A low-carbon culture method for promoting the growth of nereis virens, selenium enrichment, nutrition and soil methane oxidation capacity

Abstract

The application discloses a low-carbon culture method for promoting growth of Perinereis nuntia, selenium enrichment, nutrition and soil methane oxidation capacity, which comprises the following steps: placing the Perinereis nuntia in soil, adding selenium-rich liquid compost and / or sodium selenite to the soil under certain conditions for culture, and feeding the Perinereis nuntia with rice straw waste. The culture method does not need complicated steps, realizes low-carbon culture, synchronously enhances selenium-rich growth of the Perinereis nuntia, high nutrition and methane oxidation capacity of the culture soil, and provides a new path of "selenium enrichment, growth promotion and carbon reduction" for low-carbon high-value culture of the Perinereis nuntia, and also provides an effective idea for development of high-value low-carbon agricultural technology.

Description

Technical Field

[0001] This invention relates to the field of *Nereis spp.* breeding technology, specifically to a breeding method for *Nereis spp.* that promotes growth and nutrition through selenium enrichment and reduces soil carbon emissions, and more specifically to a method for achieving "selenium enrichment and high nutrition" of *Nereis spp.* and enhancing the methane oxidation capacity of the breeding soil by using selenium-enriched liquid compost and / or sodium selenite. Background Technology

[0002] Warty-snout sandworm [ Tylorrhynchus heterochaetus (Quatrefages, 1866)], commonly known as the rice worm or the mudskipper, belongs to the phylum Annelida of invertebrates ( Annelida Polychaeta ( Polychaeta ), Nereis order ( Eunicida ), Nematoda ( Nereididae The endemic genus is *Nematophorus*. Tylorrhynchus The warty-snout sandworm is an omnivorous benthic animal with a wide diet. It primarily feeds on decaying rice roots, stems, leaves, single-celled algae, and animal and plant debris. It typically inhabits brackish waters in coastal or estuary rice paddies or hides in shallow, silty, and sandy soils. In my country, the warty-snout sandworm is mainly distributed in warm temperate and subtropical regions. Its meat is tender and highly nutritious, with a high protein content, a balanced amino acid profile, and a complete range of crude fat components. It is rich in unsaturated fatty acids and vitamin B, giving it high nutritional and medicinal value. It is also known as "Cordyceps sinensis of the water" and is increasingly regarded as a rare and desirable seafood delicacy, enjoying great popularity in the market.

[0003] In recent years, factors such as the deterioration of the aquatic environment inhabited by the warty sandworm, pesticide pollution in aquaculture, and excessive harvesting have led to a decline in the warty sandworm population, resulting in a continuous decrease in its production and an imbalance between supply and demand. This has caused prices to rise, reaching 80 to 120 yuan per kilogram in the market. In the past, the warty sandworms sold in the market mainly came from wild individuals caught by coastal fishermen. With the continuous increase in market demand, its production is unable to meet market demand, making artificial breeding a promising prospect.

[0004] Selenium (Se) is an essential micronutrient for the growth of humans, animals, and plants. Studies have shown a significant relationship between selenium and various diseases, including Keshan disease, Kashin-Beck disease, cardiovascular disease, and malignant tumors. Adequate selenium intake can effectively alleviate the symptoms of these diseases. However, the global distribution of selenium is highly uneven, and more than 40 countries and regions worldwide face the public health challenge of selenium deficiency. my country is a country with relatively scarce selenium resources, with approximately 51% of its land area classified as selenium-deficient or low-selenium, affecting a population exceeding one billion. Selenium deficiency has become a significant risk factor for endemic cardiomyopathy and tumors, posing a serious threat to national health. Currently, the main ways for humans to obtain selenium include pharmaceutical selenium preparations, dietary intake, and selenium-fortified foods. Among these, supplementation through daily diet has unique advantages such as low cost, high safety, and significant effects, and is considered the most feasible selenium supplementation strategy. Currently, various selenium-enriched biological products, covering animal, plant, and microbial sources, have been successfully prepared using artificial biotransformation technology. Research on selenium-enriched polychaete is still relatively scarce. As a marine benthic annelid, polychaete has biological characteristics such as short growth cycle, high biomass, and strong ability to enrich nutrients, and has the potential value to be developed into a new type of selenium-enriched functional food.

[0005] Against the backdrop of global climate change, the carbon footprint of aquaculture is receiving increasing attention. Climate warming, a global environmental challenge, is primarily driven by the continuous rise in greenhouse gas concentrations. Among numerous greenhouse gases, methane (CH4) emissions are second only to carbon dioxide (CO2), significantly contributing to the intensification of the global greenhouse effect. According to the IPCC Sixth Assessment Report, on a 100-year timescale, methane's global warming potential is approximately 28 times that of carbon dioxide, confirming the crucial importance of controlling methane emissions in curbing global warming. Research indicates a synergistic emission relationship between selenium and greenhouse gases. For example, in black soils of cold regions, soil respiration induces the synergistic emission of greenhouse gases and methylated selenium; by regulating soil selenium form transformation, greenhouse gas production can be indirectly affected.

[0006] Despite some progress in the breeding and related technologies of *Nereiscus spp.*, traditional breeding techniques still face several bottlenecks: First, nutritional fortification techniques are limited, with current breeding methods relying heavily on natural feeds or conventional artificial feeds, lacking targeted micronutrient enrichment technologies, resulting in severe product homogenization. Second, the selenium enrichment mechanism is unclear, selenium-enriched breeding lacks scientific basis, and the amount of selenium added is often arbitrary, making it difficult to achieve the desired enrichment effect. Third, there is a lack of effective means to control greenhouse gas emissions during the breeding process. Currently, there are no systematic research reports on selenium-enriched breeding techniques for *Nereiscus spp.* and their comprehensive impact on growth performance, nutritional quality, and environmental effects. Therefore, there is an urgent need to develop a new ecological breeding technology for *Nereiscus spp.* that integrates selenium enrichment for growth promotion, high nutritional quality improvement, and carbon emission reduction to overcome the aforementioned technical bottlenecks and promote the green and high-quality development of this industry. Summary of the Invention

[0007] The purpose of this invention is to overcome the aforementioned defects and shortcomings in the existing technology and provide a low-carbon breeding method for promoting the growth, selenium enrichment, and nutrition of *Nereis spp.* (a type of silkworm), and enhancing the methane oxidation capacity of the culture soil. This invention is based on the ecological breeding concept of *Nereis spp.*, aiming to improve resource utilization efficiency and effectively reduce the pressure of breeding activities on the ecological environment. Through the use of selenium-enriched liquid compost and sodium selenite in the breeding of *Nereis spp.*, this invention provides a theoretical basis and practical path for improving the selenium-enriched growth of *Nereis spp.* breeding systems.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution: A low-carbon breeding method for promoting the growth, selenium enrichment, nutrition, and enhancing the methane oxidation capacity of the soil for *Nereidum wartyum* involves placing *Nereidum wartyum* in soil supplemented with selenium-enriched liquid compost and / or sodium selenite, and breeding them at 25–30°C for 30–40 days; feeding them 8%–12% rice straw (agricultural waste) every 2–4 days based on their initial body weight, and keeping the soil moist daily; the preparation method of the selenium-enriched liquid compost includes the following steps: S1. The invasive plant Alternanthera philoxeroides and agricultural waste rice straw are washed, dried, and sieved, and then mixed in equal mass ratios to obtain compost material. S2. Feed the starved apple snails with the compost material from step S1 to carry out bioconversion; S3. Add selenium source to the mixed residue of compost material and golden apple snail after bioconversion in step S2 for aerobic composting fermentation. After completion, filter the supernatant, extract the compost residue, and combine the filtrates to obtain selenium-enriched liquid fertilizer.

