Ammonia and Nitrite formation in shrimp pond. Why salts used to reduce nitrite toxicity in low saline water?

Hello everyone:

 Today we will see about ammonia and nitrite formation in shrimp pond and will see the reason why salts added to reduce nitrite in shrimp pond.

Before that ... We must know about osmoregulation.

Yes, Osmoregulation is a physiological process that occurs in aquatic organism to maintain the fluid in equilibrium. It said as salt and water balance of an organism. It happens in every aquatic organism.

 Freshwater fish - high salt in body than the surrounding medium.

 Marinewater fish - low salt in the body than the environment.

Usually the osmosis is the movement of water from low to high concentrated solution. kidney and gills do osmoregulation process.Through the skin and gills the exchange of water and salt takes place.

In Marine fishes have low concentration of salt in body compared to the environment. You imagine the Marine fish lives in the water with high salt content. The water present in the fish body moves into the environment through skin. This process is osmosis.( because water moves from low to high concentration). 

If this process happens means there is a problem of  loss of water in Marine fish occurs. To prevent this problem Marine fish drinks excess amount of water compared to freshwater and also it's excreted concentrated urine. Because if the urine is diluted means there is water loss occurs. So the modification of glomeruli in kidney of Marine fish retains the water inside of the body.

(Diffusion- movement of chemicals from high to low concentration.)

 I hope you understand about osmoregulation😊.

We will move into main topic. Pls continue the reading.......

Ammonia is present in two forms in water unionized ammonia and ionized form(Ammonium).

In this, unionized ammonia is very toxic and leads to change in water quality.

Ammonia is excreted as a metabolic waste of protein in shrimp body. vannamei is cultured in different salinity of water.

But there is many problems will be faced during low saline culture because of absence of much minerals in water.

High saline water prevents the solubility of toxic gases in water compared to freshwater.

High saline water maintains proper osmoregulatory function of the animal.

Ammonia is mainly excreted through gills and excreted through fecal matter by the shrimp that is present in the pond. We know that, shrimp requires high protein feed in the diet. 100 gm protein contains 16 gm of nitrogen. So there is a high chance for ammonia accumulation in pond. It also forms by wastage of feed and decomposition of any other solid particles like leaf ... It also leads to chance for producing ammonia in water. Ammonia has the capability of diffusing in the animal body by the process of diffusion.

Dead planktons settled on the bottom of the water. It also leads production of ammonia.

Ammonia - Nitrite - Nitrate ( nitrification process).

This process is accompanied by nitrifying bacterias that present in the pond bottom.

If any imbalance between these bacterias , it will affects the entire process.

Unionized ammonia is highly toxic in low DO condition. In low DO condition there is lot of possibilities of occuring denitrification process. So DO must be maintained in the constant level in water.

Nitrate - nitrite - nitrous oxides - nitrogen gas ( denitrification).

 Nitrite is the intermediate product of the both process. If nitrite toxicity increases, it enters into the blood and affects the oxygen binding capacity of the shrimp. Haemocyanin is present in shrimp. If nitrite enters into blood stream it reacts with haemocyanin and form methaemocyanin and causes hypoxic condition in body tissue.

It will affects the gills of the shrimp and reduce metabolism and leads to death of the shrimps.

After sudden increase in ammonia there is sudden increase in nitrite occurs.

In general, Ammonia causes reducing the osmoregulatory function of the Shrimp.

It causes stress condition to the shrimps.

Ammonia increases means automatically nitrite also increases. In this we prevents the nitrite toxicity by applying salts or giving proper nitrifying bacterias.

If we give salts, there is increases in chloride content of the salt increases salinity and reduce the solubility of toxic gases in pond. In stressed Condition, shrimp excreted excess of ammonical matter in the pond. If we applied salt into the pond, it regularise the osmosis and decrease the excretion of ammonical waste from the shrimp.

Increased chloride ion decreases nitrite toxicity. It also reduces the excretion of Ammonia from gill.

Salinity have the inverse relationship with nitrite toxicity.

Salinity increase -- nitrite toxicity decreases.

This is the main function of salt in the prevention of nitrite toxicity in the pond water. High pH, high temperature increases the toxic nature of ammonia. If Ammonia accumulated in the pond, it affect entire body of the Shrimp. Reduced feed consumption, sudden moulting, poor growth, affects the immune system of the Shrimp and nitrite toxicity affects the gills of the Shrimp.

If we maintain the proper feed in the pond system, we can reduce the Ammonia formation in the pond. Proper removal of bottom sludge, proper pond preparation and maintenance of proper bacterial colonies in the pond system can leads to good culture.....😊🦐