CN116655119A

CN116655119A - Method for repairing shallow lake ecosystem by fish and grass combined regulation and control

Info

Publication number: CN116655119A
Application number: CN202310638268.7A
Authority: CN
Inventors: 李为; 郭超; 刘家寿; 李诗琦; 王勇庆; 施学峰; 周裔煊; 廖传松; 苑晶
Original assignee: Jiangsu Sino French Water Co ltd; Institute of Hydrobiology of CAS
Current assignee: Jiangsu Sino French Water Co ltd; Institute of Hydrobiology of CAS
Priority date: 2023-06-01
Filing date: 2023-06-01
Publication date: 2023-08-29
Anticipated expiration: 2043-06-01
Also published as: CN116655119B

Abstract

The application discloses a method for repairing a shallow lake ecosystem by fish and grass combined regulation, which belongs to the technical field of environmental protection and specifically comprises the following steps: (1) Investigation is carried out on the current situation of the water environment of the lake and the current situation of the aquatic organism resource, and the problems of the ecological system of the lake are diagnosed; (2) optimizing the fish community structure; and (3) reconstructing a submerged plant community. The application carries out ecological restoration of the lake ecological system from the view of the structural and functional integrity and stability of the ecological system, has obvious restoration effect on the lake ecology, and obtains good ecological and social benefits. Moreover, the method has strong technical feasibility and applicability and has good popularization and application prospects.

Description

Method for repairing shallow lake ecosystem by fish and grass combined regulation and control

Technical Field

The application belongs to the technical field of environmental protection, and particularly relates to a method for repairing a shallow lake ecosystem by fish and grass combined regulation.

Background

Since innovation is open, along with the rapid development of social economy in China, the ecological environment condition in China is worsened, and part of areas are used for predating natural resources to develop, so that a series of ecological environment problems such as water and soil loss, water resource pollution, soil pollution and the like are caused, wherein lake water eutrophication is one of the main ecological environment problems at present. Along with the rapid development of social economy and the acceleration of the urban process, the water quality of the lake water body is gradually deteriorated by the introduction of a large amount of nutrient substances, the aquatic organism structure is unbalanced, the lake ecological system is seriously degraded, and the area of the national eutrophication lake is increased by nearly 60 times in the last 40 years. The deterioration of the ecological environment of the lake is not only against the ecological civilization and sustainable development concept, but also does not meet the target of increasingly struggling for people to live well. Under the background of gradual aggravation of lake eutrophication, the restoration and protection management of the lake ecosystem are more focused and researched, and a series of lake ecological restoration technologies are also developed.

The ecological restoration technology of lakes can be mainly divided into three types of physical restoration, chemical restoration and biological restoration, wherein the biological restoration technology is most widely applied. Bioremediation is mainly considered from the aspects of environmental protection and low cost, and nutrient salts in water bodies are regulated and controlled through aquatic vegetation, aquatic microorganisms, aquatic animals and other aquatic organisms so as to improve the polluted water body environment. At present, the most important method for restoring and reconstructing the submerged plant community in lakes is restoration, but when most lakes are restored ecologically by adopting the method, restoration of the submerged plants is unsuccessful and the expected effect cannot be achieved. The normal survival and growth of submerged plants in lakes requires the necessary nutritional conditions, proper substrate conditions, transparency to water depth ratio not less than 1/3 and reasonable fish community structure to be met. In lakes with eutrophication of water bodies, the nutrient conditions and substrate conditions required by the growth of submerged plants can be met, the transparency and water depth ratio in a proper shallow water area can be more than 1/3, but the fish community structure is often unreasonable, and the characteristics of the fish community structure are that herbivorous fishes, bottom omnivorous fishes and small zooplankton edible fishes are high in abundance and large and medium-sized fish edible fishes and clastic fishes are low in abundance, so that the field planting and the growth of the submerged plants are directly influenced, and the improvement of the environmental conditions required by the growth of the submerged plants is not facilitated. In the prior art, when the submerged plants are adopted to carry out ecological restoration of lakes, the influence of fishes on the field planting and the growth of the submerged plants is usually ignored, and the regulation and optimization of the fish community structure are not known, so that the submerged plants cannot survive and grow normally, and finally the ecological restoration effect is difficult to achieve.

