MicrobeHunter.com Microscopy Forum

This is a continuation of the recent thread "More Critters From The Plankton Net": viewtopic.php?f=6&t=15089&sid=27d548bb5 ... 542ec456f3

Several of us got into a discussion of plankton nets, specifically the relative merits of "store-bought" vs. DIY nets, and reviewing those nets we've actually used. This led to the subject of the Nitex® mesh fabric used in the WILDCO Fieldmaster 8" net I recently purchased, in which I said:

"I can't recall where I saw it, but I seem to recall that Nitex® is first woven, then heat pressed to fuse the fibers. It doesn't look like typical woven material under the microscope, so I think this is correct. At any rate, one of the things I like about it is the fabric rinses easily and cleanly, which means it "releases" the critters into the receptacle quite nicely, much better than my other nets of "lesser" mash fabrics. Back home it cleans up perfectly back to snow white in the kitchen sink, and doesn't require "blasting" with the hose outside like my others."

Well, there's some technical literature on the web to be Googled up, but it's said that a picture is worth a thousand words, so let's just look at some photos instead. Also, I wanted to start a thread dedicated to Plankton Nets for the benefit of future searchers rather than bury in the back of my images thread. So here we go...

Whoops, one more thing first. All pix were made on an Olympus BHT BH-2 through the Splanapo 4/.16 objective using partially crossed polars in the light from below, and a bit of LED lighting from above.

Image 1: The Geosafari Plankton Net was sold as a kid's toy (pretty cool "toy" if you ask me) which, after modifying with a better collection bottle, was great for collecting plankton samples. This is the fabric, and you can see dirt caught in the many fibers that strongly suggests the number of wee beasties that might've been caught in this net, but never got out alive. Besides that, it was a pain to clean.

Image 2: This is filter fabric from the local swimming pool supply store. I forget the size, but it is sold in mesh sizes, and makes a pretty decent homemade net.

Image 3: Here's the Nitex fabric. 'Nuff said, I think...

Hi Kurt,
good idea to start this thread! A plancton gives access to the huge range of objects to be found in water. At the same time plancto nets are not something one can buy in every department store.

For plancton collection I often use the sieve shown here. The stainless steel 50µ mesh can easily be welded to the plastic tube with any hot object like a soldering iron or a wire heated above a gas flame. The welding is done by touching the mesh, not the tube. One has to place the mesh over the tube and first spot weld the four corners, then continue on until all is welded. Ideally one takes tube for which a fitting container is available. Here I used a plastik beaker but most of my sieves are made from plastic sewer pipes (HT - Rohr in Germany). The collection is done by pouring a few dozens of liters through the sive by means of the outer container. The collection bottles can be stored in the sieve, the sieve in the container.

The sieves can be used to concentrate plancton and small sieves on a stick can be used to collect samples from the walls of plancton aquariums.

I also show a few meshes, two of store bought plancton nets of about 90µ mesh size, two of printing mesh from Aliexpress. Ideally a mesh should have square openings and fine mesh fibres and be robust at the same time. Double strands of fibres are not ideal as they tend to hold back dirt. One of the Aliexpress meshes has nice square openings but the mesh size is a little big at 150µ.

Bob

Thanks for covering so much of the subject.
How to fit all the projects in,a sewing machine attracts more sewing machines I know that much.

I don't get it.....

A "net" is made to collect something, or, in this case, to catch everything larger than the opening size, and let the smaller stuff pass through, I imagine.

What I don't understand, is how the passed plankton flows into the collection bottle. Is there a screened opening at the bottom of the bottle that allows for flow?

That's a good question. What happens is that anything/everything larger than the mesh openings gets captured in the net, right? At the end of the drag, the net is raised slowly out of the water, and the collected 'stuff' eventually ends up sinking into the bottle at the bottom. So the key phrase is 'the net is raised slowly', whereas the collection bottle isn't necessarily filling up with specimens as the net is trawled, but receives the catch when the net is hauled up.

It actually would increase the performance of the net when there were a screened exit at the bottom. But in practice when there is a great plancton concentration at the entrance of the bottle it will be good inside. I like it to have more than one bottle and some lids and this would be difficult to have in multiple examples.

Has anyone ever tried to concentrate a plankton collection sample with the use of a field centrifuge?

I suspect I might get questioned by TSA as I try to re-enter the country with a few gallons of seawater....

Sure Squintsalot wrote: ↑

Wed May 18, 2022 7:02 pm

Has anyone ever tried to concentrate a plankton collection sample with the use of a field centrifuge?

I suspect I might get questioned by TSA as I try to re-enter the country with a few gallons of seawater....

I have no person experience, but I have read that centrifiging can cause significant damage to the plankton.

dtsh wrote: ↑

Wed May 18, 2022 7:35 pm

Sure Squintsalot wrote: ↑

Wed May 18, 2022 7:02 pm

Has anyone ever tried to concentrate a plankton collection sample with the use of a field centrifuge?

I suspect I might get questioned by TSA as I try to re-enter the country with a few gallons of seawater....

I have no person experience, but I have read that centrifiging can cause significant damage to the plankton.

That is correct, if centrifugal force is too strong (speed is too high).

We can simply let gravity settles down subjects. Yes, some loss is expected, but the I believe benefits outweigh the cost (of carrying a centrifuge - even a manual one can be bulky).

I'm thinking about those hand cranked centrifuges you might see in remote medical centers. But if elevated g-forces are likely to damage plankton, maybe overhead spinning on the end of a string might be too much as well. I'm surprised they survive passing through all of the collected debris in a plankton net!

I see plenty of damage, especially to planktonic diatoms which tend to have lots of long spines, just getting them to a slide and placing a cover slip. Yes, I know, there's always the inverted microscope...

On the seashore...My old women's veiled stockings with frame in garden watering hose and nylon strings.
They also do the trick.
Thanks Kurtm I wondered how this was possible.

MicroBob wrote: ↑

Sat Mar 12, 2022 8:13 am

For plancton collection I often use the sieve shown here. The stainless steel 50µ mesh can easily be welded to the plastic tube with any hot object like a soldering iron or a wire heated above a gas flame. The welding is done by touching the mesh, not the tube. One has to place the mesh over the tube and first spot weld the four corners, then continue on until all is welded. Ideally one takes tube for which a fitting container is available. Here I used a plastik beaker but most of my sieves are made from plastic sewer pipes (HT - Rohr in Germany). The collection is done by pouring a few dozens of liters through the sive by means of the outer container. The collection bottles can be stored in the sieve, the sieve in the container.

I like this technique - where can you find stainless steel meshes appropriate for this?