The amount of oxygen dissolved in the pond water is vital to the shrimp's health. However, in the culture pond, dissolved oxygen is mainly consumed by pond sediment (50-70%) and plankton (20-45%). Only a small portion of dissolved oxygen is consumed by the shrimp (5%).
Adequate level of Dissolved Oxygen (DO) can be ensured in water column by 3 methods.
- By installing different types of Aerators,
- y controlling plankton density to an optimum level,
- By minimizing the unwanted organic substances which consume oxygen, such as uneaten feed waste, fecal matter, dead benthic algae, black soil etc.
Aerators:
Aerators play a critical role in Pond Oxygenation in Semi-intensive and Intensive culture systems.They primarily maintain adequate oxygen levels and facilitate gaseous exchange. Use of aerators also mix the pond water column well to prevent stratification. The suspended wastes as dead algae,fecal matter,silt also settle in the center of the pond due to water currents.
Key Points to remember :
- Decide and fix sufficient aerators @ min 1 HP / 400 kg biomass,
- Properly position the aerators to achieve maximum flow with minimum energy,
- Check DO levels of Pond water 4 times a day as Early morning, Afternoon, Evening and Late night,
- Always ensure minimum Dissolved Oxygen to be above 4ppm,
- Water exchange is the last option to adjust Dissolved Oxygen,
- Stop aeration during feeding and Chain dragging,
- Use aerators during Liming and Fermented Juice application for even distribution
Factors / Incidents affecting Dissolved Oxygen:
- High phytoplankton bloom increases Oxygen demand.
- Cloudy weather results in less photosynthesis.
- Sudden Bloom crash results in less photosynthesis.
- Usage of Disinfectant, Algicides kills Algae and increases Oxygen demand inside the pond.
- Bad Bottom soil increases the Oxygen demand.
- High DOC with insufficient aerators/power failure increases Oxygen demand.
- High Temperature increases Oxygen demand.
- High Salinity increases Oxygen demand.
- Deeper the Pond, lesser with be the Oxygen levels.