Therefore, how to develop and integrate effective lake ecological restoration and environmental protection technologies, promote the health and stability of the lake ecological system, promote green development, and realize the harmonious symbiosis of people and nature is a technical problem which needs to be solved by the technicians in the field.

Disclosure of Invention

In order to solve the technical problems, the application provides a method for repairing the ecological system of the shallow lake by combining fish and grass.

In order to achieve the above purpose, the present application provides the following technical solutions:

a method for repairing a shallow lake ecosystem by fish and grass combined regulation comprises the following steps:

(1) Investigation is carried out on the current situation of the water environment of the lake and the current situation of the aquatic organism resource, and the problems of the ecological system of the lake are diagnosed;

(2) Optimizing the fish community structure: based on the current situation of the lake fish community structure, the fish community is adjusted through fish stocking, fishing and removing, the structure and the function of the fish community are optimized, so that the conversion and utilization efficiency of bait resources in the lake is improved, and meanwhile, basic guarantee is provided for restoration and reconstruction of the submerged plant community;

in the fish stocking, the fish comprises fish feeding fishes, filter feeding fishes and chip feeding fishes;

in the fish catching and removing, the fish comprises herbivorous fishes, bottom omnivorous disturbing fishes and zooplankton edible fishes.

(3) Reconstructing submerged plant communities: the submerged plants are selected based on the current situation of the submerged plant community in the lake, and the submerged plant community is planted through artificial and natural recovery, so that the structure and the function of the submerged plant community are optimized, and the absorption and utilization efficiency of nutrient salts in the lake and the self-cleaning capacity of the water body are improved.

Preferably, the lake in the step (1) is a shallow fresh water lake in which the water body is in an eutrophication state;

the water environment comprises water quality physical and chemical characteristics, nutrient salt characteristics and substrate sediment of lakes;

the aquatic resources include plankton, benthonic animals, higher aquatic plants and fish.

The beneficial effects are that: provides a basic basis for reasonably regulating and controlling the fish community structure and reasonably selecting a proper submerged plant recovery area.

Preferably, the fish feeding fishes in the step (2) comprise culter ilishaeformis, mongolian culter, mandarin fish and snakehead fish, and the stocking amountIt mainly directly preys and utilizes small zooplankton edible fishes with over-high abundance in lakesClass and small omnivorous fish;

the filter-feeding fish comprises silver carp and bighead carp, wherein the stocking amount ratio of the silver carp to the bighead carp is not less than 1:1, and the stocking amount is not less than 1:1

The clastic fishes include, but are not limited to, xenocypris davidi, plagiognathops microlepis, and the stocking quantity F _S ＝C _S ·V·(19.56％Q ₁ +22.60％Q ₂ )×3900000/(3560Q ₁ +3350Q ₂ ) It mainly ingests plant debris and particulate organics in the water;

wherein,,

the F is _Y 、F _L 、F _S The unit of the stocking amounts of the fish feeding fishes, the filter feeding fishes and the chip feeding fishes is ton;

a is the maximum utilization rate allowed by the bred fish to the bait organisms;

k is the bait coefficient of the bred fish to the bait organisms;

the B is _Y The annual average biomass of small fishes and shrimps is expressed in g/m ² ；

The P/B is the ratio of the annual production of the bait organisms to the annual average biomass;

the S is lake area, and the unit is km ² ；

The B is _P The biomass is the annual average biomass of phytoplankton, and the unit is mg/L;

the B is _Z1 The biomass is the annual average biomass of zooplankton, and the unit is mg/L;

the V is lake volume; c (C) _S The annual average content of organic carbon in the organic scraps is mg/L;

the Q is ₁ The silver carp in the lake accounts for the biomass proportion of silver carp and bighead carp;

the Q is ₂ Is the biomass proportion of bighead in silver carp and bighead in lakes.

The beneficial effects are that: the stocking amount of different fishes is scientifically determined, and the rationality, scientificity and feasibility of the regulation of the fish community structure are ensured.

Preferably, the maximum utilization rate a and the bait coefficient k of different types of the bred fish for the bait organisms are shown in the following table:

the beneficial effects are that: the characteristics, conversion efficiency and nutrition content of different bait types are different, so that the allowable maximum utilization rate and bait efficiency are greatly different, and the parameters given by the table are summarized based on a large number of research experiments, so that the scientificity and the accuracy of the bait type bait are ensured.

