Aquatic Nitrogen Fixers for Fishless Aquaponics Systems. Nitrogen fixing is the way or a process where plants can take up nitrogen from the air and make it absorbable by roots. Plants cannot take nitrogen directly from the air. It first needs to be fixed. The chemical compound is NO3. Or called Nitrate. Nitrate is produced by a series of bacterium eating ammonium from fish waste, decaying organic material, or from bacteria eating proteins from legumes from nitrogen nodules.
There is another set of plants that fix nitrogen, but they function differently than legumes. They are called “nitrogen fixers”. Legume plants get a benefit from the invading bacteria by acquiring some proteins from the root-nodules. Plants use these proteins as building blocks. Fixed nitrogen is never created within the nodules. It is commonly thought the nitrogen fixing bacteria fixes nitrogen directly and saves it in the nodules. That is not the case. Rhizobium and Azotobacterae (nitrogen fixing plants) bacteria take starches from the plant through the roots and grow. When it comes time where the nodule goes anaerobic because of overpopulation, bacteria creates NO and then produces protean. The bacteria eats the proteins. In the case of legumes, some of the proteins are pumped back into the plant. In the case of Azotobacterae, nothing is given back to the plant, all is taken. When the plant dies, fungi and bacteria decompose the plants and release NH4, which is ammonia. Nitrosifyers and Nitrifying bacteria take over and produce fixed nitrogen. It is not until the plant dies, fixed nitrogen is released. That is why green manure works!
Dinoflagellate & Coral work together to fix nitrogen in water for plants. However, it lives mostly in salt water conditions. Cyanobacteria is one of the first bacterium to exist to fix nitrogen, but it needs at least three kinds of foods for it to grow; decay of organic material, bicarbonates in the water and light. If we want to reduce the number of fish in our tanks, it is possible to have the fish eat some of the Cyanobacteria (its close relative is Algae) as food and let the rest of the Cyanobacteria produce nitrates for the plants to use for growing material. However, we still need to have some sort decay to feed the Cyanobacteria.
I have not done this, yet! But I see it as a new avenue for cost reductions in vegetable productions for industrial Aquaponics systems. The problem I came across while trying to select the strain of Cyanobacteria is the agar recipe. It gets very involved. The recipe is not simple dextrose or other house hold things.
Since most, if not all, of the microbiology came from the ocean and waters, there is a nitrogen fixing symbiosis in water plants.
Cyanobacteria can make their own food from light. And also fixes nitrogen from the air for plants to absorb. Cyanobacteria have an important role in plant succession. They are considered the first nitrogen fixing plant; hence, called Primary Succession.
Cyanobacteria can be found in almost every conceivable environment, from oceans to fresh water to bare rock to soil. They can occur as planktonic cells or form phototrophic biofilms in fresh water and marine environments, they occur in damp soil, or even on temporarily moistened rocks in deserts. A few are endosymbionts in lichens, plants, various protists, or sponges and provide energy for the host. When nitrogen is consumed by fungi from cyanobacteria, it makes lichens.
Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas into ammonia (NH3), nitrites (NO2) or nitrates (NO3) which can be absorbed by plants and converted to protein and nucleic acids (atmospheric nitrogen is not bioavailable to plants).
Dinoflagellate & Coral
Another nitrogen fixer is a Dinoflagellate. Dinoflagellates are microorganisms located in either fresh or salt water. They are the unicellular structures that are often referred to as algae. Their exact locations depend mainly on the temperature and depth of the water. A single characteristic which is the main reason for their classification is the flagellum that comes off of the inner part of their body. They are the main producers of the water, as they are small organisms that perform photosynthesis. Some of these can even be parasitic.
When conditions in the dinoflagellates life become unstable, they have to change themselves dramatically. At this point, two of these organisms will form together, creating a “planozygote.” Then it goes through another stage, which is much like that of hibernation, called hypnozygote. During this stage, the microorganism will take in fat and oils to change its shape and allow its case to become harder. When the circumstances in the weather change, the dinoflagellate will break out of the shell and take on its familiar form with the dinokaryote nucleus.
There are two types of dinoflagellates known – heterotrophic and autotrophic. The heterotrophic organism eats and depends upon other types of organisms whereas autotrophs produce their own food by a process called photosynthesis, though some may be a combination of the two.
These microorganisms can sometimes produce neurotoxins during red tide. These toxins will ultimately kill fish or infect those which humans eat, thereby passing the disease to the human. The red tide can increase with human input of salts and phosphate acid. When humans consume fish with these neurotoxins, it can be fatal. Medical and economic studies are being made on this particular subject in order to decrease the happenings of these red tides.
However, not all types of these miraculous reproductive tides are harmful. At night, blue flashes may be seen in the ocean. This is because of the dinoflagellates ability to produce their own light. Much like the firefly, they contain the a substance bioluminescence which allows them seemingly to glow. These lights occur mainly when the dinoflagellate is disrupted.
Some Dinoflagellates are parasitic and they can live with a host. When it comes to using these animals with Aquaponics, it is important to get freshwater varieties. Salt water varieties will not work the ”soil” plants because the salt will prevent nutrient movement into the roots.
Below is a picture of a microbialites. This is one of very few freshwater corals that Dinoflagellates may connect with to grow. Since this freshwater coral is rare and hard to find, it are not be a good candidate for Aquaponics. The majority of symbiotic relations between Dinoflagellates and coral are located in salt water.
Microbialites are rock structures that are created, in part, by the bacteria that live on their surfaces. They were the only forms of life on Earth for the first few billion years of its history. Microbialites are rare on Earth today, and exist only in extreme environments. There are several hypotheses about how the microbialites at Pavilion Lake formed, and a major focus of the Pavilion Lake Research Project is to conduct experiments to understand how these structures grow.