A method for constructing a multi-element complementary largemouth bass comprehensive culture system

Abstract

The application provides a largemouth bass multi-element comprehensive breeding system construction method based on element complementarity, comprising the following steps: screening of comprehensive breeding varieties based on element complementarity; construction of a multi-element comprehensive breeding system; optimization of the stocking ratio of the constructed multi-element comprehensive breeding system; and verification of the efficiency of the largemouth bass multi-element comprehensive breeding system by using an Ecopath model. The application screens the matching varieties for the largemouth bass comprehensive breeding system by using the scientific and quantitative element complementarity principle, and verifies the system energy flow by combining the Ecopath model, so that the nitrogen and phosphorus circulation efficiency of the largemouth bass multi-element comprehensive breeding system is significantly improved, the environmental load is reduced, and the emission reduction and efficiency increase of the breeding system are realized.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, specifically to a method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity. Background Technology

[0002] Largemouth bass, a high-value carnivorous fish, is commonly farmed using a monoculture model with high-protein feed. This results in large amounts of nitrogen (N) and phosphorus (P) being released into the water and sediment as uneaten feed and metabolic waste, causing severe eutrophication. To address this problem, the introduction of fish with different diets for diversified integrated aquaculture has become a research hotspot.

[0003] In existing technologies, common integrated aquaculture models are mostly based on the farmer's past experience and qualitative understanding of feeding habits. For example, in ponds where carnivorous fish (such as largemouth bass) are farmed, filter-feeding fish (such as silver carp and bighead carp) are stocked together to control plankton, or benthic omnivorous fish (such as crucian carp) are stocked together to clean up uneaten feed.

[0004] Existing technologies generally employ a dual-element integrated farming model of "bass-bighead carp" or "bass-crucian carp." The specific operation involves pairing a certain number of bighead carp or crucian carp with the largemouth bass pond. The bighead carp filter-feed on zooplankton and suspended particulate matter, purifying the water; the crucian carp feed on uneaten feed and benthic organisms, cleaning the water and thus improving the survival rate and growth rate of the largemouth bass. However, existing largemouth bass farming models have the following drawbacks:

[0005] 1. Lack of quantitative basis for species selection: The selection of existing integrated aquaculture species (such as silver carp, bighead carp, crucian carp, etc.) relies heavily on experience and lacks scientific quantitative screening indicators based on the complementarity of biochemical element (C:N:P) requirements and aquaculture waste emission characteristics. This results in low nutrient utilization efficiency between the integrated species and the main species and the system fails to achieve optimal niche complementarity.

[0006] 2. Single evaluation dimension: Existing technologies for evaluating integrated aquaculture models often focus on single dimensions such as growth performance and water quality physicochemical indicators, lacking a macro- and systematic evaluation of the overall energy flow, nutrient cycling efficiency, and system stability of the ecosystem.

[0007] 3. Blindness in the optimization of aquaculture models: When determining the three-way or multi-way integrated aquaculture, there is a lack of systematic comparative research on the selection of specific species combinations and stocking ratios, which leads to blindness in the optimization of models. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity. By scientifically and quantitatively selecting compatible species for integrated aquaculture of largemouth bass based on the principle of element complementarity, and by combining the Ecopath model to verify the system's energy flow, the method significantly improves the nitrogen and phosphorus cycle efficiency of the multi-element integrated aquaculture system for largemouth bass, reduces environmental load, and achieves emission reduction and efficiency improvement in the aquaculture system.

[0009] The technical solution of the present invention is as follows:

[0010] A method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity includes the following steps:

[0011] Comprehensive selection of aquaculture species based on element complementarity;

[0012] Construct a diversified and integrated aquaculture system;

[0013] Optimize the stocking ratio of the constructed diversified integrated aquaculture system;

[0014] The effectiveness of the largemouth bass multi-species integrated aquaculture system was verified using the Ecopath model.

[0015] Preferably, the step of screening aquaculture species based on element complementarity specifically includes:

[0016] Using largemouth bass as the main cultured species, the carbon, nitrogen, and phosphorus content and their stoichiometric ratios in their feces were measured.

[0017] Two or more candidate fish species were selected, and the carbon, nitrogen, and phosphorus content and their stoichiometric ratios in their muscle tissue were measured. The growth performance and nutrient utilization rate of these candidate fish species after feeding on largemouth bass feces, uneaten food, and natural particulate organic matter were also measured.

