Water Monitoring is a big task in shrimp farming. If the water isn’t just right, it can stress out the shrimp and mess up their growth and survival.
So, it’s super important to make sure the water quality is good for shrimp to grow healthy and strong. Monitoring water parameters like the pH, oxygen levels, and minerals is a key. When we watch the water closely, we can fix any problems fast and keep our shrimp happy and growing well.
The Optimal Dissolved Oxygen Levels for Shrimp Farming
Monitoring Dissolved Oxygen (DO) levels holds critical importance for all aquatic life forms. DO levels serve as an indicator of the suitability of an environment for sustaining aquatic life. The quantity of dissolved oxygen depends on water temperature, salinity, various decomposition processes within the water, and the photosynthesis activity of plankton.
Photosynthesis by plankton mainly occurs during daylight hours, resulting in higher dissolved oxygen levels during this period. Conversely, during nighttime hours, aquatic organisms and plants continue to consume oxygen for respiration and produce carbon dioxide. Consequently, DO levels decrease during the night. Given the indispensable role of oxygen in the respiration of aquatic life, particularly in the context of aquaculture, maintaining adequate DO levels is of the utmost importance.
In shrimp ponds, it is essential to ensure that there is at least 5 ppm of dissolved oxygen because that’s what shrimp prefer. If there isn’t enough oxygen, it can disrupt their feeding, the breakdown of substances in the pond, and even their molting. This can slow down shrimp growth and lead to issues in shrimp farming. So, keeping oxygen levels above 5 ppm helps keep shrimp happy and makes shrimp farming more productive.
The optimal pH levels for Shrimp Farming
pH, or the potential of hydrogen, plays a pivotal role in shrimp aquaculture. It is a monitoring of the acidity or alkalinity of water, indicating the concentration of hydrogen ions present. The pH scale ranges from 1 to 14, with 7 being considered neutral. Values below 7 signify acidity, while values above 7 is alkalinity.
It is noteworthy that pH levels in water undergo fluctuations throughout the day due to photosynthesis by aquatic plants. During daylight hours, the photosynthesis process reduces the concentration of carbon dioxide (CO2) in the water, resulting in an increase in pH (alkalinity). Conversely, at night, aquatic organisms respire and release carbon dioxide, causing water to become more acidic, leading to a decrease in pH.
In shrimp farming, maintaining an optimal pH range of 7.0 to 8.5 is critical. Excessive or frequent fluctuations in pH can induce stress in shrimp, reduce their growth, and compromise their immune systems, leading them to face diseases.
Furthermore, pH levels affect the toxicity of ammonia and hydrogen sulfide in the water. A decrease in pH can elevate the toxicity of hydrogen sulfide, while an increase in pH can heighten the toxicity of ammonia, both of which can adversely impact shrimp health and survival.
The optimal Alkalinity levels for Shrimp Farming
The alkalinity level of water plays a role in controlling changes in pH levels, ensuring that it remains within an acceptable range (buffering capacity). Alkalinity is directly related to the presence of magnesium ions in water, which stabilizes pH levels, minimizing fluctuations. This stability is essential to maintain shrimp in a balanced state, enabling them to efficiently utilize mineral elements for survival and growth.
The suitable alkalinity range for shrimp farming is typically between 80-170 mg/L. Within this range ensuring complete and healthy molting. If alkalinity levels fall below 80 mg/L, it can result in incomplete molting and soft shells. This can be corrected by adding Dolomite lime or Sodium Bicarbonate at 150 kg per hectare during period.
Conversely, The alkalinity levels exceeding 170 mg/L can might hinder shrimp molting, leading to hard body. In such cases, we have to reduce alkalinity by exchanging water or adding 90 liters of molasses per hectare every 5-7 days, gradually lowering the alkalinity level. During this adjustment period, it’s important not to add lime to the water.
How changes in Water Temperature affect Shrimp Farming
Monitoring changes in water temperature is crucial in shrimp farming because shrimp are cold-blooded animals. These temperature shifts directly affect aquatic life, including shrimp. Specifically, when water temperature increases by 1 degree Celsius, the metabolic processes of aquatic creatures, including shrimp, become ten times more active. Consequently, higher temperatures lead to an increased demand for food and oxygen among these organisms.
Furthermore, temperature fluctuations also impact the decomposition of organic matter by microorganisms, resulting in a reduction in the dissolved oxygen levels within the water. Therefore, it’s essential to monitor water temperature closely. The ideal temperature range for promoting the growth and development of shrimp typically falls within the range of 28-30 degrees Celsius.
The impact of RainFall on Water Quality in Shrimp Farming
Rainfall during the rainy season can have significant effects on the water quality in shrimp ponds. The amount of rainwater that enters the pond can cause a drop in water temperature of around 3-5°C. Rapid temperature changes can lead to shock and stress in shrimp, making them appear lethargic and less active. Prolonged, heavy rainfall with low acidity or alkalinity levels can gradually reduce the water’s pH to as low as 6.7. This drop in pH prevents shrimp from molting properly. Additionally, the decreased alkalinity stimulates the growth of vannamei shrimp, reducing the salinity of the water in the pond due to dilution by rainwater.
Normally, shrimp strive to maintain a balance of essential minerals in their bloodstream. When vital minerals in the water decrease, shrimp need to expend more energy to absorb these minerals into their bodies. This can lead to weakened shrimp that are more susceptible to illness or death after molting.
Water hardness is also affected by rainfall and depends on the amount of rain. Rainfall reduces the intensity of light entering the pond, hindering photosynthesis in the pond’s phytoplankton. As a result, the majority of phytoplankton die, causing the water to become turbid. Sometimes, shrimp may exhibit darker gills due to debris or phytoplankton remains getting trapped in their gills. Weaker shrimp may start clinging to the pond’s edges. The death of phytoplankton is another reason for the decrease in dissolved oxygen (DO) levels in the pond. If DO levels drop below 3.0 ppm, shrimp become weaker, eat less, and are at risk of molting complications that may lead to death.
Water Monitoring during rainfalls
Before the rainy season arrives, shrimp farmers should assess the forecasted rainfall for the year, whether it’s expected to be heavy or light. During continuous heavy rain, it’s crucial to increase aeration or turn on aerators. This is because, during such times, phytoplankton in the pond struggle to effectively carry out photosynthesis, which can result in lower oxygen levels.
Furthermore, it’s important to add lime to maintain a stable pH in the water since heavy rain often lowers the pH. Ensuring a regular supply of essential minerals, especially during molting periods, is also necessary to help shrimp quickly regenerate their shells and maintain good health. This proactive approach ensures a successful shrimp farming season even in the face of heavy rainfall, as forecasted.