Seawater pond ecological polyculture method capable of efficiently utilizing nutrient substances

Abstract

The invention discloses a seawater pond ecological polyculture method capable of efficiently utilizing nutrient substances. Through the technical links of seawater pond physicochemical condition investigation, polyculture variety selection, fry throwing time, density and the like selection, water quality ecological regulation and control, scientific management of the ecological polyculture process, culture harvesting and the like, the current situation that more traditional physicochemical methods are used for treating the culture tail water is changed, and the biological treatment of the culture tail water with low cost and good effect is realized; meanwhile, high utilization rate, high growth speed, high yield, high benefit, low disease outbreak rate, low death rate and the like of the water body of the seawater pond are also remarkably promoted, and the defects of pure shrimp or pure shellfish culture are effectively overcome; the win-win situation that nutrient substances are efficiently utilized, shrimp culture tail water discharge reaches the standard and shrimp and shellfish culture benefits are improved is achieved, a new technical thought is provided for sustainable and green aquaculture development, and the method is an excellent ecological polyculture mode high in repeatability and good in application effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aquaculture technology in marine agriculture, and particularly relates to a seawater pond ecological mixed culture method with high efficiency of nutrient utilization. BACKGROUND

[0002] In recent years, with the attention of the state to marine environmental protection, the traditional single-species breeding mode, especially the high-density breeding and high-level pond breeding of marine shrimp, faces the current situation of single trophic level, high density, high feeding amount, high residual bait, high water exchange, high pollution, high disease outbreak rate, etc., which leads to a series of industrial problems such as slow growth, high mortality, high pollution to seawater, low yield, low output value, low benefit, frequent disease outbreak, etc. of marine shrimp breeding industry, especially the discharge of shrimp tail water to the eutrophication of nearshore seawater and the pollution of beach, the environmental protection pressure leads the government to strictly control the breeding area of marine shrimp, which further has an important impact on the marine shrimp breeding industry. The traditional tail water treatment methods such as "three ponds and two dams", "suspended biological bed" and "integrated equipment" all face the problems of high investment, high maintenance cost, poor treatment effect and poor long-term operation feasibility, etc. in tail water treatment, which makes it difficult for the above-mentioned methods to be implemented for a long time. The marine shrimp pond breeding urgently needs a reliable biological method to ecologically treat the shrimp tail water, which can not only achieve the effect of low-cost tail water treatment, but also improve the breeding benefit. At the same time, in recent years, with the rapid expansion of breeding area and density, shellfish breeding, especially filter-feeding shellfish breeding, faces the problems of lack of seawater microalgae, poor condition, slow growth and high mortality, which further leads to low price, poor quality and low benefit, seriously restricting the sustainable development of shellfish breeding. Shellfish breeders hope to find a low-cost and short-time breeding method to improve the condition and growth rate and reduce the mortality rate to improve the benefit of shellfish breeding. SUMMARY

[0003] The purpose of the present application is to provide a multi-trophic level ecological mixed culture method with high efficiency of nutrient utilization in seawater pond, which can not only reduce the frequency of disease outbreak, mortality, yield, and pollution of shrimp breeding tail water, but also accelerate the growth of shellfish breeding, improve the condition, and reduce the mortality.

[0004] The present application is mainly about a seawater pond ecological mixed culture method with high efficiency of nutrient utilization, which comprises seawater pond physicochemical condition investigation, mixed culture species selection, stocking time, density selection, water quality ecological regulation, scientific management of ecological mixed culture process and breeding harvest, and is characterized by comprising the following steps:

[0005] a. Investigation of the physical and chemical conditions of seawater ponds: The physical and chemical conditions of different seawater ponds directly determine the species composition, stocking density, stocking time, and yield of shrimp and shellfish ecological aquaculture. Therefore, it is necessary to conduct a systematic investigation of the physical and chemical conditions of seawater ponds, track and measure the variation range and period of key physical and chemical factors, and fully understand the physical and chemical conditions of seawater ponds where ecological aquaculture is to be carried out;

[0006] b. Selection of mixed culture species: Based on the results of the physical and chemical condition investigation in a, select appropriate ecological mixed culture species according to the upper, middle, and lower layers;

[0007] Upper layer shrimp: low salt species, high salt species, low temperature species, wide temperature species, and high temperature species;

[0008] Middle layer of hanging culture shellfish: low salt species, high salt species, wide salt species, low temperature species, high temperature species, wide culture area, and large culture area;

[0009] Bottom layer of benthic shellfish: sandy bottom, muddy bottom, wide temperature species, high temperature species, low temperature species, high salt species, low salt species, and wide salt species, wide culture area, and large culture area;