[0009] This invention involves raising *Nereiscus spp.* in soil, adding selenium-enriched liquid compost and / or sodium selenite under certain conditions, and feeding them with rice straw waste. This method allows for simplified management of *Nereiscus spp.* by promoting selenium-enrichment and growth, simultaneously achieving selenium enrichment, high nutrient levels, and carbon reduction. This invention provides a new pathway for *Nereiscus spp.* farming: selenium enrichment, growth promotion, and carbon reduction. The selenium-enriched liquid fertilizer is obtained by first pre-treating the *Pomacea canaliculata* (golden apple snail) biotransformation to break down the lignin-cellulose complex structure; then, the pre-treated compost material is mixed with the *Pomacea canaliculata* residue, and a selenium source is added for aerobic composting fermentation.

[0010] Furthermore, the warty sandworms are temporarily raised for 5-10 days to allow them to fully adapt to the breeding environment.

[0011] Furthermore, the initial weight of the *Nematostella vesicatoria* is 350.00–450.00 mg, and the body length of the *Nematostella vesicatoria* is 30.00–50.00 mm.

[0012] Furthermore, the amount of selenium-enriched liquid compost added is 15–20 mg / kg of aquaculture soil (dw).

[0013] Preferably, the amount of selenium-enriched liquid compost added is 18.24 mg / kg of aquaculture soil (dw).

[0014] Furthermore, the amount of selenium-enriched liquid compost added is 5–15 mg / kg of aquaculture soil (dw), and the amount of sodium selenite added is 15–25 mg / kg of aquaculture soil (dw).

[0015] Preferably, the amount of selenium-enriched liquid compost added is 9.12 mg / kg of aquaculture soil (dw) and the amount of sodium selenite added is 19.98 mg / kg of aquaculture soil (dw).

[0016] Furthermore, the amount of sodium selenite added is 30–50 mg / kg of aquaculture soil (dw).

[0017] Preferably, the sodium selenite added is 39.95 mg / kg of aquaculture soil (dw).

[0018] Furthermore, the bioconversion described in step S2 involves feeding the starved golden apple snails with compost material daily at a temperature of 25–28°C, pH of 7–8, and aeration for 12–14 hours per day for 15–20 days.

[0019] Preferably, the temperature is 25-26°C, the pH is 7-8, and the aeration time is 13-14 hours per day.

[0020] More preferably, the temperature is 25.6℃, the pH is 7.12, and the aeration time is 13.30 h per day. At this temperature, the degradation rate of lignocellulose by the golden apple snails on the compost material reaches its maximum.

[0021] Further, the starvation treatment in step S2 involves placing the golden apple snail in dechlorinated water for 24 hours to starve it.

[0022] Further, the selenium source mentioned in step S3 is a compound of sodium selenite, sodium selenate, and nano-selenium; the amount of sodium selenite added is 684.44 to 912.59 mg / kg of mixed residue, the amount of sodium selenate added is 747.81 to 997.08 mg / kg of mixed residue, and the amount of nano-selenium added is 312.50 to 420.00 mg / kg of mixed residue.

[0023] Preferably, the sodium selenite addition amount is 782.22 mg / kg mixed residue / 10L water, the sodium selenate addition amount is 854.64 mg / kg mixed residue / 10L water, and the nano selenium addition amount is 357.15 mg / kg mixed residue / 10L water.

[0024] Furthermore, the soil in question is paddy soil.

[0025] Furthermore, the soil moisture content is 30–45%, and the pH is 5–8.

[0026] Furthermore, the soil is soil that has passed through a 2 mm aperture sieve.

[0027] In this invention, a breeding structure for implementing any of the above-described breeding methods includes a breeding basin, paddy soil, selenium sources in different forms and proportions, and a suitable indoor temperature. Furthermore, this invention uses paddy soil and selenium sources as the main basic materials to provide a suitable breeding environment for *Nematostella spp.*

[0028] As a preferred implementation method, this invention forms three breeding formulas for *Nereis spp.* by adding selenium sources in different forms and proportions: a selenium-enriched growth-promoting breeding formula (GP), a high-nutrient breeding formula (HN), and a carbon-reducing breeding formula (CR). The method steps for breeding *Nereis spp.* using these breeding formulas are as follows: 1. The specific steps for preparing the selenium-enriched growth-promoting formula (GP) for *Gnaphalium affine* are as follows: S1. Temporarily raise the warty-snout sandworms for 5-10 days to allow them to fully adapt to the rearing environment. Remove any foreign objects such as stones and branches from the paddy soil, air dry it, crush and sieve it, and accurately weigh 3-5 kg ​​of soil (dw) into the rearing container. Add deionized water to adjust the soil moisture content to 30%-50% (w / v), maintaining a humidity of 30-45% every 2 days with deionized water. Simultaneously, maintain a suitable pH of 5-8, thoroughly mix, and allow the soil to age for 10-15 days. The sieve used should have a 2 mm aperture.

[0029] S2. After the soil treatment in step S1 is completed, add selenium-enriched liquid compost, while the control (CK) does not add selenium source.

[0030] S3. Based on body weight, 20-40 healthy *Nematostella spp.* (those with no disease, no injury, intact body segments, and rapid response) pretreated in step S1 are placed in paddy soil covered with 10 cm of paddy soil and reared at room temperature (25-30℃) for 30-40 days. Every 3 days, they are fed 10% of their initial body weight in rice straw (a type of agricultural waste), and the soil is kept moist daily. The *Nematostella spp.* should have a body weight of 350.00-450.00 mg and a body length of 30.00-50.00 mm.