Preferably, the P/B coefficients of different bait organisms in lakes of different areas are shown in the following table:

the beneficial effects are that: the lake temperature and nutrient salt in different areas have larger difference, so that the P/B coefficients of phytoplankton, zooplankton and small fishes and shrimps also have certain difference. The application provides corresponding parameters by dividing the regions, so that the scientificity, the accuracy and the applicability of the whole result can be ensured.

Preferably, the herbivorous fishes in the step (2) comprise grass carp, megalobrama amblycephala, triangular bream and catharantha rosea, which mainly ingest higher aquatic plants, and are particularly unfavorable for survival and growth of submerged plants;

the bottom omnivorous disturbance fishes comprise carps, crucian carp and black carp, mainly inhabit and forge at the bottom of a lake, are particularly unfavorable for field planting of submerged plants planted manually and germination of submerged plant seeds by broadcasting, and are unfavorable for the growth of plants due to the fact that turbidity of water body is increased by disturbance of sediment;

the zooplankton edible fishes comprise -like, new whitebait in Taihu lake, pond fish and coilia ectenes, mainly feed on zooplankton, reduce the biomass of the zooplankton, facilitate reducing the predatory pressure on the zooplankton, and strengthen the zooplankton population, thereby controlling the abundance of the zooplankton;

the initial stage of the planting is a period that the whole lake fish community structure is adjusted and optimized to not influence the normal growth of submerged plants, the biomass of the fishes is reduced and controlled as much as possible, and nets for catching the fishes include but are not limited to a stab net, a net and a purse net.

Preferably, the selecting principle of the submerged plant in the step (3) includes:

a. the original seeds existing in the lake in advance are avoided to be introduced with foreign seeds;

b.3 submerged plants with different life history characteristics are planted or broadcast simultaneously;

c. at least 1 perennial submerged plant;

the beneficial effects are that: herbivorous fishes such as grass carp, megalobrama amblycephala, triangular bream and vincam, and bottom omnivorous disturbance fishes such as carp, crucian carp and black carp have adverse effects on the field planting and growth of submerged plants, so that the fishes need to be removed; according to the application, the removal and control of zooplankton edible fishes like , taihu new whitebait, pond male fish, lake coilia ectenes and the like are mainly carried out to relieve the predatory pressure of the zooplankton, enlarge the zooplankton population, inhibit the abundance of the zooplankton, improve the transparency of the lake and provide necessary illumination conditions for the growth of submerged plants.

Preferably, the submerged plant comprises any one of herba Sonchi Oleracei, goldfish algae, sargassum gracile, sargassum spicatum, herba Malloti Apeltae, herba Onchi Oleracei, and Potamogeton crispus;

the beneficial effects are that: the water treatment agent is a common submerged plant in shallow lakes, and has obvious effects of absorbing and utilizing nutrient salts in water and improving self-cleaning capacity and transparency of the water.

Preferably, the planting method in the step (3) comprises seed sowing and plant transplanting;

the transparency and water depth ratio of the planted area is not less than 1/3, the substrate is suitable for the field planting and growth of the selected submerged plants, and fish in the area cannot negatively influence the germination and growth of the submerged plants;

the beneficial effects are that: the application defines the basic conditions required to be met in the submerged plant planting area, and can ensure the field planting, survival and normal growth of submerged plants.

Preferably, the plant transplanting comprises one or any of the following methods:

1) Cutting the seedlings of the submerged plants into bottom mud with roots;

2) Cutting mature plants of submerged plants into 15-30cm nutrition segments, and cutting the nutrition segments into bottom mud;

3) Wrapping the submerged plant seedlings and the nutrition sections by nutrition soil, and then planting at fixed points;

4) Soaking submerged plant seeds, and uniformly stirring with nutrient mud, wherein the seed sowing amount is 0.5-2.0g/m ² The plant transplanting quantity is 200-500g/m ² 。

The beneficial effects are that: the measures can promote and ensure the survival and growth of submerged plants and promote the rapid construction of submerged plant communities.

