Posted 09 May 2008 - 15:08 PM
So, I'll start this thread to address these common misconceptions and dispel myths around them. - Rich
Posted 09 May 2008 - 16:58 PM
Edited by jimscott, 09 May 2008 - 18:41 PM.
Posted 09 May 2008 - 19:47 PM
Although the smaller semi-tropical red forms can be kept alive in container growth for some time, they always pale in comparison to the very same strains that are grown in pond like conditions; it's nearly impossible to emulate all the complex relationships this plant has with other organisms in its natural environment. At best, it's extremely labor intensive and expensive. Then there's the realities of how fast it grows when it finally does achieve prime conditions. Imagine someone asking a similar question such as: "What size terrarium do I need to grow N. bical, N. raff, N. rajah, or N. lowii?"
Although the individual strands are themselves small enough to be contained in an aquarium, the rate of growth of the population, as a whole, needs to be considered. They grow exponentially; during their peak months, from the end of June to late October (about 18 to 20 weeks), they will double their population every week, perhaps even a little more in more favorable conditions. To put this in context, I asked my son the following hypothetical question, (one that I heard when I was a kid):
Imagine if one day, a very wealthy person asked you to do a specific job, a task that would take exactly 30 days, and it was well within your ability and means, but with the following salary options: Plan A: A flat rate of a thousand dollars per day worked, or Plan B: A single penny the first day, twice that the next, for two pennies, and twice that for 4 pennies the next day, and so on, doubling the amount with each day worked; (and your option to work all 30 days in one stretch, or take two days off every five days, for six weeks).
Which salary option would you chose? My kid took a few minutes, putting up one finger after another until all ten were used and said: "Hey Dad, after ten days, all I get is $5.12! I'm going with the thousand dollar per day plan. I handed him a pencil and paper and asked him to continue the calculation to day 30.
After few minutes, he quietly blurted out a "Whoa!" and said "By day 27, I'm a millionaire!" and that's just for that one day's pay!", the sum total will be one penny less than tomorrow's paycheck.
So, with that, imagine all the Daphna, and zooplankton such a population would need to sustain itself, not to mention the size of such a container to accommodate them all, and the source of CO2. It's not just a few plants, in growing Aldrovanda, but it's a population that needs to be considered.
Posted 10 May 2008 - 02:54 AM
Essentially, it's not the chemistry of the water, but it's the biology that makes the difference.
I recall many years of going through the various attempts at making "tea" and other broths with peat, leaf litter, even using CO2 generators, various attempts to lower the pH with vinegar (acetic acid), even sulfuric acid, tannic acid, and all, thinking that the chemistry of the water needed to be perfected, and each time ended in failure when the inevitable filamentous algae took over.
My pond water tests moderately hard, and neutral pH (7.0). The water depth in which the Aldrovanda grows best is only ankle deep, littered with leaf litter, and densely packed with hummocks of large monocot plants (including a Phragmites bed), that produce massive root systems, and the Aldrovanda strands grow only a few inches above them, or nestled in with those roots when they get exposed. There is a conspicuous absence of algae, in fact algae goes into decline in the presence of healthy Aldrovanda strands.
There are areas where the water depth drops quickly from ankle deep to waist deep within a short distance, and the Aldrovanda refuse to grow in those deeper areas, even though the temperature, the chemistry and even the exposure are exactly the same, the only difference is the proximity to the live root systems, and the population density of the zooplankon community, which is the highest in shallow areas.
Aldrovanda requires a constant supply of CO2, which is produced by these massive root systems from respiration, coupled with the active zooplakton community, and the rate of respiration increases with the temperature. CO2 and prey are essential to their growth. CO2 out-gases very quickly, and becomes ineffectual in depths over a foot deep.
After walking through the pond, my boots churn up the bottom silt and debris to the point where I can hardly see the strands anymore. The water goes from a clear quality to a disgusting soupy slurry of detritus, silt, clay and thin mud. After a few days, some strands get weighed down by all the sediment, and are growing back up from the bottom. I also notice that these strands seem to take a quantum leap in growth from those other strands that have been growing in undisturbed waters. So, as for water "quality" I say the dirtier, the better!
I'm convinced that Aldrovanda is a constituent member of a complex symbiotic relationship involving several other plants and organisms, including copepods, and other crustaceans, mollusks, insects, and the other creatures of the zooplankon community, and cannot live well for long without the close and intimate proximity those other members of this special niche. Small snails pull out the spent carcasses from the older traps before they get full of filamentous algae, and often wind up as food for the Aldrovanda as well.
I took a small sample of this "ankle deep" water, where the Aldrovanda grows best, brought it to my son's high school, and looked at it under a dissecting microscope. The water seemed rather clear to the naked eye. But when viewed under a 30x lens, it was like sprinkling pepper onto a dinner plate, and all the flecks were moving, with an occasional snake or two making a cameo. The water is teaming with life.
Edited by rsivertsen, 10 May 2008 - 02:57 AM.
Posted 10 May 2008 - 18:15 PM