[0031] Furthermore, the selenium sources in different forms and proportions mentioned in step S2 are selenium-enriched liquid compost and nano-selenium, with an addition amount of 15–20 mg / kg of breeding soil (dw). The resulting *Nereis spp.* breeding formula obtained by this method is a selenium-enriched growth-promoting formula (Se–GP), which can effectively increase the body weight and weight gain of *Nereis spp.*, simultaneously enhance the survival rate to ensure the biomass stability of *Nereis spp.*, and significantly increase the proportion of organic selenium and the selenium enrichment coefficient in the insect body, promoting the bioconversion and accumulation of inorganic selenium to organic selenium, thereby enhancing the product's food safety, nutritional functionality, and the development value of selenium-enriched feed organisms.

[0032] Preferably, the amount of selenium-enriched liquid compost added is 18.24 mg / kg of aquaculture soil (dw).

[0033] 2. The specific steps for preparing the high-nutrition (HN) breeding formula for *Nematostella spp.* are as follows: S1. The *Nereidum wartyum* (a type of silkworm) should first be temporarily raised for 5-10 days to allow it to fully adapt to the rearing environment. Remove any foreign objects such as stones and branches from the paddy soil, air-dry it, crush it, and sieve it. Accurately weigh 3-5 kg ​​of soil (dw) into the rearing container, add deionized water, and adjust the soil moisture content to 30%-50% (w / v). Maintain the humidity at 30-45% every 2 days using deionized water. Simultaneously, maintain a suitable pH of 5-8, thoroughly mix the soil, and allow it to age for 10-15 days. The sieve used should have a 2 mm aperture.

[0034] S2. After the soil treatment in step S1 is completed, selenium sources in different forms and proportions are added, while no selenium source is added to the control (CK). The selenium sources are selenium-enriched liquid compost and sodium selenite.

[0035] S3. Based on body weight, 20-40 healthy *Nematostella spp.* (those with no disease, no injury, intact body segments, and rapid response) pretreated in step S1 are placed in rice paddy soil covered with 10cm of paddy soil and reared at room temperature (25-30℃) for 30-40 days. Every 3 days, they are fed 10% rice straw (a type of agricultural waste) based on their initial body weight, and the soil is kept moist daily. The *Nematostella spp.* should have a body weight of 350.00-450.00 mg and a body length of 30.00-50.00 mm.

[0036] Furthermore, the selenium source mentioned in step S2 is a compound of selenium-enriched liquid compost and sodium selenite, wherein the amount of selenium-enriched liquid compost added is 5-15 mg / kg of culture soil (dw), and the amount of sodium selenite added is 15-25 mg / kg of culture soil (dw). The resulting *Nereis spp.* culture formula is a high-nutrition (HN) formula, which can effectively regulate the crude fat, protein, and ash content or ratio of *Nereis spp.* to improve nutritional quality, simultaneously optimize the amino acid composition and balance to improve protein bioavailability, and improve fatty acid types to enhance lipid nutritional value, thereby comprehensively improving the nutritional quality of the insect and meeting the development needs of high-quality aquatic products and functional foods.

[0037] Preferably, the amount of selenium-enriched liquid compost added is 9.12 mg / kg of aquaculture soil (dw), and the amount of sodium selenite added is 19.98 mg / kg of aquaculture soil (dw).

[0038] 3. The specific steps for the carbon reduction formulation (CR) of *Nematostella spp.* are as follows: S1. The *Nereidum wartyum* (a type of silkworm) should first be temporarily raised for 5-10 days to allow it to fully adapt to the rearing environment. Remove any foreign objects such as stones and branches from the paddy soil, air-dry it, crush it, and sieve it. Accurately weigh 3-5 kg ​​of soil (dw) into the rearing container, add deionized water, and adjust the soil moisture content to 30%-50% (w / v). Maintain the humidity at 30-45% every 2 days using deionized water. Simultaneously, maintain a suitable pH of 5-8, thoroughly mix the soil, and allow it to age for 10-15 days. The sieve used should have a 2 mm aperture.

[0039] S2. After the soil treatment in step S1 is completed, add selenium sources in different forms and proportions, while the control (CK) does not add selenium sources.

[0040] S3. Based on body weight, 20-40 healthy *Nematostella spp.* (those with no disease, no injury, intact body segments, and rapid response) pretreated in step S1 are placed in rice paddy soil covered with 10cm of paddy soil and reared at room temperature (25-30℃) for 30-40 days. Every 3 days, they are fed 10% rice straw (a type of agricultural waste) based on their initial body weight, and the soil is kept moist daily. The *Nematostella spp.* should have a body weight of 350.00-450.00 mg and a body length of 30.00-50.00 mm.

[0041] Furthermore, the selenium source mentioned in step S3 is sodium selenite, and its addition amount is 30-50 mg / kg of aquaculture soil (dw). The resulting *Nereis spp.* aquaculture formula is a carbon reduction (CR) type, which can effectively reduce the methane oxidation potential of the aquaculture soil, promote the metabolic transformation of methane by functional microorganisms, reduce the intensity of greenhouse gas production, enhance the carbon sequestration function and greenhouse gas emission reduction capacity of the aquaculture system, and promote the sustainable development of low-carbon, high-efficiency ecological aquaculture models.

[0042] Preferably, the sodium selenite addition amount is 39.95 mg / kg aquaculture soil (dw).

[0043] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for raising *Nereis spp.* using selenium-enriched growth, high nutrition, and carbon reduction. It innovatively regulates *Nereis spp.* by adding different forms of selenium sources to the breeding substrate in specific proportions, evaluating their growth performance, nutritional quality, and ecological effects. The resulting *Nereis spp.* achieves the following technical effects: (1) significantly increased selenium content in the insect body, meeting the standards for selenium-enriched agricultural products; (2) significantly accelerated growth and development rate; (3) improved protein nutritional value, optimizing the composition and ratio of amino acids and proteins; and (4) significantly reduced greenhouse gas emissions during the breeding process. This invention connects the entire chain of "selenium form regulation—growth and development promotion—nutritional quality improvement—greenhouse gas emission reduction," significantly enhancing the bioavailability and functional targeting of selenium. It achieves the synergistic goals of selenium-enriched growth, high nutritional accumulation, and low-carbon breeding, providing a replicable and scalable technical path for the development of green, high-value aquatic products. This invention breaks through the technical bottleneck in the development of functional polychaete breeding formulas and constructs an integrated technical model of "selenium enrichment, growth promotion, and carbon reduction". It not only realizes the efficient utilization and value enhancement of the trace element selenium in polychaete breeding, but also simultaneously improves the weight gain efficiency of the insects, optimizes the nutritional composition structure, and reduces the carbon footprint of the breeding system. It has significant economic and ecological benefits and has good prospects for industrial application. Attached Figure Description

[0044] Figure 1The effect of a selenium-enriched growth-promoting formula on the body weight of *Nematostella spp.* P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0045] Figure 2 The effect of a selenium-enriched growth-promoting formula on the weight gain rate of *Nematostella spp.* P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0046] Figure 3 The effect of a selenium-enriched growth-promoting formulation on the specific growth rate of *Nematostella spp.* (* indicates...) P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0047] Figure 4 The effect of a selenium-enriched growth-promoting formula on the body length of *Nematocystis wartyridis*. *Indicates the effect of... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0048] Figure 5 The effect of a selenium-enriched growth-promoting formula on the body length growth rate of *Nematocystis wartyridis*. *Indicates the effect of... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0049] Figure 6 The effect of a selenium-enriched growth-promoting formulation on the specific growth rate of the body length of *Nematocystis wartyridis*. *Indicates the effect of... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0050] Figure 7 The effect of a selenium-enriched growth-promoting formulation on the survival rate of *Nematostella spp.* P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. PA difference of ≤0.01 is significant.