Preferably, the method further comprises the following steps:

(4) Daily management

Setting a submerged plant planting test area in a lake at the initial stage of submerged plant community planting, constructing a fence at the periphery of the test area to select proper submerged plant types, putting filter-feeding fish silver carps, plagiognathops microlepis and fish-feeding fish ilishaeformis in the fence, removing and reducing biomass of herbivorous fishes, bottom omnivorous fishes and zooplankton edible fishes outside the fence, monitoring and timely clearing the herbivorous fishes, the bottom omnivorous fishes and the zooplankton edible fishes in the fence at regular intervals, and opening or removing the fence when the fish structure of the lake is adjusted and optimized to not influence the growth of the submerged plant;

when the coverage of the submerged plants is recovered to more than 30% of the lake, the plants which are about to die or die are timely harvested and removed according to the life history characteristics of the submerged plants; half a month after each year of fish release, fish individuals that die due to mechanical damage or disease are cleared in time.

The beneficial effects are that: harvesting and removing plants to be apoptotic or dead in time and removing fish individuals dead due to mechanical damage or diseases in time are mainly used for avoiding secondary pollution of the substances to lakes.

The application provides a method for restoring a shallow lake ecological system by combining fish and grass, which carries out ecological restoration of the lake ecological system from the aspects of structural integrity and functional stability of the ecological system and emphasizes quantitative investigation on the water quality, substrate, bait organisms and fish community structure of the lake before planting the aquatic grass to restore and reconstruct a submerged plant community. According to the current situation of the water quality, substrate and submerged plant community of the lake, selecting proper submerged plants, and reconstructing the submerged plant community at a proper position selected by the lake through the measures of artificial planting and natural recovery; meanwhile, based on the current situation of the structure of the fish communities in the lakes, the fish communities are optimized and adjusted through scientific fish stocking, fishing and removing, the conversion and utilization efficiency of bait resources in the lakes is improved, and more importantly, the necessary survival conditions are provided for survival and growth of submerged plants.

The application pays attention to the preference of the pioneer species of the submerged plants and at least recovers the submerged plants with 3 different life history characteristics, can ensure that the submerged plants form a population rapidly and keep higher diversity in the middle and later stages, thereby forming a stable submerged plant community and greatly improving the self-cleaning capability and stability of the lake ecosystem. In addition, before planting aquatic weeds, the application explores the current situation of the fish community structure of the lake, determines the technical strategy of optimizing and adjusting the fish community structure based on the fish community structure characteristics, ensures that the fish community does not adversely affect the field planting, survival and growth of aquatic weeds, can provide good environmental conditions for rapid recovery of the aquatic plant community, can improve the conversion and utilization efficiency of bait resources in the lake, and integrally improves the integrity, stability and health degree of the lake ecological system.

The application has been applied to the technique of lakes in the emergency water source area of the mature city in Jiangsu province, puppet lake in Kunshan city, and the like, has obvious ecological restoration effect on the lakes, and obtains good ecological and social benefits. Moreover, the method has strong technical feasibility and applicability and has good popularization and application prospects.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

FIG. 1 shows the variation of NPUE and BPUE of small zooplankton edible fishes in the process of combined regulation and control of lake fish and grass in 2017-2021 year old emergency water source area in example 1;

FIG. 2 shows the variation of coverage and biomass of submerged plant communities in the process of combined regulation of lake fish and grass in 2017-2021 year old emergency water source area in example 1;

FIG. 3 is a schematic diagram showing the total density of phytoplankton and the density of cyanobacteria gate in the process of combined regulation and control of lake fish and grass in 2017-2021 year-old emergency water source area;

wherein, (a) is a total density change schematic diagram of phytoplankton, and (b) is a cyanobacteria density change schematic diagram;

FIG. 4 is a schematic diagram showing the change of transparency and chlorophyll a content in the process of combined regulation and control of lake fish and grass in 2017-2021 year old emergency water source area in example 1;

wherein, (a) is a lake transparency change schematic diagram, and (b) is a chlorophyll a content change schematic diagram;

FIG. 5 shows the variation of fish community composition during puppet, lake fish and grass joint regulation in 2012-2014 in example 2;

FIG. 6 shows variation of submerged plant species number and coverage during the combined control of puppet lake fish grass in 2011-2015 of example 2;

FIG. 7 shows the changes in water transparency and chlorophyll a content during the combined control of the puppet, huyucao, 2011-2015 years in example 2.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description.