[0010] c. Selection of stocking time, density, etc.: Based on the variation of physical and chemical conditions in a and the selection of mixed culture species in b, the stocking time, density, and species need to be matched. Based on seawater aquaculture ponds in the south or north, the stocking time can be selected as follows: in the north, from April to June; in the south, from March to September. The order of stocking seed is upper layer planktonic shrimp, bottom layer benthic shellfish, and middle layer hanging culture shellfish. The type of attachment substrate for middle layer shellfish needs to be selected based on water depth. For water depth greater than 3 meters, cement cake, cement board, scallop shell, or oyster shell is needed. For water depth less than 3 meters, cement cake, scallop shell, or oyster shell is needed. The stocking density needs to be determined based on the area and water depth of the seawater pond. When the water depth is greater than 3 meters and the seawater pond area is greater than 3 mu, the stocking density of upper layer planktonic shrimp is 30,000 individuals per mu, the stocking density of middle layer hanging culture shellfish is 120 hanging per mu (about 100 seedlings per hanging), and the stocking density of bottom layer benthic shellfish is 25,000 individuals per mu (seedlings after medium cultivation). When the water depth is less than 3 meters and the seawater pond area is less than 3 mu, the stocking density of upper layer planktonic shrimp is 12,000 individuals per mu, the stocking density of middle layer hanging culture shellfish is 40 hanging per mu (about 100 seedlings per hanging), and the stocking density of bottom layer benthic shellfish is 10,000 individuals per mu (seedlings after medium cultivation);

[0011] d. Water quality ecological regulation: Ecological mariculture ponds need to be water quality regulation and reasonable fertilizer, mainly to cultivate green algae, diatoms and other microalgae and some beneficial bacteria Bacillus, nitrifying bacteria, photosynthetic bacteria, etc., preferably in 3 days before the seed release need to start water, mainly every 5 days to put water special nitrogen, phosphorus and potassium compound fertilizer (nitrogen, phosphorus and potassium ratio of 5:3:2) 1 kg / mu, every 2 days to put diatom algae powder 50 g / mu, green algae powder 50 g / mu, concentrated chlorella paste 150 mL / mu, every 2 days to put complex bacteria 300 mL / mu, put the above material on the day without water and need to increase the oxygenation time, in order to facilitate the small microalgae and beneficial bacteria reproduction;

[0012] e. Scientific management of ecological aquaculture process: Scientific management of ecological aquaculture process is very important, mainly involves disinfection, oxygenation, fertilization, Ph adjustment, water change, feed adjustment, and inhibition of harmful organisms, etc. Preferably, in terms of disinfection, before putting the seed, the seawater pond needs to be completely dredged, disinfected with quicklime or bleaching powder, and then watered after 7-10 days of sun exposure. After watering, the seawater physicochemical factors are detected and suitable, and then the seed is put in after 2-3 days. In terms of oxygenation, the oxygenation machine needs to be turned on at 6-8 am, 12-14 pm and 17-19 pm every day, and 2-4 hours more in rainy weather. The oxygen content in the water is detected regularly to ensure that the upper layer contains 6-8 mg / L of oxygen. In terms of fertilization, attention should be paid to controlling the amount of fertilization, and NP, ammonia nitrogen, etc. should be detected regularly. In terms of Ph, seawater Ph should be detected regularly to ensure that the seawater pond Ph is 7.0-9.0, showing weak alkaline. If the Ph is too low, quicklime can be appropriately splashed, and if the Ph is too high, the use of fertilizer can be reduced and the water change frequency can be increased. In terms of water change, the amount of water change for shrimp and shellfish ecological mariculture ponds needs to be reduced, and the amount of water change needs to be increased only in the case of poor water quality. In terms of feed, the amount of feed also needs to be adjusted reasonably. Too little feed will affect the growth of organisms, and too much feed will spoil the water quality and increase costs (although shellfish can filter and use some leftover feed, too much feed is still harmful and useless). The principle of precise feeding needs to be followed, which is "timing, fixed point, fixed quantity, monitoring, and adjustment". After feeding at a fixed time, fixed point, and fixed quantity, the amount of leftover feed in the seawater pond is monitored 2 hours later, and the amount of feed is adjusted appropriately. In terms of inhibiting harmful organisms, the main ones are cyanobacteria, large green algae, filamentous algae, carnivorous fish, crabs, barnacles, and small mussels. The above harmful organisms will compete for nutrients, spoil the water quality, and kill shrimp and shellfish, etc. Therefore, the amount of water change needs to be controlled, the changed seawater needs to be disinfected in advance, and blue algae inhibitors need to be splashed in time.

[0013] f. Harvesting: The harvesting of the catch in ecological mariculture ponds needs to follow the order of upper layer shrimp, middle layer hanging shellfish, and bottom layer bottom shellfish in order to achieve effective treatment of the tail water, green aquaculture, and efficient use of nutrients.