[0051] Figure 8 The effect of a selenium-enriched growth-promoting formula on the total selenium, organic selenium, and inorganic selenium content of *Nereidum wartyum*. *Indicates in P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0052] Figure 9 The effect of a selenium-enriched growth-promoting formula on the ratio of organic to inorganic selenium in *Nereidum wartyum*. *Indicates the effect of... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0053] Figure 10 The effect of a selenium-enriched growth-promoting formulation on the selenium enrichment coefficient of *Nereidum wartyum*. *Indicates... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0054] Figure 11 The effect of a high-nutrient formulation on the crude protein content of *Nematostella spp.* P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P ≤0.01 indicates a significant difference Figure 12 The effect of a highly nutritious formula on the ash content of *Nematostella spp.* P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P ≤0.01 indicates a significant difference Figure 13 The effect of a high-nutrient formulation on the crude fat content of *Nematostella spp.* P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0055] Figure 14 The effect of carbon-reducing formulations on the methane oxidation potential of soil used for Nematoda farming. * indicates that... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference.P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant.

[0056] Figure 15 The effect of a carbon-reducing formulation on total methane oxidation in soil used for *Nematocera wartyrifolia* farming. * indicates... P ≤0.05 indicates a significant difference; ** represents a statistically significant difference. P ≤0.01 indicates a significant difference; *** represents a statistically significant difference. P A difference of ≤0.01 is significant. Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0061] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0062] Example 1: Effect of selenium-enriched growth-promoting formula on body weight gain of *Nematocystis wartyri* 1. Preparation of selenium-enriched growth-promoting liquid compost (selenium-enriched growth-promoting formula) (1) Remove the invasive plant Alternanthera philoxeroides and agricultural waste rice straw from the sand, gravel and weeds, dry them separately, crush them and sieve them for later use; the drying temperature is 60℃ and they are passed through a 20-mesh standard sieve; (2) Mix the invasive plant Hollow Lotus and rice straw treated in step (1) at a mass ratio (dry weight) of 1:1 to obtain compost material; place 14 golden apple snails of equal weight and size that have been starved (placed in dechlorinated water for 24 hours) in a compost container containing 10L of water and feed them compost material for bioconversion; the bioconversion temperature is 25.6℃, pH=7.12, the aeration time is 13.30 h / day, and the bioconversion is carried out for 15 days, with a total of 70 g of compost material fed each day; the golden apple snail weighs 20-30 g, has a snail width of 4-5 cm, and a snail height of 4.5-5.5 cm.

[0063] S3. The biotransformed material (mixed residue of compost and golden apple snail) from step (2) is aerobically composted for 21 days with the addition of a selenium source. Aeration is stopped for 5-10 minutes every 2-3 days, and the mixture is stirred 1-2 times. After completion, the supernatant is centrifuged and filtered, and the compost residue is repeatedly extracted three times to obtain selenium-enriched liquid compost. The selenium source is sodium selenite, sodium selenate, and nano-selenium. The sodium selenite addition amount is 782.22 mg / kg mixed residue / 10L water, the sodium selenate addition amount is 854.64 mg / kg mixed residue / 10L water, and the nano-selenium addition amount is 357.15 mg / kg mixed residue / 10L water. The centrifugation temperature is 4℃, the relative centrifugal force is 8000 g, and the centrifugation time is 10 min.

[0064] 2. Breeding methods for selenium-enriched warty-lipped sandworms (1) The warty-snout sandworms were temporarily raised for 7 days to allow them to fully adapt to the breeding environment. The paddy soil was cleaned of stones, branches, and other foreign objects, air-dried, crushed, and sieved. 4 kg of soil (dw) was accurately weighed into the breeding basin, and deionized water was added to adjust the soil moisture content to 45% (w / v). The soil was kept at 30-45% humidity every 2 days using deionized water. Simultaneously, the pH was adjusted appropriately to 7 degrees. After thorough mixing, the soil was allowed to age for 14 days. The sieve used had a 2 mm aperture.

[0065] (2) After the soil treatment in step (1) is completed, apply the selenium-enriched growth-promoting formula, while the control (CK) does not add selenium source. The amount of the selenium-enriched growth-promoting formula added is 15-20 mg / kg of aquaculture soil (dw). Specifically, the amount of selenium-enriched liquid compost added is 18.24 mg / kg of aquaculture soil (dw).

[0066] (3) Based on weight and uniformity, 20 healthy *Nematostella spp.* (insects without disease or injury, with intact body segments, and exhibiting rapid response) were placed in rice paddy soil covered with 10 cm of paddy soil and cultured at room temperature of 26±1℃ for 30 days. Every 3 days, the *Nematostella spp.* were fed 10% rice straw (agricultural waste) based on their initial weight, and the soil was kept moist daily. The *Nematostella spp.* had a weight of 350.00–450.00 mg and a body length of 30.00–50.00 mm.

[0067] (4) When measuring the weight of *Nematostella spp.*, the insects were washed with purified water, and the surface moisture was gently wiped with sterile paper before being measured using a 0.0001 g balance. The weight growth rate and specific weight growth rate of *Nematostella spp.* are calculated as shown in formulas (1) and (2):

[0068] In the formula, Initial body mass (mg); Final body mass (mg).

[0069]

[0070] In the formula, Initial body mass (mg); For growth D Body weight (mg) at the time of day; D The breeding time is d.

[0071] (5) Changes in overall weight, weight growth rate, and specific weight growth rate of *Nematocystis wartyta* are as follows: Figure 1 , Figure 2 and Figure 3 As shown. When *Nereidum wartyum* was cultured using the prepared selenium-enriched liquid fertilizer, the total weight of *Nereidum wartyum* treated with the selenium-enriched growth-promoting formula increased by 165.0% compared to the control (CK). P <0.05)( Figure 1 Compared with the control group (CK), the weight gain rate of the selenium-enriched growth-promoting formula treatment increased by 161.3%. P <0.05)( Figure 2 Compared to the control (CK), the selenium-enriched growth-promoting formula treatment resulted in a 120.9% increase in body weight-specific growth rate. P <0.05)( Figure 3 Compared to the control (CK), the selenium-enriched growth-promoting formula promoted the body weight, body weight growth rate, and body weight-specific growth rate of the warty spider silkworm.

