Method for improving survival rate of water chestnut shell seedlings

Abstract

The invention discloses a method for improving the survival rate of water chestnut shell seedlings. The method comprises the following steps: placing a plastic film or a corrugated plate in a water tank, adding an algae nutrient solution, suspending flowing water, carrying out aerated culture for 15-30 days, installing a black sunshade net above the water tank, enabling the illumination intensity to be lower than 5000 Lux, the temperature of a culture water body to be 20-30 DEG C and the salinity to be 30-32 ppt, after the benthic diatom is overgrown, draining all water in the water tank, opening the sunshade net, and exposing the benthic diatom under sunlight, and when a part of benthic diatom dies, adding water into the pool for ventilation, arranging a sunshade net again, then transferring the horseshoe snail fertilized eggs into the diatom pool after solarization, pausing flowing water, and performing ventilation culture. According to the method, about 30%-70% of benthic diatom is dried to death by using a sunlight exposure method, and meanwhile, part of fresh benthic diatom is reserved, so that the attachment metamorphosis and survival of the horseshoe snail larvae are remarkably improved, and a technical support is provided for large-scale production of the horseshoe snails.

Description

Technical Field

[0001] The invention belongs to the technical field of marine animal cultivation, and in particular relates to a method for improving the survival of horse snail seedlings. Background Art

[0002] The horseshoe snail belongs to the phylum Mollusca, class Gastropoda, subclass Prosobranchia, order Protogastropoda, family Horseshoe Snail, genus Horseshoe Snail. It often lives in the middle and upper layers of the intertidal zone and the subtidal zone, and mainly feeds on algae attached to rocks by scraping with its tongue. As the main marine economic shellfish in the South China Sea, it has unique ornamental and medicinal value. At the same time, it is also an important herbivorous gastropod in the coral reef ecosystem of the South China Sea, and it is also a key species in many island reef ecosystems. Its grazing effect on large benthic algae can effectively control the biomass of algae in the coral reef ecosystem, ensuring that corals are in a dominant position in the competition for ecological niches, thereby maintaining the balance of interspecific relationships within the coral reef ecosystem (Li Yinghong et al., 2014; Villanueva et al., 2013). However, due to climate warming and the intensification of human activities, their survival, metabolism, reproduction, development and other life activities have been affected to varying degrees, resulting in a significant reduction in the wild resources of horseshoe snails (Zhang Tianyu et al., 2020). Therefore, the development of artificial breeding technology for horseshoe snails is of great significance to meeting market demand and maintaining the stability of the South China Sea coral reef ecosystem.

[0003] At present, my country has mainly carried out a series of research on artificial induction of production, artificial seedling cultivation, artificial breeding and offshore intermediate cultivation technology for giant horseshoe snails and tower-shaped horseshoe snails. Among them, in the process of artificial seedling cultivation, the settlement and metamorphosis of horseshoe snail larvae is the key to the success of seedling cultivation, and it is also an important step in determining whether large-scale seedling cultivation can be carried out. However, the attachment and metamorphosis rate of seedlings in the currently reported seedling cultivation methods is not high, which to a certain extent limits its industrial production. Therefore, it is very necessary to explore a method to improve the attachment and metamorphosis of horseshoe snail larvae for its large-scale application. Based on this demand, through many attempts, we have developed a method that can significantly improve the attachment and metamorphosis of horseshoe snail larvae, providing technical support for the industrial development of horseshoe snails. Summary of the invention

[0004] The purpose of the invention is to provide a method capable of significantly improving the survival rate of horse snail seedlings, and solve the problem of low seedling raising rate in the process of artificial seedling raising.

