Freshwater nucleated pearl culture management techniques and is it more expensive than seawater pearls?

1 Selection of pearl culture water body
  The pearl culture water body should be at least 2000 sq m, with slight water flow, and a water depth of more than 2 m. If the water is too shallow, the pearl mussels are easily affected by toxic substances such as hydrogen sulfide, ammonia and methane from the bottom layer. During the peak growth period of pearls from May to October, it is best to create slow-flow conditions.

When selecting a pearl culture water body, a physicochemical and biological survey of the bottom mud must be carried out. If the bottom mud contains various anaerobic bacteria, then in the high-temperature season a large amount of toxic substances such as hydrogen sulfide, methane, amines and methyl indole will be produced. Before pearl culture production, quicklime must be spread on the bottom mud for improvement treatment.
  2 Pearl culture density in the aquaculture water body
  To determine the culture density of pearl mussels, the biomass of palatable food organisms in the aquaculture water area should be measured. Through research on the culture and reproduction characteristics of palatable algae and Chlamydomonas (Lobomonas sp.), the algal production potential of the pearl culture water body can be predicted, and the optimal pearl culture density determined.
  3 Determination of the optimal pearl culture water layer
  The physicochemical and biological properties of each water layer in a pearl culture water body differ, so pearl mussels must be suspended and cultured in the optimal pearl culture water layer. Based on the relationship between algal biomass and transparency, the relational formula for the optimal pearl culture water layer in a pearl culture water body can be obtained: optimal pearl culture water layer (cm) = transparency (cm) x 0.8.
  If the culture water layer for pearl mussels is too shallow, heat coma is likely to occur in the high-temperature season. This is because in the high-temperature season the shallow water layer has the greatest distribution of blue-green algae, and their toxins affect the growth of pearl mussels. Of course, the culture water layer should not be too deep either, otherwise the biomass of food organisms will be insufficient.

  4 Supplementing nutrient elements in the pearl culture water body
  (1) Rare earth elements
  The content of rare earth elements in pearl culture water areas is generally very low, because in nature rare earths mostly exist as components of mineral crystal lattices or in adsorbed states between mineral particles. Therefore, the soluble rare earths that can be directly absorbed and utilized by pearl mussels in the water body often cannot meet the normal needs of pearl mussels. Thus, applying a small amount of soluble full-element rare earths in pearl culture water areas can show obvious effects.
  Although rare earth elements are not nutrient elements needed in large amounts by shellfish, nor are they inherent constituent elements of pearls and shells, in the physiological and biochemical processes of nacre secretion and deposition, rare earth elements can play an "activator" role. When the pearl culture water environment lacks certain elements necessary for nacre deposition, such as Ca, Mg, Zn, Se, etc., certain elements in rare earths can play a substitute role.
  At the same time, among rare earth elements there are light-producing elements and color-producing elements for pearls, which play an important role in improving quality traits such as pearl luster, refractive index and color saturation.
  The author's research test results show that the promoting effect of rare earths on nacre secretion in Hyriopsis cumingii is: mixed rare earths > light rare earths > heavy rare earths. Their suitable concentrations for promoting nacre secretion are respectively: mixed rare earths 100 g/m3, light rare earths 100-300 g/m3, heavy rare earths 100-150 g/m3.
  Bottom soil under water areas developed from different soil parent materials has different physicochemical properties, and the rare earth background values in the water body also differ. The rare earth content in the water body increases with the increase in bottom soil viscosity. In bottom soil water areas developed from granite parent material, the rare earth content in the water body is relatively high, so the concentration used should be reduced; in bottom soil water areas with heavy sandiness, the rare earth content in the water body is generally relatively low, so the concentration used should be increased.
  (2) Introduction of photosynthetic bacteria
  Among photosynthetic bacteria (abbreviated as PSB), those suitable for pearl mussels include green sulfur bacteria, red sulfur bacteria and red non-sulfur bacteria. Their bacterial cells not only have extremely high protein content (crude protein about 58%), but their amino acid composition is also not inferior to yeast, soybean and egg white, making them an excellent-quality palatable food organism for pearl mussels. At the same time, PSB can effectively improve the main ecological factors of pearl culture water areas (pH, DO, COD, ammonia nitrogen, etc.), and in particular has the unique function of eliminating H2S and other substances produced by anaerobic decomposition of bottom mud under oxygen-deficient conditions, which are highly toxic to pearl mussels.
  C02+2H2S→[CH2O]+H20+2S2
  After photosynthetic bacteria are introduced into pearl culture water areas, whether anaerobic and bright, or aerobic and dark, they can reproduce very well. Therefore, in competition, PSB populations often occupy an advantageous and superior position. Under anaerobic and bright conditions, they use light energy to fix carbonate and reproduce by using hydrogen or organic matter as hydrogen donors, and can also use low-grade fatty acids and other organic matter as carbon sources.

Are freshwater nucleated pearls expensive? Generally, market prices of more than 100 yuan, more than 200 yuan, more than 300 yuan, more than 400 yuan or a bit higher are all possible. Are freshwater pearls expensive or seawater pearls expensive? Seawater ones are more expensive than freshwater ones.