In shrimp culture, aeration plays significant role for solving the problems occur in higher stocking rates. Aeration not only acts to increase the oxygen concentration for culture ponds but also resulting in better FCR and improved health. However, no study has hither to been conducted to evaluate the optimum amount of power utilization (hp) for aeration for production (kg) of pacific white shrimp, Litopenaeus vannamei, in semi intensive system. Therefore, a study is proposed to quantify the power (hp) consumption of aspirator model aerator for shrimp production (kg) in high density stocking conditions. The study will be conducted in polythen liner ponds (1000m2) at the KAU Fish Farm, Faculty of Marine Sciences for a period of 4 months. Aspirator injector model aerator (Force-7, Aqua &Co, Italy) will be used for testing the power utilization for maintaining dissolved oxygen level in pond water. There will be control and treatment for the study. In control ponds, aerators will be operated to maintain dissolved oxygen (DO) between 4-6ppm (standard DO level); whereas in treatment ponds DO will be maintained between 3-4ppm (minimum DO level) throughout the culture days. Shrimp juveniles of uniform size (1g) will be stocked at the rate of 100pcs/m2 in each pond and a standard shrimp feed (NAQUA, Jeddah) having 35% protein will be supplemented as feed. Physical and chemical water quality parameters such as temperature, dissolved oxygen, salinity, pH, ammonia, alkalinity, nitrate and nitrites will be recorded during culture days. Weekly sampling will be done to record average body weight (ABW) and survival of shrimp. Once shrimp attains marketable size (20g), harvest will be done and the total power consumption (hp)/production (kg)/pond will be estimated. The data obtained from the study will be subjected for statistical analysis to compare the difference in growth, survival and biomass production between control and treatments. It is expected that the outcome of this research would have great significance in the field of commercial aquaculture industry in the Kingdom.
In shrimp culture operations, aerators play significant role to maintain dissolved oxygen (DO) level for high growth and production (Boyd, 1998; Nunes and Musig, 2001). DO is the most critical element of water quality because all aerobic aquatic organisms need a constant supply of oxygen to survive (Boyd and Watten, 1989). Consequently, a basic understanding of the mechanisms of oxygen production, transfer, and depletion is necessary to support aquaculturists in the successful pond management (Tucker, 2005). Pond aerator not only acts to increase the oxygen concentration in culture ponds but also resulting in better FCR and improved health (Boyd, 1997; 1998). The low levels of dissolved oxygen in pond water may led poor feed consumption, digestion, growth rate and enhances the chance to infectious diseases (Lawson and Wheaton 1983; Boyd, 1998; Boby Ignatius, 2001; Santa and Vinatea, 2007).
Aerators work by increasing the area of contact between air and water. Aerators also circulate water so shrimp can find areas with higher oxygen concentrations. Movement of water reduces stratification of water layers and increases oxygen transfer efficiency. Aeration involves transferring gaseous oxygen from the large reservoir in the atmosphere into the waters of the pond where DO concentrations have dropped to critical levels (Boyd and Watten, 1989). Depending on how low the dissolved oxygen concentration is and how long it remains low, shrimp may consume less feed, grow more slowly, convert feed less efficiently, be more susceptible to infectious diseases, or suffocate and die (Tucker, 2005). These problems can be avoided by aerating ponds mechanically with suitable aerators (Boyd, 1998).
Since dissolved oxygen plays significant role in aquatic life, the amount of oxygen in water is vital for all aquatic organisms living in the water and having an aerobic type of respiration (Santa and Vinatea, 2007). Therefore, the main role of aeration is to enhance the oxygen concentration in water. In shrimp culture, especially in intensive or semi intensive system, this is more critical because, when dissolved oxygen level tend to go below than 2ppm, it may lead mass mortality in culture ponds (Lawson and Wheaton 1983). Dissolved oxygen is a crucial parameter, which has incredible effect on growth and production of shrimp through its direct effect on feed consumption and metabolism. Absence of dissolved oxygen may cause a substantial increase in the level of toxic metabolites in culture ponds. Hence it is important to maintain dissolved oxygen at optimum levels of above 3.5 ppm throughout the culture period. (Boby Ignatius, 2001). According to Boyd (1988) aeration is important for shrimp production and for an average production of 500kg/ha requires 1KW or 1.34Hp. Since the devices used for aeration consume more power and increases cost of production, a study is essential to optimize the use of aerators for the production shrimp and to assess the power requireme