[0005] The method for improving the survival of horse shoe snail seedlings of the present invention comprises the cultivation of benthic diatoms, the exposure of benthic diatoms and the attachment and metamorphosis of larvae. The method is characterized in that: a plastic film or a corrugated plate is placed in a water pool, an algae nutrient solution is added, the water flow is stopped, and aeration culture is carried out for 15-30 days. A black sunshade net is installed above the water pool so that the light intensity is lower than 5000 Lux, the temperature of the culture water body is 20-30 DEG C, and the salinity is 30-32ppt. After the benthic diatoms are fully grown, all the water in the water pool is drained, the sunshade net is opened, and the benthic diatoms are exposed to the sun. When some benthic diatoms die from the sun, water is added to the water pool for ventilation, the sunshade net is laid again, and then the fertilized horse shoe snail eggs are moved into the diatom pool after the exposure, the water flow is stopped, the aeration culture is carried out, and after all the floating larvae in the water body are settled, the ventilation volume is increased and the water flow culture is carried out. During this period, if it is found that the amount of benthic diatoms is insufficient, fresh benthic diatoms are added in time.

[0006] Preferably, the algae nutrient solution ratio is preferably: add 0.3g sodium nitrate, 0.3g urea, 0.05g potassium dihydrogen phosphate, 0.005g ferric citrate, and 0.05g sodium silicate to every 10L seawater, wherein the ferric citrate needs to be heated to dissolve, and all reagents are mixed and dissolved before adding to the water pool.

[0007] Preferably, the partial death of benthic diatoms means the death of 30%-70% of the benthic diatoms, and more preferably the death of 40-60% of the benthic diatoms.

[0008] Preferably, the fertilized eggs of Trochus niloticus or Trochus pyramis Born;

[0009] Preferably, the aeration culture period is about 15 days.

[0010] The invention utilizes the sunlight exposure method to kill about 30%-70% of benthic diatoms while retaining some fresh benthic diatoms, thereby significantly improving the attachment, metamorphosis and survival of the horseshoe snail larvae and providing technical support for the large-scale production of horseshoe snails. DETAILED DESCRIPTION

[0011] The present invention is described in detail below in conjunction with specific embodiments, but is not intended to limit the present invention.

[0012] Example 1: Attachment metamorphosis and survival of giant horseshoe snail

[0013] In May 2023, two clean, transparent plastic films of 0.5m×0.5m were placed in two circular plastic barrels with a barrel mouth diameter and barrel height of 0.8m respectively. In order to make the plastic film sink, heavy objects (stones or discarded tiles, bricks, etc.) were wrapped in the middle, and filtered seawater was filled in. The water depth was 0.5m, and algae nutrient solution was added (for every 10L of seawater, 0.3g of sodium nitrate, 0.3g of urea, 0.05g of potassium dihydrogen phosphate, 0.005g of ferric citrate, and 0.05g of sodium silicate were added. The ferric citrate needed to be heated and dissolved. All reagents were mixed and dissolved and then added to the pool). The film was stirred evenly and aerated and cultured (10L / min). A black sunshade net needed to be installed above the pool to make the light intensity lower than 4500Lux. The culture seawater temperature was 28±0.5℃ and the salinity was 30ppt. After 15 days, it was found that the plastic film was covered with benthic diatoms. At 12:00 am the next day, the water in one of the plastic buckets was drained, the sunshade net was opened, and after being exposed to sunlight for a period of time, it was found that about 40% of the benthic diatoms died. Fresh filtered seawater (water depth 0.5m) was refilled and a sunshade net was installed as the experimental group. The other plastic bucket was used as the control group and no treatment was done. The fertilized giant horseshoe snail larvae were transferred to two plastic buckets respectively, and the culture density of the larvae was 0.1 / ml, and aeration was used for culture. After 3 days, it was found that the giant horseshoe snail larvae in the water body decreased significantly, and after 15 days, green seedlings were found attached to the plastic film and the bottom of the bucket. On the 16th day, the larvae attached to the two plastic buckets were counted, and it was found that the number of metamorphosed larvae attached to the giant horseshoe snails in the experimental group was about 2,500, while the number of metamorphosed larvae attached to the control group was about 250. After the statistics, the same volume of filtered seawater was refilled, the ventilation volume was increased (15L / min), and the water was cultured. If it is found during the culture process that 80% of the benthic diatoms are consumed, fresh benthic diatoms should be added in time.

