A Brief Introduction to Microbes in Aquaponics

Posted by Amy Storey on December 2, 2014

A Brief Introduction to Microbes in Aquaponics

The world of microbes is so extensive and diverse that it’s been estimated we have identified less than 1% of microbial species. Our understanding of the microbial life in aquaponic systems is infinitesimal. Dr. Storey said,
“When you figure that a shovel-full of dirt contains a hundred times as many bacteria as we know about… well, we know about as much about microbes as we do the other side of the galaxy! I’m convinced that there are all sorts of other amazing things happening in these systems that we just have no idea of, because they're all done by microbes that we can’t culture, that we have a hard time surveying, understanding.”
Of bacteria alone there are estimated to exist 1030 species... wow!
 
There is very little that we really know about microbes, although we can observe the results of their collective presence in our aquaponic systems.

Why are Microbes Important?

To see the importance of microbes in an aquaponic system, let's imagine what would happen without them. Of course, a system void of microbes (heck, an organism void of microbes) is an impossibility. Microbes are everywhere, and will find their way into your system.
 
They will enter the system via the air, the water you use, the seeds you plant and the soil you plant them in, in the guts and on the scales of fish... etc., etc. There's no way to avoid them. Because they're such an integral part of life, we often forget about them and take them for granted.
 
But what if they weren't in your system? What would happen?
 

Hypothetical Absence of Microbes = Ammonia Accumulation

Perhaps the most obvious result of no microbes would be fish death from ammonia accumulation.

Here's how it works: As fish metabolize and perform their basic physical functions, they are producing ammonia. In fact, most animals produce ammonia at some point during their physical processes. Mammals (like us) convert ammonia to urea and get rid of it in urine, but fish don't. Instead it passively seeps through their cells through a diffusion gradient.

 

diffusion gradient 2 Molecules of ammonia move from a region of higher concentration to a region of lower concentration.

This means that ammonia molecules travel from an area of higher concentration (inside the fish) to an area of lower concentration (outside the fish, in the water). Without the microbes there to break it down, almost all of the ammonia from the fish sticks around, until finally, there is as much ammonia outside the fish as there is inside the fish.

At this point, the diffusion gradient (high concentration to low concentration) no longer exists. The ammonia inside the fish will not diffuse out because the concentrations inside and outside are the same. Without the different concentrations, the fish dies, poisoned by its own ammonia.

 

Hypothetical Absence of Microbes = Widespread Deficiencies

Another thing that would happen is that your plants would be deficient in almost everything.
http://www.extension.uidaho.edu/nutrient/images/Wheat/WheatSdef1.jpg
 
For almost every nutrient there is a transition that happens (a biological mediation) that takes the nutrient from being an organic solid to being something that the plants can absorb.
 
For example, in fish feed there is a lot of phosphate, but that phosphate is not available to the plant as it exists in the feed- a microbe takes it and breaks it down, changing it into something usable. We rely on microbes to make nutrients available to plants. And that goes for almost any system in the world.
"Without microbes, we die. Everything dies. We tend to think of fish as being fish, and plants as being plants, and microbes as being microbes. But we should be thinking about fish and microbes being fish, plants and microbes being plants."

We need microbes to be a part of our systems as much as we need fish and plants and water. But do they need us?

We can assume that much more happens to the microbial populations in an aquaponic system than we understand, so it's hard to speculate whether or not our actions affect them significantly. What we can do is observe the results of our actions. Dr. Storey and the Bright Agrotech team have had a lot of time to do just that.

One environmental factor that continually comes up in conversations about microbes is pH. In our next post, we'll examine the role of pH in the world of microbes.

More on Microbes: Aquaponics Academy Episode #7

Find more podcast episodes here.

 

 

Topics: Aquaponics

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