[0014] After the above steps, compared with single shrimp culture pond, the tail water pollution index of ecological mixed culture seawater pond is significantly reduced, and the transparency is improved, the pathogenic microorganisms of shrimp are reduced, the mortality rate of shrimp is reduced, the yield and benefit of shrimp are improved, the nitrogen and phosphorus content is reduced, etc. Compared with single shellfish culture pond, the shellfish grows faster, the fullness is better, and the mortality rate is lower. The method of shrimp-shellfish mixed culture has the advantages of efficient utilization of nutrients, significant improvement of yield and benefit, high quality of cultured products, ecological regulation to make the tail water meet the standard, low cost and sustainable tail water treatment, etc.

[0015] Preferably, the tracking measurement and comprehensive understanding of the physicochemical conditions of the seawater pond refers to tracking the changes of the physicochemical factors of the seawater pond for at least 6 months, especially in the south, tracking across the rainy season to obtain the change range of the physicochemical factors including the rainy season period.

[0016] Preferably, the physicochemical conditions of the seawater pond refer to salinity, temperature, bottom, area, water depth, tidal water inflow and outflow, microbial composition, etc., which will directly affect the smooth implementation of ecological mixed culture.

[0017] Preferably, the shellfish in b must be filter-feeding shellfish, and it is mainly the species with high economic value and mainly cultured, especially the shellfish hung in the middle layer, which is preferably filter-feeding shellfish, so it can only refer to oysters or mussels.

[0018] Preferably, the high-salt species in b refers to the species that can grow and survive well at salinity of 20‰-35‰, the low-salt species refers to the species that can grow and survive well at salinity of 5‰-20‰, the euryhaline species refers to the species that can grow and survive normally at 5‰-35‰; the high-temperature species refers to the species that can grow and survive well at temperature higher than 25℃ in the south, the low-temperature species refers to the species that can grow and survive well at temperature lower than 25℃ in the north, the eurythermal species refers to the species that can grow and survive normally in the seawater temperature in the south and north of China; large cultivation area refers to the seawater pond with cultivation area more than 3 mu, and small cultivation area refers to the seawater pond with cultivation area less than 3 mu; sandy bottom mainly refers to the seawater pond with sand as the main bottom, and a small amount of mud, and muddy bottom refers to the seawater pond with mud as the main bottom, and a small amount of sand.

[0019] Upper layer shrimp: low-salt species can be Penaeus vannamei, high-salt species can be Marsupenaeus japonicus; low-temperature species can be Chinese Litopenaeus vannamei, Japanese Litopenaeus vannamei, eurythermal species can be Penaeus vannamei, high-temperature species can be Marsupenaeus japonicus;

[0020] The middle layer of the hanging culture of shellfish: low salt species can be Hong Kong oysters, Kumamoto oysters, high salt species can be Pacific oysters, Portuguese oysters, Aesop oysters, rock oysters, purple mussels, thick shell mussels, jade mussels, wide salt species can be Dianbai oysters, Kino oysters, monk oysters; low temperature species can be Pacific oysters, rock oysters, purple mussels, thick shell mussels, high temperature species can be Portuguese oysters, Hong Kong oysters, Dianbai oysters, Aesop oysters, Kino oysters, Kumamoto oysters, monk oysters, jade mussels; wide cultivation area can be Portuguese oysters, Kumamoto oysters, monk oysters, Hong Kong oysters, Dianbai oysters, Aesop oysters, Kino oysters, wide cultivation area can be Pacific oysters, rock oysters, purple mussels, thick shell mussels, jade mussels.

[0021] Preferably, the selection of the upper layer, the middle layer and the bottom layer in b must meet the requirements of the physicochemical conditions of the seawater pond, such as salinity, temperature, substrate and cultivation area.

[0022] Preferably, the north in c refers to the seawater ponds in Liaoning, Shandong, Hebei, Jiangsu, Zhejiang and other sea areas, and the south refers to the seawater ponds in Fujian, Guangdong, Guangxi and Hainan sea areas; the time of releasing fry needs to consider the growth period of high temperature period, so the release of fry generally needs to be in the period of high temperature, so the north generally releases fry in April to June, which just goes through the high-speed growth period of shrimp and shellfish from June to October.

[0023] Preferably, the reason for releasing fry in the order of upper layer planktonic shrimp, bottom layer benthic shellfish and middle layer hanging type shellfish in c is that shellfish is mainly filter-feeding shellfish, and the release of upper layer planktonic shrimp will produce residual feed, which will ferment and cause the increase of microalgae, microorganisms and small particles, so that filter-feeding shellfish will have sufficient food source.

[0024] Preferably, the type of the attachment base for the middle layer of the hanging culture of shellfish based on water depth in c is due to the different weights and lengths of different attachment bases, which need to prevent the attachment base from falling to the bottom to cause poor growth of the hanging shellfish; cement cake and square plate are generally heavy and long, suitable for use in seawater ponds with water depth greater than 3 meters, cement rope is light and short, suitable for use in seawater ponds with water depth less than 3 meters, and scallop shell and oyster shell attachment base can flexibly adjust the length of the rope according to the water depth.

