The other day, a reader of this blog pointed out in the comments section that "the water has become clearer."
First of all, in this 1-ton mini-earth "Biocube," I first put in a whole bottle of gardening Hyponex, then added the green water seed water, and about 50 liters of "Platinum Soil," which probably has nutrient runoff, so preparations began with the water in a state of extremely eutrophication.
Soon, a thick green water was produced.
Up to this point, everything was going as planned, but my plan was fragile and collapsed that the green water would soon become clear due to the exponential increase in the Daphnia.
The Daphnia had increased to a considerable number at one point, but soon a hydra outbreak occurred and suppressed the increase in the Daphnia.
If the water is too green, it will hinder observation.
In addition, the algae growing on the walls of the tank was also a serious problem.
So I introduced a lot of plants to fundamentally solve the eutrophication problem, and introduced a lot of freshwater clams and freshwater snails, which are good at filter feeding, as well as scaly snails and red ramshorn snails to eat the moss on the walls.
So, the green water became clear enough to make observations possible, and the moss on the walls was suppressed, so I was able to start the sealed experiment.
This happened about 57 days ago.
By the way, just before sealing the tank, I put a lot of fallen leaves in it, which also promotes eutrophication.
So I started the experiment and observation, and a reader pointed out to me recently that the water had become cleaner based on the photos I uploaded.
That's true.
I think the difference is obvious at a glance.
I mean, the The color of the water is brownish because of the fallen leaves, but it's no longer green water.
And the amount of algae growing on the walls of the tank has also decreased dramatically.
As for the snails, there are now fewer of them that are stuck to the walls and eating the moss, and the ones that are stuck to the underside of the carpet of aquatic plants like ninjas are more noticeable.
Let's compare the photos.
(before)
(after)
Whether the algae on the walls is clearly visible depends on the amount of light and the position of the focus, so it is not a simple comparison, but if this photo was taken from roughly the same position in the tank, it would be surprising.
What happened?
Currently, I think there are some major factors.
(1) I think the biggest factor was that the rapid proliferation of the aquatic plants eventually led to the amount of nutrients absorbed by the plants exceeding the amount of nutrients lost from the fish, shrimp, shellfish, soil, fallen leaves, etc., causing the amount of nutrients in the water to decrease and the water to become oligotrophic.
(2) Next, this may seem to contradict (1), but since I was preparing to start the experiment and struggling with the green water from spring to summer, it may be that the weakening of the excessive sunlight as winter came on was also a factor.
However, the room itself is kept at around 24°C and there is lighting in the room itself, so I think the amount of plants in the tank as a whole is continuing to increase.
Perhaps the light level is just right - not enough to encourage algae and phytoplankton to grow, but enough for aquatic plants to grow.
Well, for the Mini-Earth to be stable, just as the homeostasis of an individual living organism is maintained by a "negative feedback" mechanism built into the body, the "negative feedback" must work well on the Mini-Earth.
Simply put, "negative feedback" refers to a phenomenon or mechanism in which "the expansion of event A results in the contraction of event A (through various other phenomena)."
When a spring is stretched, it contracts due to elasticity, and when a pendulum swings to the right, a moment of force acts to swing it to the left.
In this way, most things that exist stably in the world have a negative feedback mechanism.
But, if you think about it carefully, the transparency of the water and the cleanliness of the walls may not be negative feedback, but positive feedback.
This is what happens when the expansion of event A causes A to expand even further.
The water becomes oligotrophic.
The growth of algae is suppressed.
Algae is eaten by snails and decreases in number.
The algae food supply of the small snails is insufficient, so the proportion of filter-feeding increases.
The clams, who have no other way to eat but filter-feed, have to obtain food from water with reduced plankton, so they take in and filter more water.
The filtering battle between the freshwater snails and clams removes more and more organic matter from the water, increasing transparency and further oligotrophy.
Moss is further suppressed!
What do you think?
This is exactly positive feedback, and I think that is the reason why, on Mini-Earth, once the water starts to become transparent, it becomes cleaner at an accelerated rate.
At this point, astute readers may be wondering, "Will aquatic plants be unable to grow in an environment where moss cannot grow?"
We can answer this as follows.
Algae that grows on walls is probably caused by too much sunlight, while general aquatic plants can grow with even less light.
Furthermore, by reducing the amount of algae on the wall and phytoplankton, the aquatic plants inside can receive more light.
A similar logic applies to oligotrophic water.
It is sufficient that the nutrient level is within a range where aquatic plants can grow but algae cannot.
In addition, aquatic plants that have deep roots in the soil are able to absorb nutrients from deep within the soil even if the water becomes oligotrophic.
In summary, the increased transparency of the water is proof that the Mini-Earth experiment is progressing in the right direction, and it seems unlikely that it will be easy to fall into a newly transparent environment!
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