[0072] Example 2: Effect of selenium-enriched growth-promoting formula on body length growth of *Nematocystis wartyri* The selenium-enriched liquid compost prepared in Example 1 was used. The steps (1) to (3) of the breeding method of selenium-enriched warty sandworm were the same as in Example 1.

[0073] (4) The body length of the warty-snout sandworm was measured using a micrometer (accurate to 0.0001 cm), with the standard length measured from the head to the tail end. The calculation of the body length growth rate and the specific growth rate of body length were based on formulas (3) and (4).

[0074]

[0075] In the formula, Initial body length (mm); The final body length is (mm).

[0076]

[0077] In the formula, Initial body length (mm); For growth DThe body length of the sky (mm); D The breeding time is d.

[0078] (5) The changes in overall length, body length growth rate, and specific body length growth rate of the *Nematocystis wartyta* are as follows: Figure 4 , Figure 5 and Figure 6 As shown. After 30 days of the breeding experiment, the average body length of individuals in both the control group (CK, without selenium source) and the selenium-enriched growth-promoting formula treatment showed a significant increase compared to the initial state. P <0.05). With regard to Se treatment, the average body length increased from the initial 44.18 mm to 71.05 mm, an increase of 24.4% ( P <0.05); while the body length of CK increased from 42.63 mm to 53.00 mm, an increase of 60.8% ( P <0.05)( Figure 4 Meanwhile, compared with the control (CK), the body length growth rate of the selenium-enriched growth-promoting formula treatment increased by 149.9% (…). P <0.05)( Figure 5 Furthermore, the specific growth rate of body length in both the selenium-enriched growth-promoting formulation treatment and the control group (CK) was significantly higher than the initial value. P <0.05%. Among them, the specific growth rate of body length in the control (CK) was 0.73%, while the selenium-enriched growth-promoting formula treatment increased it by 54.1% compared to the control (CK). P <0.05)( Figure 6 Selenium-enriched growth-promoting formula treatment has a significant promoting effect on the body length growth of *Nematostella spp.*, and can effectively increase its growth rate.

[0079] Example 3: Effect of selenium-enriched growth-promoting formula on the survival rate of *Nematocystis wartyri* The selenium-enriched growth-promoting formula prepared in Example 1 was used, and the steps (1) to (3) of the breeding method of selenium-enriched warty-snout sandworm were the same as in Example 1.

[0080] (4) On the 30th day of the experiment, samples were taken and the number of *Nematocystis wartyri* tails in each basin was recorded. The survival rate of *Nematocystis wartyri* was calculated using the formula (5):

[0081] In the formula, The initial quantity (tail); This represents the final number (tails).

[0082] (5) The survival rate of the warty-snout sandworm is as follows Figure 7As shown. After a 30-day rearing experiment of *Nematostella spp.*, the survival rate of the selenium-enriched growth-promoting formula treatment reached 98.75%. Compared with the control (CK, no selenium source added), the survival rate of the selenium-enriched growth-promoting formula treatment increased by 5.1% (…). P <0.05), the selenium-enriched growth-promoting formula effectively improves the survival performance of *Nematocera wartyri* in aquaculture and reduces its mortality risk. Selenium may play an important nutritional regulatory role in enhancing the stress resistance or physiological adaptability of *Nematocera wartyri*.

[0083] Example 4: Effects of selenium-enriched growth-promoting formulation on the total selenium, organic selenium, and inorganic selenium content of *Nereidum wartyum*. The selenium-enriched liquid compost prepared in Example 1 was used. The steps (1) to (3) of the breeding method of selenium-enriched warty sandworm were the same as in Example 1.

[0084] (4) Selenium is one of the important trace elements in organisms and has a variety of biological functions. After cleaning the intestines of each group of *Nereidium wartyum* in glass culture dishes for 12 hours, they were washed, rinsed three times with distilled water, dried, and then freeze-dried in liquid nitrogen. The *Nereidium wartyum* samples were then freeze-dried in a freeze dryer for 48 hours. After drying, the *Nereidium wartyum* samples were ground using a high-throughput tissue homogenizer and passed through a 50-mesh sieve. They were then stored in sealed bags and dried for later use. The total selenium content of *Nereidium wartyum*, inorganic selenium, and total selenium content of the soil were determined by atomic fluorescence spectrometry (AFS). The organic selenium content of *Nereidium wartyum* was calculated according to formula (6).

[0085]

[0086] (5) The total selenium, organic selenium, and inorganic selenium content of *Nematocystis wartyri* are as follows: Figure 8 As shown, after 30 days of rearing, there were significant differences in both organic and inorganic selenium content between the control group (CK, without selenium source) and the selenium-enriched growth-promoting formula treatment (with selenium source). Specifically, the total selenium content in the selenium-enriched growth-promoting formula treatment was 61.99 times that of the CK. P <0.05)( Figure 8 I). After 30 days, the trend of organic selenium content change under the selenium-enriched growth-promoting formula treatment was basically consistent with that of total selenium content, showing a pattern of selenium-enriched growth-promoting formula treatment > CK (control). Figure 8 II), among which, compared with CK, the organic selenium content of the selenium-enriched growth-promoting formula treatment was 97.88 times that of the selenium-free CK, significantly increasing the organic selenium content in the sandworm (II). P <0.05%. The inorganic selenium content in *Nematocystis wartyri* showed significant differences under different selenium treatment conditions ( Figure 8 III). Treatment with a selenium-enriched growth-promoting formula increased the accumulation of inorganic selenium in *Nematocystis wartyta*, with a content 13.05 times that of the control group (CK). P <0.05).

[0087] (6) The ratio of organic to inorganic selenium in *Nematocystis wartyri* is as follows: Figure 9 As shown, at 30 days, the proportion of organic selenium in the *Nematostella spp.* treated with the selenium-enriched growth-promoting formula was significantly higher than 90%, exceeding 90% of the total selenium content. In contrast, the selenium-free control (CK) had an organic selenium content of 57.9%, significantly lower than the selenium-enriched formula. The proportion of inorganic selenium in the total selenium content showed the opposite trend after treatment with the selenium-enriched formula, with the inorganic selenium content in the CK > Se treatment. Compared to the CK, the proportion of inorganic selenium in the selenium-enriched growth-promoting formula decreased by 78.9% (…). P <0.05). The selenium-enriched growth-promoting formula helps promote the conversion of inorganic selenium into organic selenium by the warty spider silkworm.