[0025] Preferably, the density of releasing fry in c needs to be adjusted according to the actual water depth and area of the seawater pond, and the reason for the lower density of the middle layer of the hanging type shellfish and the bottom layer of the bottom type shellfish than the single shellfish cultivation seawater pond is to avoid the competition of the middle and bottom layer of filter-feeding shellfish.

[0026] Preferably, the water quality control and fertilization in d is mainly through the cultivation of planktonic microalgae and beneficial bacteria in seawater, which can stabilize water quality, increase oxygen supply, provide natural food source and reduce disease occurrence.

[0027] Preferably, the amount of water quality control and fertilizer water required to be put in d is only applicable to the continuous good weather, when the continuous rainy weather is more than 7 days, the amount of put-in material needs to be doubled.

[0028] Preferably, the amount of quicklime or bleaching powder used for water quality disinfection in e is 30 kg / acre, and the purpose of disinfection and sunning is to kill bacteria and other microorganisms, algae, barnacles, small shellfish, fish, etc.; the reason for reducing the water exchange is that the shrimp and shellfish ecological aquaculture pond is relatively stable in water quality due to the filter-feeding of shellfish on residual feed, small particles and microorganisms, etc., and also for the filter-feeding shellfish to more effectively utilize the residual feed, green cultivation, reduce costs and reduce biological stress caused by water exchange, etc.

[0029] Preferably, the purpose of the timed, fixed-point and quantitative feeding in e is to make shrimp develop conditioned reflex, improve feed utilization rate, and facilitate monitoring and adjustment of feed amount; blue-green algae and large algae mainly compete with microalgae for nutrients such as nitrogen and phosphorus, and their outbreak will inevitably lead to the decline of small microalgae such as green algae and diatoms, causing water quality damage, increased mortality of shellfish due to lack of feed, and other adverse consequences.

[0030] Preferably, the order of cultivation and harvesting in f is to harvest the middle and bottom shellfish 10-15 days after harvesting the upper planktonic shrimp, so that residual feed, small particles and microorganisms can be better utilized by filter-feeding shellfish, achieving the goals of efficient utilization of nutrients, green cultivation and tail water discharge compliance.

[0031] The multi-trophic level cultivation method of utilizing filter-feeding shellfish and shrimp to carry out efficient utilization of nutrients is a method with great potential for ecological mixed cultivation, which can effectively solve the problems faced by shrimp and shellfish cultivation. Through this method, on the one hand, shellfish can effectively filter residual feed, purify water quality, increase seawater transparency, reduce disease outbreaks, reduce mortality, reduce the nitrogen and phosphorus content of tail water, etc. by filtering seawater, microorganisms, small planktonic particles, microalgae, etc. On the other hand, the residual feed produced by shrimp cultivation, microalgae and microorganisms that reproduce due to high nitrogen and phosphorus can provide a large amount of food source for the growth of shellfish, thereby causing the shellfish to grow faster, improve the degree of fatness, and have low mortality. The rational combination of the above-mentioned shrimp and shellfish cultivation forms a multi-trophic level cultivation mode, achieving efficient utilization of nutrients, tail water discharge compliance of shrimp cultivation, and the win-win situation of improved benefits of shrimp and shellfish cultivation. It is a typical multi-trophic level ecological mixed cultivation method of efficient utilization of nutrients. However, the scale application and implementation of this method needs to consider species selection, water quality control, enemy organisms (large algae outbreak, etc.), cultivation technology management, cultivation product harvesting, etc. based on the seawater environment, which are also the key technical points of this invention.

[0032] The present application is based on a series of industrial problems of single shrimp mariculture in seawater ponds, such as high mortality, great pollution to seawater, low yield, low output value, frequent disease outbreaks, great eutrophication of nearshore seawater and beach pollution caused by discharge of shrimp culture tail water, and great difficulty in treatment of culture tail water, poor sustainability and high cost of existing treatment methods, and industrial problems of single shellfish mariculture in seawater ponds, such as poor water utilization, oligotrophic water quality, shortage of bait, great difficulty in fertilization, high mortality, slow growth and low efficiency, and a multi-trophic level ecological mixed culture method with high efficient utilization of nutrients is improved, which changes the present situation of more relying on physical and chemical methods to treat culture tail water, and realizes biological treatment of culture tail water with low cost and good effect, and also significantly helps to achieve high utilization rate of seawater pond water, high growth rate, high yield, high efficiency, low disease outbreak rate and low mortality. Although there have been some reports on shrimp and shellfish mixed culture, the technical methods are not mature, the program research is not systematic, the species matching is unreasonable, the variety selection is complex, the utilization efficiency is not high, and the method operation is difficult, which leads to poor effect and restricts the popularization and use, but the present application effectively solves the above technical defects, realizes the efficient utilization of nutrients, and achieves the win-win situation of shrimp culture tail water discharge reaching the standard and the improvement of shrimp and shellfish culture benefits, and provides a new technical idea for the development of sustainable and green aquaculture.