[0018] Based on the principle of chemometric complementarity, fish species whose muscle carbon, nitrogen, and phosphorus ratios are closest to those in largemouth bass feces were screened. If the candidate fish species showed higher secondary assimilation capacity and growth rate after feeding on largemouth bass feces, and could reduce the nitrogen and phosphorus content in their excrement, then the species was preliminarily identified as a complementary species.

[0019] Preferably, the step of constructing a diversified integrated aquaculture system specifically includes:

[0020] Main species identified for farming: Largemouth bass;

[0021] Filter-feeding species identified: Bighead carp;

[0022] Benthic omnivorous species: crucian carp.

[0023] Preferably, the step of optimizing the stocking ratio of the constructed multi-element integrated aquaculture system specifically includes: conducting experiments with different stocking ratio gradients for the constructed multi-element integrated aquaculture system, monitoring the growth performance, feed utilization rate, water nitrogen concentration in three states and greenhouse gas emission flux of largemouth bass, and determining the optimal stocking ratio of the multi-element integrated aquaculture system as: largemouth bass: bighead carp: crucian carp = 18:2:9 through comparative analysis.

[0024] Preferably, the step of verifying the effectiveness of the largemouth bass multi-element integrated aquaculture system using the Ecopath model specifically includes: constructing an Ecopath nutrient kinetic model; dividing the constructed optimal multi-element integrated aquaculture system into functional groups that include at least largemouth bass, bighead carp, crucian carp, shrimp, snails, zooplankton, phytoplankton, attached organisms, feed, feces, and detritus; inputting the biomass, productivity to biomass ratio, feed intake to biomass ratio, and food composition matrix of each functional group; analyzing the model output results; and obtaining the overall characteristic parameters of the system, including: total system flow, total amount of detritus flowing into the system, Finn's circulation index, connectivity index, and total primary productivity / total respiration.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Growth and feed utilization: By constructing an optimal multi-element integrated aquaculture system, this invention increases the feed utilization rate of largemouth bass from 82.01% in monoculture systems to 102.34%, and the weight gain rate from 239.75% in monoculture systems to 267.19%.

[0027] 2. Improve nitrogen utilization efficiency: By constructing an optimal multi-element integrated aquaculture system, this invention significantly increases the total nitrogen retention rate of feed from 24.99% in monoculture systems to 32.52%, while reducing unused nitrogen discharged into water bodies and bottom sediments from 65.37% to 42.46%, proving that the system is more efficient in utilizing nitrogen.

[0028] 3. Significantly improves water quality: This invention can effectively reduce the concentrations of NH4⁺ (82.14% lower than monoculture systems), NO2⁻ (65.15% lower) and NO3⁻ (46.53% lower) in water bodies, and significantly reduce the emission fluxes of greenhouse gases N2O (38.58% lower) and CH4 (53.94% lower).

[0029] 4. Optimize the energy flow of the ecosystem: Compared with the monotrophic system, the multi-economy system constructed by this invention has a lower proportion of energy flowing into the detritus, which not only improves the efficiency of energy cycling in the food chain, but also reduces the accumulation of energy in the bottom sediment as waste.

[0030] 5. Provides a scientific basis for variety selection: The method of this invention is the first to use ecological chemometrics as a quantitative indicator for the selection of integrated aquaculture varieties, explaining the theoretical basis of variety matching from the perspective of "complementary elements", and overcoming the limitations of traditional reliance on experience. Attached Figure Description

[0031] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1 This is a flowchart illustrating the construction method of the largemouth bass multi-element integrated aquaculture system based on element complementarity according to the present invention.

[0033] Figure 2a A schematic diagram of material flow between different trophic levels in a monoculture system of largemouth bass;

[0034] Figure 2b This is a schematic diagram of material flow between different trophic levels in a largemouth bass-bighead carp-crucian carp (18:2:9) integrated aquaculture system. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0036] Specifically, this invention provides a method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity, such as... Figure 1 As shown, the method includes the following steps:

[0037] S1: Comprehensive selection of aquaculture species based on element complementarity;

[0038] Specifically, step S1 includes the following steps:

[0039] Step S11: Using largemouth bass as the main cultured species, determine the carbon (C), nitrogen (N), and phosphorus (P) content and their stoichiometric ratio (C:N:P) in their feces.

