to collect at multiple locations miles and day/night apart, if possible. Tides / season change things around too. March to August is better time to search for diatoms.

I am not sure this is always true - but I found my Pensacola diatoms in surface sand that is ALWAYS submerged under water. Sorry, if I was not clear previously.

[zzffnn]

I like the sand, thank you, Dale! I am sure Kurt will like it too (I will pass on half to Kurt).

I did a careful high volume screen of the Maui sand (I concentrated wash water of around 30 ml of sand and also looked at the big mineral particles).

At macro size bigger than 0.5 mm, the mineral particles look quite interesting under 4x objective (and reflected light). I saw different colors and mineral inclusions. Some white particles look like they came from living organisms (but I am not sure and could be wrong).

At particle size of 500 microns and less, under 10x objective, I did not see many interesting things. 1 foram and 4 interesting diatoms of reasonable size stood out. There were maybe around 60-100 super tiny diatoms of limited variety. Maybe October is not prime diatom season for Maui? Just a guess.

[Dale]

Well, from 2018 on we are going in April and October, and I will start diving for sand. My scope
man is conjuring up some portable scope options. My only use for one would be scanning samples right
at the beach. My first guess is something like this: monocular, 10X EP, 40X OBJ, no understage parts,
oblique and/or substage mirror for lighting. Once I have good sand to practice scanning I'll be able
to refine my needs better.
Dale

[zzffnn]

Well, from 2018 on we are going in April and October, and I will start diving for sand. My scope
man is conjuring up some portable scope options. My only use for one would be scanning samples right
at the beach. My first guess is something like this: monocular, 10X EP, 40X OBJ, no understage parts,
oblique and/or substage mirror for lighting. Once I have good sand to practice scanning I'll be able
to refine my needs better.
Dale

I would suggest additional 10x obj., 20x obj., condenser and a battery power LED / headlight / flashlight. Sometimes you may remove mirror and put LED directly under condenser. DIY darkfield and oblique stops will help too.