[0033] Compared with single shrimp culture, the growth rate of ecological mixed culture shrimp is increased by 23.55%, the mortality is reduced by 40.24%, the yield is increased by 33.85%, and the efficiency is increased by 33.85%; compared with single shellfish culture, the growth rate of ecological mixed culture shellfish is increased by 30.00%, the mortality is reduced by 47.25%, the yield is increased by 30.68%, and the efficiency is increased by 30.64%; compared with single shellfish culture, the growth rate of ecological mixed culture shellfish is increased by 16.34%, the mortality is reduced by 39.57%, the yield is increased by 9.63%, and the efficiency is increased by 9.63%; compared with single shrimp culture, the total efficiency of ecological mixed culture is increased by 112.30%; compared with single shellfish culture, the total efficiency of ecological mixed culture is increased by 204.42%. The present application provides a specific operation method and reference index of multi-trophic level ecological mixed culture with high efficient utilization of nutrients.

[0034] The present application has the advantages of strong operability, simplicity, great commercial application potential and the like. DETAILED DESCRIPTION

[0035] The following examples are further illustrations of the present application, and are not intended to limit the present application.

[0036] Example 1

[0037] a, Investigation of the physicochemical conditions of seawater ponds: In June 2023, an ecological aquaculture experiment was conducted in a seawater pond near Pearl Bay in Fangcheng District, Fangchenggang City, Guangxi. The physicochemical factors of the seawater pond had been monitored for one year in the early stage. It was found that the salinity of the seawater pond was 12.5‰-19.8‰, the temperature was 16.8℃-32.3℃, the bottom material was sandy, the area of a single pond was about 5 mu, the water depth was about 3-5 meters, the seawater could enter and exit normally according to the tides every day, the surrounding ponds mainly cultured oysters, South American white shrimps and fish, and the microbial composition of the seawater pond was found to be Proteus, Psychrobacter, Synechococcus, Micrococcus, and Microaerophilic Actinomyces, etc. No large amount of harmful bacteria was found.

[0038] b, Selection of mixed culture species: Based on the above investigation results of physicochemical factors, the selected and matched aquaculture species in the ecological aquaculture seawater pond were upper layer planktonic shrimp—South American white shrimp, middle layer filter-feeding mollusk—Hong Kong oyster and Dianbai oyster, and bottom layer benthic mollusk—undulate lutea. The seawater pond for pure shrimp culture was South American white shrimp, and the seawater pond for pure mollusk culture was Hong Kong oyster, Dianbai oyster and undulate lutea.

[0039] c, Selection of stocking time and density, etc.: After adding seawater, 30,000 South American white shrimp fry per mu were simultaneously released in the ecological aquaculture group and the pure shrimp culture group on June 5. The shrimp fry was checked for good health status and vitality before purchase, transported with cold chain transportation to maintain a temperature of 13-18℃ and sufficient oxygen during transportation, and then placed in the seawater pond for 30 minutes before being gently released into the seawater. 25,000 undulate lutea fry per mu were simultaneously released in the ecological aquaculture group and the pure mollusk culture group on June 10. The undulate lutea fry was checked for health status and uniformity in size before release, and the post-cultivation fry was transported with 8-12℃ cold chain transportation. The fry was placed in seawater for 1 hour before being evenly scattered in the seawater pond. 60 Hong Kong oyster and Dianbai oyster fry per mu were simultaneously released in the ecological aquaculture group and the pure mollusk culture group on June 15, with 7 pieces of cement jellyfish cake attached to each group. The released oyster fry had uniform density and individual size of 5-8mm, and was transported with 10-15℃ cold chain transportation. The aquaculture salinity was adjusted to be consistent with the seawater pond 3 days before transportation, and the oyster fry was vertically hung on the floating raft with a spacing of 60cm and a hanging depth of 80cm from the surface.

[0040] d, Ecological regulation of water quality: Fertilization should start 3 days before fry release. Nitrogen, phosphorus and potassium compound fertilizer (nitrogen, phosphorus and potassium ratio of 5:3:2) 1kg / mu was released every 5 days, diatom algal powder 50g / mu, green algal powder 50g / mu and concentrated chlorella paste 150mL / mu were released every 2 days, and compound bacterial agent 300mL / mu was released every 2 days. The water was not changed on the day of releasing the above materials and the oxygenator was turned on for 2 hours immediately.

