DIYAS development Limited , https://www.diyastea.com
In the northern regions, most sea cucumber farming is conducted in open-air tidal zones and reef ponds. Many farmers believe that during winter, low temperatures reduce the need for management, leading to significant losses of sea cucumbers due to neglect. Over recent years, it has been observed that large-scale disease outbreaks in farmed sea cucumbers occur at similar times. In Shandong, this period typically spans from mid-February to early May, with the peak occurring between March and April.
During this time, a key factor influencing the environment is the gradual recovery of both air and water temperatures after the cold winter. However, the rate of temperature increase differs between air and water—air warms quickly while water warms more slowly, creating a lag effect. When the air temperature exceeds the water temperature, a temperature stratification occurs in the pond, with warmer, less dense water remaining on top and preventing mixing with the colder, denser water below. Measurements show a temperature difference of 1 to 2 degrees between depths of 1 meter and 3 meters.
This stratification leads to poor water circulation, trapping the lower layer of water, which becomes "dead water" with insufficient dissolved oxygen. The upper layer remains well-oxygenated, but the lack of convection prevents oxygen from reaching the bottom. At the same time, sea cucumbers consume oxygen through their metabolic activities and the breakdown of organic matter. Without sufficient oxygen supply, the bottom layers become hypoxic or even anoxic. Testing shows that dissolved oxygen levels in the bottom water often fall below 3 mg/l during this period.
Under these conditions, sea cucumbers experience reduced metabolic activity, and their circulatory, nervous, digestive, and respiratory systems are impaired. Their ability to resist stress and disease decreases significantly. Additionally, anaerobic bacteria thrive in low-oxygen environments, breaking down organic matter and producing harmful substances like ammonia nitrogen and hydrogen sulfide, which further harm the sea cucumbers. As water quality deteriorates, the sea cucumbers become weaker, making them more susceptible to bacterial infections and other pathogens.
To prevent these issues, it's crucial to maximize water exchange in the ponds, especially when high tides occur, to bring in fresh water. Farmers should also aim to minimize daily temperature fluctuations and extend the period of water flow as temperatures rise. Regular monitoring of the ponds is essential, and divers may be sent to check the activity of sea cucumbers at the bottom. If any affected individuals are found, they should be removed immediately and soaked in disinfectant to prevent the spread of infection to healthy ones. Proactive management can significantly reduce losses and improve the overall success of sea cucumber farming.