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Old 04/02/2016, 07:22 AM   #3474
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Join Date: Mar 2010
Location: NE Miss
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Originally Posted by taricha View Post

5. I also pulled the few dinos out of my tank and split into beakers. Mix of small amounts of both amphidinium and ostreopsis The population in my tank is small but stable at the time I pulled it out. One beaker got nothing added, one got iron, one b12. Hoping for dramatic growth in one of the treatments indicating a limitation.
Some results. Interesting, perplexing, and not a slam dunk.
100ml in each beaker, the iron treatment was 2 drops of a solution containing 0.10% Fe edta (and 3% K - but my tank already gets dosed a ton of K so it's definitely not limiting). About 100mcg Fe (3mg K).
The B12 dose was 1/10 by mass of a ground up 1000mcg B12 pill. About 100mcg B12. Placed in bright window.
Remember all these are taken out of my tank which I'm keeping at high N and P (20 and 0.50ppm respectively) so micronutrient effects can be seen.

So after 1 day, there were a ton of bubbles in the B12 treatment indicating increased photosynthesis. No other obvious differences to naked eye. Under scope the cell counts were different but not enough to be sure of anything. After 2 days same story about bubbling. this is what they looked like


B12 note bubbles

I would have assumed massive dino increase in B12 and little change in others from bubbles and sample coloration. But it's a good reminder don't presume what you didn't actually observe.
Cell counts under scope. All beakers got equal mixing, sample sizes, magnification etc. Largest number of dinos in a single 40x field of view for each sample was:
  • Control: 3 dinos
  • B12: 28 dinos
  • Fe: 61 dinos

Make of that data what you will. I'll watch same beakers a couple more days to follow progress, and I started the experiment again to see if results are repeatable.
Here's my take. Control population seems to have decreased in the 48 hours in the beaker. likely division was slower than predation. Probably due to trace element limitation. Matches the small steady population in my tank. Just enough micro nutrients trickle to it to through fish food to keep it a light dusting.
B12 definitely increased photosynthetic output, and also seems to have juiced cell division somewhat.
Fe showed greatest increase in dino numbers, clear response.
If I'm hypothesizing, it seems like the B12 increased photosynthetic metabolism so to speak, but I can't help but feel like this would be short lived and cell division would soon slow unless the Fe limitation shown from the other beaker was addressed.

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