[0041] e. Scientific management of ecological aquaculture process: The scientific management of pure shrimp culture, pure shellfish culture and ecological aquaculture pond should be consistent, and the consistency of the material and the unity of the physical and chemical factors should be ensured. Before adding seawater to the seawater pond, the artificial preliminary cleaning of sundries, picking up fish, shrimp and shellfish, removing barnacles, small mussels and other attached materials on the pond, and then using excavator to turn over the sand on the pond bottom and the shore, removing weeds, turning over the silt, regularizing the pond, etc. Then 30 kg of bleaching powder per mu is used to thoroughly disinfect the pond bottom and the shore, completely empty the pond and expose it to the sun for 10 days before starting to add seawater. The seawater needs to be aerated, the residual bleaching powder needs to be detected, and it needs to be left for 2 days. In terms of oxygenation, the aerator needs to be turned on at 6-8 am, 12-14 pm and 17-19 pm every day, and in rainy weather, the aerator needs to be turned on for 3 hours in the evening. The oxygen content in the water needs to be detected regularly to ensure that the oxygen content in the upper layer is 6-8 mg / L. According to the special nitrogen, phosphorus and potassium compound fertilizer for shrimp pond, the nitrogen, phosphorus and ammonia nitrogen in the ecological aquaculture seawater pond are detected in time to adjust the amount of compound fertilizer. The seawater Ph is detected regularly to ensure that the seawater pond Ph is 7.0-9.0, showing weak alkaline, and Ph is too low, which can be appropriately sprinkled with quicklime, and Ph is too high, which can reduce the use of fertilizer and increase the frequency of water change. Pure shrimp culture, pure shellfish culture and ecological aquaculture pond should be changed every 7 days, 5%. When the water quality needs to be improved, the three groups of water change amount need to be consistent. Pure shrimp culture and ecological aquaculture pond need to be fed with shrimp feed, and pure shellfish culture pond does not need to be fed with shrimp feed. The feeding of shrimp feed follows the principle of "fixed time, fixed point, fixed quantity, monitoring and adjustment", and 2 hours after the fixed time, fixed point and fixed quantity of feeding are adjusted according to the residual bait in the seawater pond. Regularly use filter net to salvage blue-green algae, filamentous algae and large green algae to prevent their large-scale reproduction from affecting water quality and competing for nutrients. When changing water, the seawater needs to be disinfected, the net bag needs to be filtered, and the artificial cleaning needs to be avoided to prevent enemy organisms and fouling organisms from entering the seawater pond. According to the water quality, water quality improvement agent, blue-green algae inhibitor and fertilizer cream are sprayed synchronously.

[0042] f. Cultivation and harvesting: During the cultivation process, the growth and survival of shrimp and shellfish are measured every 30 days. On October 10, shrimp in the seawater pond are caught with a net and their size and weight are counted. On October 25, shellfish are harvested, and their shell height, total weight, meat weight, fullness and yield are measured. According to market prices, the benefits are preliminarily estimated.

[0043] Through the statistics of the growth data and the harvest quantity, it is found that, as shown in Table 1, compared with the shrimp culture alone, the growth rate of the ecological mixed culture shrimp is increased by 23.55%, the mortality is reduced by 40.24%, the yield is increased by 33.85%, and the benefit is increased by 33.85%; compared with the shellfish culture alone, the growth rate of the ecological mixed culture shellfish is increased by 30.00%, the mortality is reduced by 47.25%, the yield is increased by 30.68%, and the benefit is increased by 30.64%; compared with the shellfish culture alone, the growth rate of the ecological mixed culture benthic shellfish is increased by 16.34%, the mortality is reduced by 39.57%, the yield is increased by 9.63%, and the benefit is increased by 9.63%; compared with the shrimp culture alone, the total benefit of the ecological mixed culture is increased by 112.30%; compared with the shellfish culture alone, the total benefit of the ecological mixed culture is increased by 204.42%.

[0044] Table 1 related parameters of each group at harvest

[0045]

[0046]