[0040] Step S12: Select two or more candidate fish species, and determine the C, N, and P content and their stoichiometric ratios in their muscle tissue. Also, determine the growth performance (weight gain rate, specific growth rate) and nutrient utilization rate of these candidate fish species after feeding on largemouth bass feces, largemouth bass feed, and natural pelleted organic matter.

[0041] Step S13: Based on the principle of stoichiometric complementarity, fish species whose muscle C:N:P ratio is closest to that of largemouth bass feces are selected. If the candidate fish species exhibit higher secondary assimilation capacity and growth rate after consuming largemouth bass feces, and can significantly reduce the N and P content in their excrement, then the species is preliminarily identified as a complementary species.

[0042] S2: Construct a diversified integrated aquaculture system;

[0043] Specifically, the constructed diversified integrated aquaculture system includes:

[0044] Main species identified for farming: Largemouth bass;

[0045] The filter-feeding species was determined to be the bighead carp. In this embodiment, the bighead carp was chosen instead of the silver carp because it exhibits greater stability in utilizing the feces of the largemouth bass and maintaining the C:N balance, and also demonstrates superior growth performance.

[0046] The selected benthic omnivorous species is crucian carp. In this embodiment, crucian carp was chosen instead of yellow catfish or yellowtail gudgeon because crucian carp has the highest nutrient utilization rate in the feces of largemouth bass, exhibits a significantly better growth rate than other benthic fish, and can effectively reduce the phosphorus content in the feces.

[0047] S3: Optimize the stocking ratio of the constructed diversified integrated aquaculture system;

[0048] Specifically, experiments were conducted in outdoor ponds or enclosures, with different stocking ratio gradients (bass monoculture group (LB), bass-bighead carp integrated culture group (LB+CB), bass-crucian carp integrated culture group (LB+CA), bass-bighead carp-crucian carp integrated culture group A (LB18:CB3:CA6), bass-bighead carp-crucian carp integrated culture group B (LB18:CB2:CA9), and bass-bighead carp-crucian carp integrated culture group C (LB18:CB1:CA12)) for the multi-element integrated aquaculture system constructed in step S2. The growth performance (weight gain rate, specific growth rate), feed utilization rate, water nitrogen concentrations (NH4⁺, NO2⁻, NO3⁻), and greenhouse gas (N2O, CH4) emission fluxes) of the largemouth bass were monitored. Through comparative analysis, the optimal stocking ratio for the multi-element integrated aquaculture system was determined to be: largemouth bass: bighead carp: crucian carp = 18:2:9.

[0049] S4: Validate the effectiveness of the largemouth bass multi-species integrated aquaculture system using the Ecopath model.

[0050] Specifically, an Ecopath trophic kinetic model is constructed. The Ecopath model is a suitable modeling tool for quantitative evaluation from the perspective of "overall energy flow, trophic level structure, and material cycling of the ecosystem." Based on the optimal aquaculture system in step S3, functional groups are divided, including at least largemouth bass, bighead carp, crucian carp, shrimp, snails, zooplankton, phytoplankton, attached organisms, feed, feces, and detritus. The biomass (B), P / B coefficient (productivity to biomass ratio), Q / B coefficient (feed intake to biomass ratio), and food composition matrix (which can be corrected using stable isotope data) of each functional group are input. The model output is analyzed to obtain the overall characteristic parameters of the system, including: total system throughput (TST), total inflow into detritus groups, Finn's circulation index (FCI), connectivity index (CI), and total primary productivity / total respiration (TPP / TR).

[0051] The method of the present invention will be further described below with reference to specific embodiments.

[0052] Example 1: Selection of the most suitable species for polyculture of largemouth bass based on element complementarity

[0053] A controlled experiment was conducted in an indoor aquaculture system for 60 days. Five candidate fish species—silver carp, bighead carp, crucian carp, yellow catfish, and yellowtail gudgeon—were fed commercial largemouth bass feed, largemouth bass feces, and natural particulate organic matter (POM) as food sources. After the experiment, the C, N, and P contents of the muscle and feces of each fish were measured.