Example 1

A method for repairing shallow lake ecosystem by combining fish and grass is disclosed, which is used for treating the lake of the emergency water source of the city of Jiangsu province.

(1) Lake water environment and aquatic organism resource investigation and problem diagnosis

The lake of the frequent emergency water source is positioned in the north of the frequent city of Jiangsu province, the lake area is close to the Yangtze river, and the water surface area is 0.98km ² The water depth gradually increases from the coastal zone to the central zone, the water depth variation range is between 1m and 6.5m, the average water depth is 4.5m at the normal water level, and the water source is taken from the Yangtze river and is the only emergency standby water source in the conventional city. The lake is formally put into use in month 4 of 2016, but the biomass of algae in the water source area of month 6-9 of 2016 is obviously increased, the phenomenon of blue algae bloom appears in partial areas, the water body is in a medium eutrophication state, and meanwhile, the water body smelling substance dimethyl isoborneol (2-MIB) has higher content, and the water supply has earthy smell, so that the water quality of the water supply and the safety of water for residents are influenced. The investigation shows that the lake whole lake has no submerged plant community, the fish community has single structure and low diversity, the small plankton edible fishes at the middle and upper layers are mainly used as dominant species, and the ecological system structure and the function are poor.

According to the problems faced by the lake region, the water body ecological system is restored by the fish and grass combined regulation and control method in 2017. The method specifically comprises the following steps:

(2) Optimization of fish community structure

Based on the current situation of the lake fish community structure, the filter feeding fish silver carp and bighead carp are put in the water tank, wherein the put amount is 99316kg; feeding fish-eating fish snakeheads, culter ilishaeformis and mandarin fish with the feeding amount of 1867kg; fishing grass carp of herbivorous fishes and megalobrama amblycephala, wherein the fishing amount is 368kg; the fishing amount of the bottom layer omnivorous fish crucian carp is 2450kg.

(3) Submerged plant community reconstruction

Based on the current situation of the submerged plant community in the lake, selecting proper submerged plants to reconstruct the submerged plant community in the lake through artificial planting and natural restoration, wherein the submerged plant varieties include, but are not limited to, herba sophorae flavescentis, goldfish algae, hydrilla verticillata, spica, malaytea scuba, microdootheca, potamogeton crispus and the like; the planting mode comprises seed sowing and plant transplanting. At the initial stage of planting (the period of time when the whole lake fish community structure is adjusted and optimized to not influence the normal growth of submerged plants), constructing a fence around the submerged plant reconstruction area, and removing herbivorous fishes, bottom omnivorous disturbance fishes and zooplankton edible fishes in the fence to avoid adverse effects of the three fishes on the field planting and the growth of the submerged plants in the fence; meanwhile, filter-feeding fish silver carp, plagiognathops microlepis serving as clastic fishes and culter ilishaeformis serving as fish are put into the enclosure, so that the density of phytoplankton and suspended particles in the enclosure is reduced, the transparency in the enclosure is improved, and necessary illumination conditions are provided for germination and growth of submerged plants.

(4) Daily management

At the initial recovery stage of the submerged plant (the period of time when the regulation and optimization of the whole lake fish community structure does not influence the normal growth of the submerged plant), monitoring and timely removing herbivorous fishes, bottom omnivorous disturbing fishes and zooplankton edible fishes in the enclosure at regular intervals, and opening or removing the enclosure when the regulation and optimization of the lake fish community structure does not influence the growth of the submerged plant;

when the coverage of the submerged plants is recovered to more than 30% of the lake, the water plants which are about to die or die are harvested and removed in time according to the life history characteristics of the submerged plants. Half a month after each year of fish release, fish individuals that die due to mechanical damage or disease are cleared in time.

After 5 years of monitoring, the ecological restoration effect is as follows:

(1) Small fish: as shown in fig. 1, by fish groupRegulating and controlling the structure of small zooplankton edible fishBream-like, etc.) density and biomass are significantly reduced. Compared with the 1 st year, the 2 nd year CPUEN and CPUEB respectively drop by 95.86% and 95.42%, and the 3 rd to 5 th years are always kept at a lower level along with the expansion of the submerged plant habitat although slightly fluctuating. Both CPUEN and CPUEB were significantly lower from year 2 to year 5 than from year 1. The reduction of the abundance of the zooplankton edible fishes is beneficial to the amplification of zooplankton populations, thereby having a control effect on zooplankton.