Claims

1. A method for high-efficiency utilization of nutrients in a marine pond ecological aquaculture, characterized in that it comprises the following steps: a. Investigation of the physicochemical conditions of the marine pond: The physicochemical conditions of different marine ponds directly determine the species composition, stocking density, stocking time and yield harvesting of shrimp and shellfish ecological aquaculture. Therefore, it is necessary to carry out a systematic investigation of the physicochemical conditions of the marine pond, track and measure the variation range and period of key physicochemical factors, and fully understand the physicochemical conditions of the marine pond where ecological aquaculture is to be carried out; b. Selection of mixed culture species: According to the results of the physicochemical condition investigation in a, select and match suitable ecological aquaculture species according to the upper, middle and lower layers; upper layer shrimp: low salt species, high salt species, low temperature species, wide temperature species and high temperature species; middle layer hanging culture shellfish: low salt species, high salt species, wide salt species, low temperature species, high temperature species, wide culture area and large culture area; bottom layer benthic shellfish: sandy bottom, muddy bottom, wide temperature species, high temperature species, low temperature species, high salt species, low salt species, wide salt species, wide culture area and large culture area; c. Selection of stocking time and density: Based on the physicochemical condition changes in a and the mixed culture species selection in b, the stocking time, density and species need to be matched. Based on the marine aquaculture ponds in the south or north, the stocking time is selected, the north can be stocked in April to June, and the south can be stocked in March to September. The seed needs to be stocked in the order of upper layer planktonic shrimp, bottom layer benthic shellfish and middle layer hanging culture shellfish. The type of substrate for middle layer shellfish needs to be selected based on water depth. Cement cake, cement board, scallop shell or oyster shell need to be selected when the water depth is greater than 3 meters, and cement cake, scallop shell or oyster shell need to be selected when the water depth is less than 3 meters; d. Ecological regulation of water quality: The marine pond for ecological aquaculture needs water quality regulation and reasonable fertilization, mainly cultivating green algae, diatoms and other microalgae, and some beneficial bacteria such as Bacillus, nitrifying bacteria and photosynthetic bacteria; e. Scientific management of ecological aquaculture process: Scientific management during the ecological aquaculture process is very important, mainly involving disinfection, oxygenation, fertilization, Ph adjustment, water exchange, feed adjustment, and harmful organism control; f. Harvesting: The harvesting of the marine pond for ecological aquaculture needs to follow the harvesting order of upper layer shrimp, middle layer hanging culture shellfish and bottom layer benthic shellfish in order to achieve effective treatment of tail water, green aquaculture and high-efficiency utilization of nutrients. The physicochemical conditions in step a need to track the changes of physicochemical factors in the marine pond for more than 6 months, especially in the south, the changes of physicochemical factors need to be tracked across the rainy season, including the variation range of physicochemical factors during the rainy season. Preferably, the physicochemical conditions refer to salinity, temperature, substrate, area, water depth, tidal water inflow and outflow, and microbial composition. The shellfish in step b must be filter-feeding shellfish, and they need to have high economic value and be mainly cultured species. Especially, the middle layer hanging culture shellfish should be better filter-feeding shellfish, specifically oysters or mussels. ​ ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein, ​ 3. The method of claim 1, wherein, ​ 4. The method of claim 1, wherein, The high salt species in step b refers to the species that can grow and survive well at salinity of 20‰-35‰, the low salt species refers to the species that can grow and survive well at salinity of 5‰-20‰, the euryhaline species refers to the species that can grow and survive normally at salinity of 5‰-35‰; the high temperature species refers to the species that can grow and survive well at temperature higher than 25℃ in the south, the low temperature species refers to the species that can grow and survive well at temperature lower than 25℃ in the north, the eurythermal species refers to the species that can grow and survive normally at water temperature in the south and the north of China; the large breeding area refers to the marine pond with the breeding area larger than 3 mu, and the small breeding area refers to the marine pond with the breeding area smaller than 3 mu; the sandy bottom mainly refers to the marine pond with sand as the main bottom, and a small amount of mud, and the muddy bottom refers to the marine pond with mud as the main bottom, and a small amount of sand.

5. The method according to claim 1 or 4, characterized in that, The mixed breeding species in step b is selected as follows: The upper layer shrimp: the low salt species can be Penaeus vannamei, and the high salt species can be Marsupenaeus japonicus; The middle layer shellfish: the low salt species can be Crassostrea hongkongensis and Crassostrea ikedai, the high salt species can be Crassostrea gigas, Crassostrea angulata, Crassostrea iredalei, Crassostrea sikamea, Mytilus galloprovincialis, Mytilus edulis, the euryhaline species can be Crassostrea electrica, Crassostrea pemaica, Ostrea denselamellosa, and the low temperature species can be Crassostrea gigas, Crassostrea iredalei, Mytilus edulis, and the high temperature species can be Crassostrea angulata, Crassostrea hongkongensis, Crassostrea electrica, Crassostrea ikedai, Crassostrea pemaica, Crassostrea sikamea, and the eurythermal species can be Crassostrea angulata, Crassostrea hongkongensis, Crassostrea electrica, Crassostrea ikedai, Crassostrea pemaica, Crassostrea sikamea, and the wide breeding area species can be Crassostrea angulata, Crassostrea hongkongensis, Crassostrea electrica, Crassostrea ikedai, and the large breeding area species can be Crassostrea gigas, Crassostrea iredalei, Mytilus edulis, and Mytilus galloprovincialis; The bottom layer shellfish: the sandy bottom species can be Ruditapes philippinarum, Paphia undulata, Meretrix meretrix, Mactra veneriformis, Sinonovacula constricta, Cyclotellan fluminea, and the muddy bottom species can be Sinonovacula constricta and Batillaria zonalis, and the eurythermal species can be Meretrix meretrix and Sinonovacula constricta, and the high temperature species can be Paphia undulata, Mactra veneriformis, Batillaria zonalis, and the low temperature species can be Ruditapes philippinarum and Cyclotellan fluminea, and the high salt species can be Ruditapes philippinarum, Paphia undulata, and Batillaria zonalis, and the low salt species can be Meretrix meretrix, and the euryhaline species can be Mactra veneriformis, Sinonovacula constricta, and Cyclotellan fluminea, and the wide breeding area species can be Ruditapes philippinarum, Paphia undulata, Meretrix meretrix, and Mactra veneriformis, and the large breeding area species can be Sinonovacula constricta, Batillaria zonalis, Cyclotellan fluminea, and Sinonovacula constricta.

