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Subscribe to this list via RSS Blog posts tagged in Diatom

Posted by on in Microscapes

In an earlier post I asked why certain diatoms moved when they had no need to search for food and no need to find a partner to reproduce. A recent enquiry to the 'Amateur Diatomist' website has resulted in this very informative reply:

"Lots has been written about the mechanism of diatom motility but little about why they might need to move. Whilst I am not qualified to explain all the reasons for their behaviour a couple of observable examples might suffice to set you on the right track....

Consider the episammic (living on sand) or the epipelon (living on mud) species where their habitat is governed by the tides. When the tide is in the diatoms can be found on the surface of their chosen substrate, when the tide goes out they are found within their substrate. They have moved to ensure they do not dessicate. Another example are those species found living on rocks in streams. They coat the upper surface of, say, a pebble. Should a storm suddenly cause the flow to increase to such a degree that it turns that pebble the diatoms will move to upper surface when things quieten down. This latter example can be observed by turning a colonised pebble by hand and returning the next day.
 
I hope these simple examples provide you with an answer (at least in part). Steve."
 
For anyone interested in diatom studies you'll find lots of useful information on the Amateur Diatomist website. www.diatoms.co.uk
Tagged in: Diatom Environment
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Posted by on in Microscapes

The next installment of the Diatom Survey should be along in the next few days. While you're waiting for it to arrive, here's a little video that is not only entertaining, but I think is also rather thought-provoking.

Diatoms are single-celled organisms that get their energy from the Sun via photosynthesis, so they don't need to hunt for food. If they don't live in colonies where they attach to others of their kind they don't need to search for friends. They reproduce by binary fission, dividing into two daughter cells each with one half of the diatom shell and each daughter then makes the other half for itself, so they don't need to search for a partner.

So why do diatoms move? Even though their meanderings do seem rather aimless there must be some reason for it, but I admit, I cannot come up with a sensible suggestion for it. Perhaps you can. If you know, or find out, then please feel free to contact me: This email address is being protected from spambots. You need JavaScript enabled to view it.

Here are a small collection of motile diatoms. Enjoy.

 

Tagged in: Diatom
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Posted by on in Environment

We have just completed the most recent round of surveying for Midgelden Brook and are pleased to report that some signs of life have returned to Site 1 (opposite Woodlands View). You can view the updated results in chart form here:-

Invertebrate Survey Results

Samples have also been taken for investigation of the Diatom population as part of our proposed quarterly study. We must thank the Environment Agency for their help with resources relating to Diatoms, and also to JK for preparing the samples and attempting to perform basic identification.

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Posted by on in Microscapes

This post comes a little earlier than expected due to major technical problems with Wal's computer. The diagnosis is "Klingon Nuclear Accelerated Cyclonic Kinetically Excited Radiation Emitting Disorder" (KNACKERED). The computer is also broken! Treatment and repairs are underway and we hope for a speedy return to blogging. :-)

The idea of a 'dress rehearsal' for the diatom study proved to be a good one. It highlighted a number of items that were useful: different equipment to produce better/easier ways of doing things; an indication of the time and effort required (which is considerable); which procedures work best in the laboratory, and so on. All these things have now been dealt with, and one or two minor problems solved, so we can now begin the study in earnest. That said, we can at least confirm that there are diatoms in Midgelden Brook as we would expect, but it's nice to know we can find them even if we can't yet name them. (Click image to enlarge)

Dry samples are better than wet ones; bleached, washed, dry samples are even better. The prepared slides (like those above) gets rid of all the organic 'gunge' that clouds the image and often hides the diatoms. What remains are the mineral fragments, which are quite pretty I think, and the diatom shells that we are searching for. In future I hope to make permanent slides of our best finds, but this involves using Naphrax as a mountant and is something that is best left until I am more proficient at everything else. The solvent used in Naphrax is Toluene, which is dodgy stuff, so I want to be confident I can use it safely.

On a more positive note, my stage micrometer should arrive tomorrow and over the next day or so I'll be able to calibrate my microscopes at all magnifications so that I can take very accurate measurements of specimens and include them in the images with the correct units attached. At the moment I'm only able to measure in pixels (px) so I'm really looking forward to my new toy. With my newly aquired knowledge of callibration, layers, measuring and text tools, you'll hopefully be seeing images like this:

b2ap3_thumbnail_pixels-label.jpg

I've started work on my 'Recording Sheets' so that I can keep track of dates, pH levels, number of specimens, etc., so that in years to come we can track any changes that occur and make comparisons between the invertebrate study and the diatom study. I'm only able to record pH in steps (pH 6, pH 7, pH 8, etc) but at least I'll be able to note any major events in that department.

As to the number of specimens in each sample, I've devised a 5-point system which again should provide useful if not precise data to work with, bearing in mind that this study is a learning exercise and needs to be enjoyable rather than scientific. ;-)

1. NONE: Micro-life may be present but was not observed.
2. RARE: Very few specimens throughout the whole sample.
3. SCARCE: Small number of specimens scattered throughout the sample.
4. COMMON: Several specimens in many areas of the sample.
5. ABUNDANT: Numerous specimens in most/all areas of the sample.

SO LET THE GAMES BEGIN ... ;-)

Tagged in: Diatom Microscope
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