[0054] The C:P ratio in largemouth bass feces was 14.81, and the N:P ratio was 1.88, indicating high nitrogen and phosphorus content. Compared with silver carp, the stoichiometric ratio of bigmouth bass muscle was close to that of largemouth bass feces, indicating that bigmouth bass had a high assimilation efficiency of largemouth bass farming waste. The nutrient absorption rate of bigmouth bass from largemouth bass feces (0.70% / d) was higher than that of silver carp (0.52% / d), and the C:N (4.26) and C:P (18.02) of bigmouth bass muscle showed stronger stability than those of silver carp. In terms of growth indicators, the weight gain rate of bigmouth bass fed with largemouth bass feces (70.59%) was higher than that of silver carp (58.78%). The stoichiometric ratios (C:N) (4.35) and (C:P) (16.18) of the muscle of crucian carp fed with largemouth bass feces were close to those of largemouth bass feces, indicating that the crucian carp had a high assimilation efficiency of largemouth bass aquaculture waste. At the same time, the crucian carp showed a high secondary assimilation capacity after feeding on largemouth bass feces, with a specific growth rate (SGR) of 80.23% and a decrease in P content in the feces, indicating that the crucian carp enriched and absorbed nitrogen and phosphorus elements from the largemouth bass feces. The nutrient absorption rate of crucian carp from largemouth bass feces (1.75% / d) was higher than that of yellow catfish (0.97% / d) and yellowtail gudgeon (1.61% / d). The weight gain rate of crucian carp fed with largemouth bass feces (87.11%) was higher than that of yellow catfish (36.57%) and yellowtail gudgeon (74.81%). Based on the principle of complementary eco-stoichiometry, the high nitrogen and phosphorus emissions of largemouth bass can be compensated by the elemental requirements of bighead carp and crucian carp.

[0055] Example 2: Determination of the optimal integrated aquaculture ratio of largemouth bass-bighead carp-crucian carp and verification of system effectiveness

[0056] An outdoor pond experiment was conducted at the Shanghai Ocean University Binhai Base for 56 days. Largemouth bass monoculture (LB), bass-bighead silver carp binary culture (LB+CB), bass-crucian carp binary culture (LB+CA), and three different ratios of bass-bighead silver carp-crucian carp ternary cultures were established: LB18:CB3:CA6 (largemouth bass:bighead silver carp:crucian carp = 18:3:6), LB18:CB2:CA9 (18:2:9), and LB18:CB1:CA12 (18:1:12), with three replicates per group.

[0057] Growth and feed utilization: The weight gain rate (267.19%) and feed utilization rate (102.34%) of the LB18:CB2:CA9 group of largemouth bass were significantly higher than those of the monoculture group and other polyculture groups (P<0.05), which were 28.44% and 20.33% higher than those of the monoculture largemouth bass control group, respectively, proving that this ratio is the optimal ratio.

[0058] Water purification effect: At the end of the experiment, the contents of NH4⁺, NO2⁻, and NO3⁻ in the water of the LB18:CB2:CA9 group were reduced by 82.14%, 60.42%, and 46.53%, respectively, compared with the monoculture group; the emission fluxes of greenhouse gases N2O and CH4 were reduced by 38.58% and 53.94%, respectively. This indicates that the model has a significant emission reduction effect.

[0059] Nitrogen use efficiency: via δ 15 Nitrogen isotope tracing technology was used to quantitatively analyze the fate of feed nitrogen (as shown in Table 3-8). In the monoculture group (LB), only 24.99% of feed nitrogen was converted into fish biomass, while as much as 65.37% of nitrogen remained in the water and bottom sediment environment. However, in the LB18:CB2:CA9 group, through secondary interception and assimilation by bighead carp and crucian carp, the total nitrogen retention rate of the system was significantly increased to 32.52%, while nitrogen emissions into the environment decreased to 42.46%. This strongly demonstrates, from the microscopic level of nutrient cycling, that the method of this invention achieves the dual goals of "increasing efficiency and reducing pollution."

[0060] Example 3: Ecopath (Ecological Network) Model Validation

[0061] Based on the measured data from Example 2, Ecopath models were constructed for both the largemouth bass monoculture system (LB) and the optimal largemouth bass-bighead carp-crucian carp (18:2:9) (LB18:CB2:CA9). Functional groups included largemouth bass, bighead carp, crucian carp, shrimp, snails, zooplankton, phytoplankton, attached organisms, chironomid larvae, bass feces, aquatic debris, bottom sediment debris, and feed. The food matrix parameters were determined by stable isotopes (δ¹⁸O). 13 C、δ 15 N) Constrain the analysis results.