6. The method of claim 1, wherein, The selection of the upper layer, the middle layer and the bottom layer species in step b must meet the requirements of the physical and chemical conditions of the marine pond, such as salinity, temperature, bottom, breeding area, etc.

7. The method of claim 1, wherein, The density of the seedling is determined according to the area and water depth of the seawater pond, when the water depth is greater than 3 meters and the seawater pond area is greater than 3 mu, the density of the upper layer of planktonic shrimp seedlings is 30,000 per mu, the density of the middle layer of hanging type shellfish is 120 per mu, about 100 seedlings per hanging, and the density of the bottom layer of benthic type shellfish is 25,000 per mu after the seedlings are cultured in the middle; when the water depth is less than 3 meters and the seawater pond area is less than 3 mu, the density of the upper layer of planktonic shrimp seedlings is 12,000 per mu, the density of the middle layer of hanging type shellfish is 40 per mu, about 100 seedlings per hanging, and the density of the bottom layer of benthic type shellfish is 10,000 per mu after the seedlings are cultured in the middle.

8. The method of claim 1, wherein, The water quality control and fertilization in step d need to start 3 days before the seedlings are put in, mainly every 5 days, put nitrogen, phosphorus and potassium compound fertilizer for fertilization, the ratio of nitrogen, phosphorus and potassium is 5:3:2, 1 kg per mu, every 2 days, put diatom algae powder 50 g per mu, green algae powder 50 g per mu, and concentrated chlorella paste 150 mL per mu, every 2 days, put compound bacterial agent 300 mL per mu, the day of putting the above materials, do not change water and need to increase the oxygenation time, so as to facilitate the reproduction of small microalgae and beneficial bacteria; if the continuous rainy weather is more than 7 days, the amount of the materials needs to be doubled.

9. The method of claim 1, wherein, In step e, in terms of disinfection, before putting the seedlings, the seawater pond needs to be completely dredged, disinfected with quicklime or bleaching powder, and sun dried for 7-10 days before water is put in, after the water is put in, the seawater physical and chemical factors are detected and suitable, and the seedlings are put in after standing for 2-3 days; in terms of oxygenation, the oxygenation machine needs to be started at 6-8 am, 12-14 pm and 17-19 pm every day, and 2-4 hours more in rainy weather, the oxygen content in the water is regularly detected to ensure that the oxygen content in the upper and middle layers is 6-8 mg / L; in terms of fertilization, attention needs to be paid to controlling the amount of fertilization, and NP, ammonia nitrogen, etc. are regularly detected; in terms of Ph, the seawater Ph is regularly detected to ensure that the seawater pond Ph is 7.0-9.0, showing weak alkaline, if the Ph is too low, quicklime can be appropriately splashed, if the Ph is too high, the amount of fertilizer can be reduced, and the frequency of water change can be increased; in terms of water change, the amount of water change needs to be reduced, 5%-10% every 7 days, and the amount of water change can be appropriately increased in the case of poor water quality; in terms of bait feeding, the amount of bait feeding also needs to be reasonably adjusted, too little bait feeding will affect the growth of organisms, too much bait feeding will deteriorate the water quality and increase the cost (although shellfish can filter and use some residual bait, too much bait feeding is still harmful and useless), the principle of precise feeding of "fixed time, fixed point, fixed amount, monitoring and adjustment" needs to be followed, 2 hours after the bait is fed at fixed time, fixed point and fixed amount, the amount of residual bait in the seawater pond is monitored, and the amount of bait feeding is appropriately and reasonably adjusted; in terms of inhibiting harmful organisms, mainly need to inhibit blue-green algae, large green algae, filamentous algae, carnivorous fish, crabs, barnacles, small mussels, etc., the above harmful organisms will compete for nutrients, deteriorate the water quality, and kill shrimp and shellfish, etc., therefore, the amount of water change needs to be controlled, the seawater to be changed needs to be disinfected and sterilized in advance, and blue-green algae inhibitors, etc. need to be timely fished and splashed.

10. The method of claim 1, wherein, The culture and harvest in sequence in step f are preferably performed, and the middle layer of the culture and the bottom layer of the bottom type of the shellfish are harvested 10-15 days after the upper layer of the planktonic shrimp is harvested, so that the residual bait, small particles and microorganisms can be better utilized by the filter-feeding shellfish, so as to achieve the purposes of efficient utilization of nutrients, green culture and tail water discharge standard.

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