[0014] Example 2: Attachment metamorphosis and survival of the pyramidal snail

[0015] In June 2023, two clean, transparent plastic films of 0.5m×0.5m were placed in two circular plastic barrels with a barrel mouth diameter and barrel height of 0.8m respectively, and heavy objects (stones or discarded tiles, bricks, etc.) were wrapped in the middle to make the plastic films completely immersed in seawater. Filtered seawater was filled in to a water depth of 0.5m, and algae nutrient solution was added (for every 10L of seawater, 0.3g of sodium nitrate, 0.3g of urea, 0.05g of potassium dihydrogen phosphate, 0.005g of ferric citrate, and 0.05g of sodium silicate were added, of which the ferric citrate needed to be heated and dissolved. All reagents were mixed and dissolved and then added to the pool), stirred evenly, and aerated and cultured (10L / min). A black sunshade net needed to be installed above the pool to make the light intensity lower than 4300Lux. The culture seawater temperature was 28±0.5℃, and the salinity was 30ppt. After 16 days, it was found that the plastic film was covered with benthic diatoms. At 12:00 am the next day, the water in one of the plastic buckets was drained, the sunshade net was opened, and after being exposed to sunlight for a period of time, it was found that about 60% of the benthic diatoms died. Fresh filtered seawater (water depth 0.5m) was refilled and a sunshade net was installed as the experimental group. The other plastic bucket was used as the control group and no treatment was done. The fertilized eggs of the pagoda-shaped horseshoe snails prepared in advance were transferred to the two plastic buckets respectively, and the culture density of the larvae was 0.1 / ml, and aeration culture was carried out. After 3 days, it was found that the pagoda-shaped horseshoe snail larvae in the water body decreased significantly. On the 15th day, white seedlings were found attached to the plastic film and the bottom of the bucket. On the 16th day, the larvae attached to the two plastic buckets were counted respectively, and it was found that the number of metamorphosed larvae attached to the pagoda-shaped horseshoe snails in the experimental group was about 2250, while the number of metamorphosed larvae attached to the control group was about 225. After the statistics, the same volume of filtered seawater was refilled, the ventilation volume was increased (15L / min), and the water was cultured. If it is found during the culture process that 80% of the benthic diatoms are consumed, fresh benthic diatoms should be added in time.

Claims

1. A method for improving the survival of horse snail seedlings, characterized in that: Place plastic film or corrugated board in the pool, add algae nutrient solution, stop running water, aerate and cultivate for 15-30 days, install black sunshade net above the pool to make the light intensity lower than 5000Lux, the temperature of the culture water body is 20-30℃, and the salinity is 30-32ppt. After the benthic diatoms are fully grown, drain all the water in the pool, open the sunshade net, and expose the benthic diatoms to the sun. When some of the benthic diatoms die, add water to the pool for ventilation, re-lay the sunshade net, and then move the fertilized eggs of horseshoe snails into the diatom pool after exposure, stop running water, and aerate and cultivate.

2. The method according to claim 1, characterized in that The algae nutrient solution ratio is: add 0.3g sodium nitrate, 0.3g urea, 0.05g potassium dihydrogen phosphate, 0.005g ferric citrate, and 0.05g sodium silicate to every 10L seawater, wherein the ferric citrate needs to be heated to dissolve, and all reagents are mixed and dissolved and then added to the water pool.

3. The method according to claim 1, characterized in that: The partial death of benthic diatoms refers to the death of 30%-70% of benthic diatoms.

4. The method according to claim 3, characterized in that The partial death of benthic diatoms refers to the death of 40-60% of benthic diatoms.

5. The method according to claim 1, characterized in that The fertilized eggs of Trochus niloticus are fertilized eggs of Trochus niloticus or Trochus pyramis Born.

6. The method according to claim 1, characterized in that The aeration culture period is 15 days.