(2) Submerged plants: as shown in fig. 2, the coverage of submerged plants gradually increases by fish community regulation and submerged plant community reconstruction, and the submerged plant coverage in 2017-2021 is 0.20%, 0.90%, 4.11%, 10.79% and 20.81%, respectively; the species diversity of submerged plants also shows gradually rising vigor, and the leaf-black algae, the goldfish algae, the spike-shaped bromhidrosis, the water caltrop and the bitter grass initially form a relatively stable population in the emergency reservoir. The biomass of submerged plants is also gradually increased, and the biomass of submerged plants in 2017-2021 is 5g, 57g, 597g, 1313g and 1739g respectively. The increase of the coverage and species diversity of submerged plants and biomass effectively promotes the increase of the transparency of lakes in the frequent emergency water source area and inhibits the density of phytoplankton;

(3) Phytoplankton: as shown in FIG. 3, after the joint regulation of fish and grass, the total density of phytoplankton in 2017-2021 tends to decrease year by year, and the total density is 15.22×10 respectively ⁶ cells/L、14.69×10 ⁶ cells/L、9.05×10 ⁶ cells/L、4.11×10 ⁶ cells/L and 2.73X10 ⁶ cells/L; the density of the cyanobacteria gate also shows the gradual decline trend, and the cyanobacteria gate densities are respectively 9.03 multiplied by 10 ⁶ cells/L、7.14×10 ⁶ cells/L、5.39×10 ⁶ cells/L、2.42×10 ⁶ cell/L and 0.29×10 ⁶ cells/L；

(4) Water quality: as shown in figure 4, after the fish and grass are regulated and controlled in a combined way, the transparency of the lake in the conventional emergency water source area is obviously improved, and the chlorophyll a content is obviously reduced. The transparency of the water body in 2017-2021 is 108cm, 102cm, 132cm, 239cm and 333cm, and the chlorophyll a content is 24.77 mug/L, 26.10 mug/L, 6.95 mug/L, 9.55 mug/L and 9.62 mug/L;

(5) Ecological and economic benefits: from the assessment of emergency reservoir submerged plant coverage (20.81%) and average biomass (1739 g) of month 7 2021, 2021 submerged plant growth was expected to store (remove) 9471.8kg of nitrogen, and 3180.1kg of phosphorus. The quantitative stocking of the silver carps and the bighead carps realizes the effective control of the cyanobacterial bloom, and simultaneously, the quantitatively captured large-scale silver carps and bighead carps can remove nutritive salts taken away from water bodies, purify water quality and realize certain fishery benefits. The silver carp and bighead carp quantitatively caught in the emergency reservoirs in 2019 and 2021 can store (remove) 4965kg of nitrogen and 1077.9kg of phosphorus; meanwhile, the fishery benefit is about 162.7 ten thousand yuan.

Example 2

A method for repairing shallow lake ecosystem by combining fish and grass is disclosed, which is used for treating puppet lake in Kunshan city.

The puppet lake is located downstream of the Tai lake basin and is connected with the Yangcheng lake through a wild You Jing and a diversion box culvert, and is the only drinking water source place in Kunshan city of Jiangsu province. The lake surface is elliptical, the longest distance between the north and the south is 4.80km, the widest distance between the east and the west is 2.80km, and the area of the lake surface is 6.7km ² . Lake water is mainly derived from daily rainfall and Yang Cheng lakes, and the annual average water depth is 2.75m. Puppet's lake is mainly formed by reforming a cultivation lake through fishing, dredging, deepening and the like, and the water ecological system has simpler structure and function and poor maturity and stability. The investigation in 2011 shows that the lake has low richness of fish types, high biomass of bottom disturbing fishes and low biomass of fish eating fishes. The unreasonable fish community structure finally leads to almost complete extinction of the submerged plants in the lake, and the water quality of the lake has larger space-time fluctuation.

