Treatment of blue algae in white shrimp

In the process of shrimp farming, people are more afraid of blue algae. Once blue algae appear, it will often cause shrimp to become sick or even die in large numbers. Therefore, it is necessary to prevent blue algae in time. Some measures can be taken to avoid the death of shrimp due to blue algae and cause economic losses. For example, scientific feeding is needed, and prevention should be strengthened by using bacteria to promote algae and other methods.

1. The harm of cyanobacteria: When cyanobacteria explode in high-level ponds, Microcystis and Oscillatoria often form a layer of emerald green algae on the water surface. This phenomenon is called "algae bloom" by farmers. Not only can the white shrimp not eat blue algae, it also hinders the diffusion of oxygen in the air into the water. At night, it consumes a large amount of dissolved oxygen in the water, which can easily cause the white shrimp to die from stress, poisoning, and lack of oxygen. When the density reaches 500,000 colonies/liter, a large number of them will die. The algal toxins, toxic hydroxylamine, hydrogen sulfide, etc. produced by the decomposition of the corpses will harm the white shrimp. In addition, Cai Zengshan, a senior engineer at Hubei Jingzhou Fisheries Research Institute, believes that early mortality syndrome (EMS) of shrimp is the main reason for the low success rate of shrimp farming. Early mortality syndrome of shrimp is often accompanied by an outbreak of cyanobacteria, which is one of the causes of early mortality syndrome of shrimp. 2. Causes of blue algae production

(1) Climate influence: When the water temperature is between 28-30℃, blue algae grows fastest. When it exceeds 25℃, it will grow significantly faster than other algae. This is why blue algae often erupt in spring and autumn. In addition, the area of ​​the high-level pool is small, and the breeze is conducive to the aggregation of algae. The strong light is also conducive to the photosynthesis of algae, accelerating the division and growth of cyanobacteria.

(II) Unreasonable stocking density of seedlings. The culture of whiteleg shrimp in high-level ponds is a high-density intensive culture model. The culture density is too large, exceeding the carrying capacity of the water body. At the same time, the residual bait produced by long-term and large-scale feeding contains a large amount of phosphorus. The large amount of excrement of whiteleg shrimp and the accumulation of corpses of dead planktonic microorganisms provide rich nutrients for the massive reproduction of cyanobacteria. After a period of time, cyanobacteria inhibit the growth of beneficial algae.

(III) Improper Management: The majority of farmers have low levels of training and education, and the technology they use is based on old experience. They mistake algae blooms for good water quality and color, which leads to a lack of scientificity in the breeding process, missed optimal treatment opportunities, and increased EMS incidence.