[0088] Example 5: Effect of selenium-enriched growth-promoting formulation on the selenium enrichment coefficient of *Nereidum wartyum*. Using the selenium-enriched growth-promoting formula prepared in Example 1, the steps (1) to (3) of the breeding method of selenium-enriched warty sandworm are the same as in Example 4.

[0089] (4) The total selenium content of the soil used for the rearing of *Nereidum wartyum* was determined by atomic fluorescence spectrometry (AFS). The selenium bioaccumulation coefficient of *Nereidum wartyum* was also determined. The calculation formula is shown in formula (7):

[0090] (6) The selenium bioaccumulation coefficient of *Nereidum wartyum* is as follows: Figure 10 As shown, after 30 days of rearing, the selenium bioaccumulation coefficient of *Nematocera wartyri* treated with Se reached 0.98, while the selenium bioaccumulation coefficient of the control (CK) was 0.39. Compared with the CK, the selenium-enriched growth-promoting treatment increased the selenium bioaccumulation coefficient by 150.2%. P <0.05), which indicates that *Nematostella parasitica* has a good enrichment capacity for Se.

[0091] Example 6: Effect of a high-nutrition formula on the amino acid content of *Nematostella wartyri* Using the selenium-enriched liquid compost prepared in Example 1, a high-nutrient formula was formulated, and the breeding method for *Nematostella ectenes* is as follows: (1) The warty-snout sandworms were temporarily raised for 7 days to allow them to fully adapt to the breeding environment. The paddy soil was cleaned of stones, branches, and other foreign objects, air-dried, crushed, and sieved. 4 kg of soil (dw) was accurately weighed into the breeding basin, and deionized water was added to adjust the soil moisture content to 45% (w / v). The soil was kept at 30-45% humidity every 2 days using deionized water. Simultaneously, the pH was adjusted appropriately to 7 degrees. After thorough mixing, the soil was allowed to age for 14 days. The sieve used had a 2 mm aperture.

[0092] (2) After the soil treatment in step (1) is completed, a high-nutrient formula is applied to the control (CK) soil, which does not contain any selenium source. The selenium source in the high-nutrient formula is a mixture of selenium-enriched liquid compost and sodium selenite. The amount of selenium-enriched liquid compost added is 5–15 mg / kg of aquaculture soil (dw), and the amount of sodium selenite added is 15–25 mg / kg of aquaculture soil (dw). The amount of selenium-enriched liquid compost added is 9.12 mg / kg of aquaculture soil (dw), and the amount of sodium selenite added is 19.98 mg / kg of aquaculture soil (dw).

[0093] (3) Based on weight and uniformity, 20 healthy *Nematostella spp.* (insects without disease or injury, with intact body segments, and exhibiting rapid response) were placed in rice paddy soil covered with 10 cm of paddy soil and cultured at room temperature of 26±1℃ for 30 days. Every 3 days, the *Nematostella spp.* were fed 10% rice straw (agricultural waste) based on their initial weight, and the soil was kept moist daily. The *Nematostella spp.* had a weight of 350.00–450.00 mg and a body length of 30.00–50.00 mm.

[0094] (4) Amino acids are the basic structural units that make up proteins. They are divided into essential amino acids and non-essential amino acids, and their composition ratio determines the nutritional quality and palatability of proteins. This invention uses high-performance liquid chromatography-mass spectrometry (HPLC-MS) to determine the composition and content of amino acids, as shown in Table 1, in accordance with national standard GB / T5009.124~2016. Table 1. Effects of high-nutrition formulation on amino acid composition and content of *Nematostella spp.*

[0095] Note: CK – No selenium source added; Formula treatment – ​​High-nutrient formula, Se treatment. * represents essential amino acids; ** represents semi-essential amino acids; # represents non-essential amino acids; ^ represents flavor amino acids; Different lowercase letters in the same row indicate significant differences between the post-culture treatment and the control. P <0.05. Data are mean ± standard error, n=4.

[0096] (5) After 30 days, a total of 17 amino acids were found in the selenium treatment (Table 1), including 7 essential amino acids (EAA), 1 semi-essential amino acid (CEAA), 9 non-essential amino acids (NEAA) and 4 flavor amino acids (FAA), and the total amino acid (TAA) was at a high level (>60.00 g / kg).

[0097] The highest content of glutamic acid (Glu) was observed, ranging from 9.29 g / kg to 11.49 g / kg. Compared with the control (CK), the content of glutamic acid in the high-nutrient formula treatment increased by 23.63%. P<0.05); followed by aspartic acid (#^Asp) (7.00 g / kg~8.14 g / kg) and leucine (*Leu) (4.90 g / kg~5.60 g / kg), both with relatively high contents (>4.90 g / kg). After selenium treatment, except for methionine (*Met), tyrosine (#Tyr), cysteine ​​(#Cys), and proline (#Pro), the contents of other amino acids were higher than those in the selenium-free CK (<0.05); P <0.05%. The content of proline (#Pro) in Se-treated cells was 14.1% higher than that in control cells (CK). P <0.05).

[0098] The total amino acid (TAA) of each treatment showed that the high-nutrient formula treatment was greater than the control (CK), and the high-nutrient formula treatment significantly increased by 26.11% compared with the selenium-free CK. P <0.05). The total content of essential amino acids (EAA) showed that the high-nutrient formula treatment > CK, and the high-nutrient formula treatment was 1.31 times that of the selenium-free CK. The high-nutrient formula treatment had the best effect.

[0099] The content of non-essential amino acids (NEAAs) was shown to be higher in the high-nutrient formula treatment for selenium-free CK ( P <0.05). The content of flavor amino acids (FAA) showed that the Se treatment > CK. The amino acid composition ratio of *Nematocystis wartyri* differed under high-nutrition formulation treatments. The proportion of essential amino acids in total amino acids showed that the Se treatment > selenium-free CK (43.5%). The trend of the proportion of non-essential amino acids (NEAA / TAA) was opposite to that of EAA / TAA, with CK > Se treatment. The EAA / NEAA ratio showed that the high-nutrition formulation treatment > selenium-free CK. The proportion of flavor amino acids (FAA / TAA) ranged from 31.75% to 34.25%, with the high-nutrition formulation treatment consistently higher than the selenium-free CK.

[0100] Example 7: Effect of a high-nutrient formulation on the fatty acid content of *Nematostella wartyri* Using the selenium-rich liquid compost prepared in Example 1, a high-nutrition formula was prepared, and the steps (1) to (3) of the breeding method of *Syngonium glomeratum* were the same as in Example 6.

[0101] (4) Fatty acids refer to the mixture of long-chain carboxylic acids obtained after the hydrolysis of crude fat, including SFA, MUFA, and PUFA. The content of EPA and DHA determines its feed value. This invention uses gas chromatography-mass spectrometry (GC-MS) to determine the types and contents of fatty acids, referring to national standards GB5009.168-2016. See Table 2 for details. Table 2. Effects of high-nutrition formulation on fatty acid composition and content of *Nephroptiformis wartyri*.