[0062] like Figure 2a , Figure 2b As shown, from the perspective of macroscopic energy flow, the total energy flowing into the detritus in the ternary integrated aquaculture system accounts for 56.21% of the total energy flow (TST), significantly lower than the 65.95% in the monoculture system. This means that approximately 9.74% of the energy that would otherwise be deposited as waste is recycled back into the food chain. Compared to the monoculture model, the ternary integrated aquaculture model has less energy entering the detritus pool, resulting in a more optimized energy flow structure.

[0063] System maturity: The TPP / TR ratio of the LB18:CB2:CA9 group was 2.53, which was much lower than the 4.74 of the LB group and closer to the theoretical value of 1 for a mature ecosystem, indicating that multi-species polyculture significantly improved the maturity and stability of the system.

[0064] Connectivity and Circulation Indices: The connectivity index (CI) of the LB18:CB2:CA9 group was 0.375, and the omnivorousness index (SOI) was 0.089, both higher than those of the monoculture group (CI=0.271, SOI=0.054). This indicates that the food web structure of the ternary integrated aquaculture system is more complex, the connections are tighter, and the internal material circulation efficiency is higher.

[0065] The macro-quantitative analysis results of the Ecopath model, from the global perspective of energy flow and material cycling in the ecosystem, corroborate the phenotypic data and element flow data in Example 2, and together demonstrate the significant superiority of the largemouth bass-bighead carp-crucian carp (18:2:9) ternary integrated aquaculture model constructed in this invention in terms of emission reduction and efficiency improvement.

[0066] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity, characterized in that, The method includes the following steps: Comprehensive selection of aquaculture species based on element complementarity; Construct a diversified and integrated aquaculture system; Optimize the stocking ratio of the constructed diversified integrated aquaculture system; The effectiveness of the largemouth bass multi-species integrated aquaculture system was verified using the Ecopath model.

2. The method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity according to claim 1, characterized in that, The steps for comprehensive aquaculture species selection based on element complementarity specifically include: Using largemouth bass as the main cultured species, the carbon, nitrogen, and phosphorus content and their stoichiometric ratios in their feces were measured. Two or more candidate fish species were selected, and the carbon, nitrogen, and phosphorus content and their stoichiometric ratios in their muscle tissue were measured. The growth performance and nutrient utilization rate of these candidate fish species after feeding on largemouth bass feces, uneaten food, and natural particulate organic matter were also measured. Based on the principle of chemometric complementarity, fish species whose muscle carbon, nitrogen, and phosphorus ratios are closest to those in largemouth bass feces were screened. If the candidate fish species showed higher secondary assimilation capacity and growth rate after feeding on largemouth bass feces, and could reduce the nitrogen and phosphorus content in their excrement, then the species was preliminarily identified as a complementary species.

3. The method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity according to claim 1, characterized in that, The steps for constructing a diversified integrated aquaculture system specifically include: Main species identified for farming: Largemouth bass; Filter-feeding species identified: Bighead carp; Benthic omnivorous species: crucian carp.

4. The method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity according to claim 1, characterized in that, The steps for optimizing the stocking ratio of the constructed multi-species integrated aquaculture system specifically include: conducting experiments with different stocking ratio gradients for the constructed multi-species integrated aquaculture system, monitoring the growth performance, feed utilization rate, water nitrogen concentration in three states and greenhouse gas emission flux of largemouth bass, and determining the optimal stocking ratio of the multi-species integrated aquaculture system as: largemouth bass: bighead carp: crucian carp = 18:2:9 through comparative analysis.

5. The method for constructing a multi-element integrated aquaculture system for largemouth bass based on element complementarity according to claim 1, characterized in that, The steps for verifying the effectiveness of the largemouth bass multi-species integrated aquaculture system using the Ecopath model specifically include: constructing an Ecopath nutrient kinetic model; dividing the constructed optimal multi-species integrated aquaculture system into functional groups that include at least largemouth bass, bighead carp, crucian carp, shrimp, snails, zooplankton, phytoplankton, attached organisms, feed, feces, and detritus; inputting the biomass, productivity-to-biomass ratio, feed intake-to-biomass ratio, and food composition matrix of each functional group; analyzing the model output results; and obtaining the overall characteristic parameters of the system, including: total system flow, total amount of detritus entering the system, Finn's circulation index, connectivity index, and total primary productivity / total respiration.

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