1. Effects of Apostichopus japonicus consumption on dissolved oxygen

According to relevant data, at different temperatures, the oxygen consumption per unit time of Apostichopus japonicus is proportional to the size of the individual, the oxygen consumption per body wall weight is inversely proportional to the individual size, and the oxygen consumption is proportional to the logarithm of the body wall. There is a linear relationship between them, which is similar to the experimental results of fish and other invertebrates. In the normal range, the oxygen consumption of adult sea cucumber is about 0.4-0.8 mg/hour. Apostichopus japonicus relies on the breathing tree and the body surface to breathe at the same time. The respiration process is only one time of exhalation after inhaling water for countless times. At 19-22°C, water was exhaled every 9-15 times after absorbing water. When the water temperature was about 8°C, the sea cucumber showed only slight opening and closing of the anus, and it was difficult to distinguish whether it was absorbing water or exhaling water. In order to determine the proportion of skin respiration, the respiratory tree was removed. When the water temperature was 8.5 to 13.5 ℃, the proportion of skin respiration was 39% to 52%. When the water temperature rose to 18.5 ℃, the proportion increased sharply to 60% to 90%. , when the water temperature rises again, the proportion does not change much.

2. The effect of plankton on dissolved oxygen

Part of the dissolved oxygen in water comes from the air, and most of it is produced by plankton photosynthesis. Plankton produces oxygen during the day and consumes it at night, so the difference of dissolved oxygen in the water body during the day and night will be formed. In cloudy and rainy weather, plankton photosynthesis is weak, producing less oxygen, and Apostichopus japonicus is prone to hypoxia or death at night.

3. The influence of water temperature, salinity and weather on dissolved oxygen

In spring, the surface water temperature rises with the rise of atmospheric temperature, and there will be obvious water temperature stratification. Under the influence of wind in clear weather, waves will form on the water surface, which increases the contact area between water and air, and dissolved oxygen can be supersaturated at a depth of 0 to 1 meters. When the water level deepens or encounters cloudy and rainy days, especially heavy rains or rainstorms, a large amount of fresh water will be injected into the breeding pond to form a freshwater layer with low salinity. If it is not discharged in time, it will block the up and down transfer of dissolved oxygen . Especially at night, plankton moves downward and vertically to the bottom, coupled with the oxygen consumption of the sediment, the dissolved oxygen at the bottom of the pond continues to decline. This situation is more obvious in summer, and the lack of dissolved oxygen at the bottom of the pond will be further exacerbated. , so as to form a stable hypoxic layer, ammonia nitrogen and hydrogen sulfide gas harmful to the sea cucumber will be continuously produced, and it is easy to cause the sea cucumber to be hypoxic and suffocate to death.

4. Effects of Apostichopus japonicus excrement, bait and biological debris on dissolved oxygen

Apostichopus japonicus excrement, bait and biological debris accumulate at the bottom of the pool for a long time. These organic substances are eutrophicated and oxidized and decomposed at the bottom of the pool, which will quickly consume a large amount of dissolved oxygen in the water. The oxygen consumption of organic matter and the viscosity of water further lead to the inability of oxidative decomposition to proceed well. At this time, soluble ammonium salts and non-ionic ammonia (NH3) coexist in the water body in a certain proportion, but the proportion of the two varies with the water temperature. , pH value changes, among which ammonia (NH3) has strong toxicity to Apostichopus japonicus, it is easy to cause death of sea cucumber poisoning.