[0102] Note: CK – No selenium source added; Formula treatment – ​​High-nutrient formula. * represents essential amino acids; ** represents semi-essential amino acids; # represents non-essential amino acids; ^ represents flavor amino acids; Different lowercase letters in the same row indicate significant differences between the post-culture treatment and the control. P <0.05. Data are mean ± standard error, n=4.

[0103] (5) The high-nutrient formulation treatment significantly increased the fatty acid content in *Nematocystis wartyta* (Table 2). Eighteen fatty acids were detected in *Nematocystis wartyta* treated with the high-nutrient formulation, including seven saturated fatty acids (SFA), four monounsaturated fatty acids (MUFA), and seven polyunsaturated fatty acids (PUFA). Seventeen fatty acids were detected without selenium (CK). Compared with the selenium-free CK, the high-nutrient formulation treatment additionally detected C20:1 monounsaturated fatty acids.

[0104] The total saturated fatty acid (SFA) content differed significantly between the high-nutrient formulation treatment and the selenium-free control. P <0.05%, high-nutrient formula treatment > CK ( P <0.05). C16:0 and C18:0 were the main fatty acid types, accounting for 51.6% and 41.7% respectively in the high-nutrient formulation treatment. Compared with the control (CK), the C16:0 and C18:0 fatty acid content increased by 408.9% and 460.5% respectively in the high-nutrient formulation treatment. P <0.05%, the high-nutrient formula treatment increased by 14.0% ( P <0.05).

[0105] Monounsaturated fatty acid (MUFA) content showed a pattern of high-nutrient formulation > selenium-free CK ( P <0.05). Among them, C18:1n9c is the main fatty acid, accounting for 80.46% of the content in the high-nutrition formula treatment, which is 13.70 times that of the selenium-free CK.

[0106] The content of polyunsaturated fatty acids (PUFAs) showed that the high-nutrient formulation treatment was higher than the control (CK). C18:2n6c was the main fatty acid, accounting for 40.8% of the total PUFAs in the high-nutrient formulation treatment, which was 436.1% higher than the selenium-free control. P <0.05).

[0107] Among the n-3 series fatty acids, the high-nutrient formulation showed the highest treatment level (0.08 g / kg), higher than the selenium-free control (CK). P <0.05. The high-nutrient formula treatment had the highest content of n-6 series fatty acids (2.71 g / kg), which was also higher than that of the selenium-free CK (control group).P <0.05). The high-nutrient formulation treatment was 3.11 times that of the selenium-free control (CK). Regarding the n-3 / n-6 ratio, the selenium-free CK had a higher ratio than the high-nutrient formulation treatment ( P <0.05).

[0108] Example 8: Effect of a high-nutrition formulation on the crude protein content of *Nematostella wartyri* Using the selenium-rich liquid compost prepared in Example 1, a high-nutrition formula was prepared, and the steps (1) to (3) of the breeding method of *Syngonium glomeratum* were the same as in Example 6.

[0109] (4) Crude protein reflects the potential quality of the insect as a protein source. The crude protein content of *Nematostella spp.* was measured according to the national standard GB5009.5~2016. The crude protein content of *Nematostella spp.* is as follows: Figure 11 As shown, after 30 days of cultivation, there was a significant difference in crude protein content between the high-nutrient formula treatment and the control group of *Nematostella spp.* The crude protein content in the high-nutrient formula treatment was significantly increased by 26.9% compared to the control group. P <0.05). The highly nutritious formula significantly promotes the accumulation of protein in the *Nematocystis wartyri*, with Se treatment showing the most significant effect.

[0110] Example 9: Effect of a high-nutrition formulation on the ash content of *Nematostella wartyri* Using the selenium-rich liquid compost prepared in Example 1, a high-nutrition formula was prepared, and the steps (1) to (3) of the breeding method of *Syngonium glomeratum* were the same as in Example 6.

[0111] (4) Ash content refers to the inorganic substances remaining after food is burned. The ash content of the nutritional components of *Nematostella spp.* was measured according to the national standard GB5009.4~2016. The ash content value was calculated by differential gravimetric method after burning. The specific steps are as follows: freeze-dried *Nematostella spp.* was passed through a 50-mesh sieve, and the constant weight of the sample was weighed and recorded. (g), then the crucible containing the sample was placed in a muffle furnace and heated at 600℃ for 2 h. After cooling to room temperature, it was removed, weighed, and recorded. ,g), and calculate the ash content according to formula (7):

[0112] (5) Ash content of *Nematostella vesicatoria* as follows Figure 12 As shown, at the end of the 30-day rearing experiment, there was a significant difference in ash content between the two groups of *Nematostella spp.* The ash content of the high-nutrition formula treatment was 0.62%, while the ash content of the control group (CK) was 2.45%. Compared to the CK, the ash content of the high-nutrition formula treatment was reduced by 74.5%. P<0.05), which indicates that the high-nutrient formula significantly reduced the deposition of inorganic matter in the body of *Nereidia wartyta*, or that the high-nutrient formula may have improved the nutritional quality of *Nereidia wartyta* by optimizing mineral metabolism or promoting organic matter synthesis, increasing biomass, reducing the relative proportion of ash in dry matter.

[0113] Example 10: Effect of a high-nutrient formulation on the crude fat content of *Nematostella wartyri* Using the selenium-rich liquid compost prepared in Example 1, a high-nutrition formula was prepared, and the steps (1) to (3) of the breeding method of *Syngonium glomeratum* were the same as in Example 6.

[0114] (5) Crude fat refers to the total amount of lipids soluble in ether in the body of *Nematocystis wartyta*, which is the main carrier of energy reserves and fat-soluble vitamins. The crude fat content of the nutritional components of *Nematocystis wartyta* was determined in accordance with the national standard GB5009.6~2016.

[0115] (6) Crude fat content of *Pteris vittata* is as follows: Figure 13 As shown, after 30 days of rearing, the crude fat content of *Nereidum wartyum* in the high-nutrient formula and the control (CK, without selenium) was 2.62% and 1.39%, respectively. Compared with the CK, the crude fat content in the high-nutrient formula treatment increased significantly by 88.7%, indicating that the high-nutrient formula significantly promoted the synthesis and accumulation of fat in *Nereidum wartyum*, revealing that selenium may enhance the energy reserve capacity of the insect by regulating the activity of lipid metabolism-related enzymes or optimizing energy distribution patterns.

[0116] Example 11: Effect of carbon-reducing formulation on the methane oxidation potential of soil used for Nematodes rubrum farming (1) The warty-snout sandworms were temporarily raised for 7 days to allow them to fully adapt to the breeding environment. The paddy soil was cleaned of stones, branches, and other foreign objects, air-dried, crushed, and sieved. 4 kg of soil (dw) was accurately weighed into a breeding basin, and deionized water was added to adjust the soil moisture content to 45% (w / v). The soil was kept at 30-45% humidity every 2 days using deionized water. Simultaneously, the pH was adjusted appropriately to 7 degrees. After thorough mixing, the soil was allowed to age for 14 days. The sieve used had a 2 mm aperture.

[0117] (2) After the soil treatment in step (1) is completed, a carbon reduction formula is set up for treatment, and the control (CK) does not add selenium source. The carbon reduction formula uses sodium selenite, and its addition amount is 30-50 mg / kg aquaculture soil (dw). Specifically, the sodium selenite addition amount is 39.95 mg / kg aquaculture soil (dw).

[0118] (3) Based on their weight and uniformity, 20 healthy *Nematostella spp.* (insects without disease or injury, with intact body segments, and exhibiting rapid response) were placed in rice paddy soil covered with 10 cm of paddy soil and cultured at room temperature of 26±1℃ for 30 days. Every 3 days, the *Nematostella spp.* were fed 10% rice straw (agricultural waste) based on their initial weight, and the soil was kept moist daily. The *Nematostella spp.* had a weight of 350.00–450.00 mg and a standard weight of 30.00–50.00 mg.

[0119] (4) Soil methane oxidation potential was determined on days 1, 5, 10, 15, 20, 25 and 30. The specific procedure was as follows: 10 g of fresh soil sample was weighed and placed in a 150 mL serum bottle, and 30 mL of methane gas was injected; each treatment was repeated 4 times. The serum bottle was double-sealed with a butyl rubber stopper and a polypropylene cap, and gas samples were collected at 0, 1, 2 and 3 h under light-protected conditions. The methane concentration in the gas samples was determined by gas chromatography (GC-7890A, Agilent Technologies, Inc., California, USA), and the soil methane oxidation potential was calculated according to formula (8).

[0120]

[0121] In the formula, R It is the oxidation rate of methane (μg / g / h); This is the final concentration of methane (μL / L); This is the initial concentration of methane (μL / L); V It is the effective space for the gas in the flask. ); m It is the dry weight of the soil (g); ρ This is the density of methane under standard conditions (0.716 g / L). t It is the duration (h).

[0122] (4) Soil methane oxidation potential refers to the maximum capacity of a unit mass of soil to oxidize methane per unit time under suitable temperature and humidity conditions. It is a key indicator characterizing the activity of soil methane-oxidizing microorganisms and the atmospheric methane sink function. The dynamic changes in soil methane oxidation rate are as follows: Figure 14As shown, during the entire aquaculture period, the soil methane oxidation rate in the carbon-reduced formulation treatment showed a trend of first increasing and then decreasing, while the soil methane oxidation rate in the control (CK, without selenium source) remained relatively stable throughout the aquaculture period, ranging from 6.17 μg / g / h to 6.50 μg / g / h. The carbon-reduced formulation treatment had a phased activation effect on soil methane oxidation function. In the early stage (0–15 days), the carbon-reduced formulation treatment may have significantly improved the soil methane oxidation potential by promoting the proliferation of methane-oxidizing bacteria or enhancing the activity of methane monooxygenase, reaching a maximum soil methane oxidation rate of 13.88 μg / g / h on day 15. However, in the later stage (15–30 days), with substrate consumption, accumulation of metabolites, or succession of microbial community structure, this promoting effect gradually diminished, reflecting that the regulatory effect of the carbon-reduced formulation treatment on soil methane oxidation is time-dependent.

[0123] Example 12: Effect of carbon-reducing formulation on total methane oxidation in soil used for *Nematocera wartyrifolia* farming Steps (1) to (3) are the same as in Example 11.

[0124] (4) Total methane oxidation in soil as follows Figure 15 As shown, after 30 days of cultivation, the total methane oxidation in the soil treated with Se reached 78.11 mg, which was 71.47% higher than that of the control (CK) (45.55 mg). P <0.05). The carbon reduction formulation treatment can significantly reduce net methane emissions from the soil, which is presumably achieved by activating the metabolic activity of methane-oxidizing bacteria, thereby enhancing the soil's ability to consume atmospheric methane and reducing the greenhouse gas emission intensity of the aquaculture system.

Claims

1. A low-carbon farming method for promoting the growth, selenium enrichment, nutrition, and soil methane oxidation capacity of *Nematocera wartyri*, characterized in that, To raise *Nereidum wartyum* in soil supplemented with selenium-enriched liquid compost and / or sodium selenite at 25–30°C for 30–40 days, feed them 8%–12% rice straw (agricultural waste) every 2–4 days based on their initial body weight, and keep the soil moist daily; the preparation method of the selenium-enriched liquid compost includes the following steps: S1. The invasive plant Alternanthera philoxeroides and agricultural waste rice straw are washed, dried, and sieved, and then mixed in equal mass ratios to obtain compost material. S2. Feed the starved apple snails with the compost material from step S1 for bioconversion; S3. Add selenium source to the mixed residue of compost material and golden apple snail after bioconversion in step S2 for aerobic composting fermentation. After completion, filter the supernatant, extract the compost residue, and combine the filtrates to obtain selenium-enriched liquid fertilizer.

2. The method according to claim 1, characterized in that, The warty sandworms should be temporarily raised for 5 to 10 days to allow them to fully adapt to the breeding environment.

3. The method according to claim 1, characterized in that, The initial weight of the *Nematostella vesicatoria* was 350.00–450.00 mg, and the body length was 30.00–50.00 mm.

4. The method according to claim 1, characterized in that, The amount of selenium-enriched liquid compost added is 15–20 mg / kg soil.

5. The method according to claim 1, characterized in that, The amount of selenium-enriched liquid compost added is 5–15 mg / kg soil, and the amount of sodium selenite added is 15–25 mg / kg soil.

6. The method according to claim 1, characterized in that, The amount of sodium selenite added is 30–50 mg / kg soil.

7. The method according to claim 1, characterized in that, The biological transformation described in step S2 involves feeding the starved golden apple snails with compost material daily at a temperature of 25–28°C, pH of 7–8, and aeration for 12–14 hours per day for 15–20 days.

8. The method according to claim 1, characterized in that, The selenium source mentioned in step S3 is a compound of sodium selenite, sodium selenate and nano-selenium; the amount of sodium selenite added is 684.44 to 912.59 mg / kg of mixed residue, the amount of sodium selenate added is 747.81 to 997.08 mg / kg of mixed residue, and the amount of nano-selenium added is 312.50 to 420.00 mg / kg of mixed residue.

9. The method according to claim 1, characterized in that, The soil in question is paddy soil.

10. The method according to claim 1, characterized in that, The soil moisture content is 30-45%, and the pH is 5-8.

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