According to the problems faced by the lake region, the water body ecological system is restored in 2013-2015 by the fish-grass combined regulation method. The method specifically comprises the following steps:

(2) Optimization of fish community structure

Puppet developed regulation of fish populations mainly includes the following three aspects: firstly, adjusting the stocking quantity and proportion of the silver carp and bighead carp fries, wherein the total stocking quantity is 63940kg, and the stocking proportion of the silver carp and bighead carp is 2:1, a step of; secondly, increasing the stocking amount of fish-eating fishes (mandarin fish, snakehead fish, clarias leather, pelteobagrus fulvidraco, mongolian culter and culter ilishaeformis), wherein the stocking total amount is 25000kg; thirdly, the directional fishing of the bottom disturbance fishes (crucian carp, carp and the like) and herbivorous fishes (grass carp, megalobrama amblycephala and the like) is increased, and the fishing total amount is about 23000kg.

(3) Daily management

After 5 years of monitoring, the ecological restoration effect is as follows:

(1) Fish: as shown in FIG. 5, the ratio of the biomass of fish-eating fishes such as Erythroculter ilishaeformis, erythroculter mongolica, mandarin fish, etc. in the fish community is improved by the regulation of the fish community and the reconstruction of the submerged plant community, so as toThe zooplankton feeding small fish is controlled to a certain degree>The biomass in the community has fallen from 42% in 2012 to 8% in 2014. By directional fishing, the biomass of crucian carp is reduced from 19% in 2012 to 14% in 2014.

(2) Submerged plants: as shown in fig. 6, the abundance and coverage of submerged plant species are both significantly increased by fish population regulation and submerged plant population reconstruction, wherein the number of submerged plant species increased from 6 in 2011 to 12 in 2015; the coverage rises from less than 20% in 2011 to 73% in 2015, and a submerged plant community with Goldfish algae, potamogeton crispus, microodon japonicus, sonchus arvensis, hedyotis and Myrsina scillata as main dominant species is formed.

(3) Water quality: as shown in FIG. 7, after the joint regulation of fish and grass, the transparency of the puppet lake water body is increased from 50.75+ -9.78 cm in 2011 to 115.75 + -22.63 cm in 2015. In 2013-2015, the annual average transparency is 101.47 +/-17.33 cm, which is obviously higher than 51.38 +/-6.24 cm in 2011-2012. The average biomass of chlorophyll a was reduced from 6.30+ -1.34 μg/L in 2011 to 3.72+ -0.82 μg/L in 2015.

The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. The method for repairing the shallow lake ecosystem by combining the fish and grass is characterized by comprising the following steps of:

(2) Optimizing the fish community structure: based on the current situation of the lake fish community structure, the fish community is adjusted through fish stocking and fishing and removal, and the structure and the function of the fish community are optimized;

in the fish catching and removing process, the fishes comprise herbivorous fishes, bottom omnivorous disturbing fishes and zooplankton edible fishes;

(3) Reconstructing submerged plant communities: and selecting submerged plants based on the current situation of the lake submerged plant community, and artificially planting and naturally recovering the submerged plant community.

2. The method for restoring an ecological system of a shallow lake by combined regulation and control of fish and grass according to claim 1, wherein in the step (1), the lake is a fresh water shallow lake in which a water body is in an eutrophication state;

3. The method for regulating and repairing a shallow lake ecosystem by combining fish and grass according to claim 1, wherein in the step (2), the fish-feeding fishes comprise culter ilishaeformis, mongolian culter, mandarin fish, snakehead, and the stocking amount

The clastic fishes include, but are not limited to, xenocypris davidi, plagiognathops microlepis, and the stocking quantity F _S ＝C _S ·V·(19.56％Q ₁ +22.60％Q ₂ )×3900000/(3560Q ₁ +3350Q ₂ )；

Wherein,,

k is the bait coefficient of the bred fish to the bait organisms;

the S is lake area, and the unit is km ² ；

The B is _P Is the annual average life of phytoplanktonThe content is mg/L;

4. The method for regulating and repairing a shallow lake ecosystem by combining fish and grass according to claim 1, wherein the herbivorous fishes in the step (2) comprise grass carp, megalobrama amblycephala, triangular bream and catharanthus roseus;

the bottom omnivorous disturbance fish comprises carp, crucian carp and black carp;

the zooplankton edible fishes comprise -like, taihu new whitebait, pond fish and lake coilia ectenes;

the initial planting stage is a period when the whole lake fish community structure is adjusted and optimized to not influence the normal growth of submerged plants.

5. The method for repairing a shallow lake ecological system by combined regulation and control of fish and grass according to claim 1, wherein the principle of selecting submerged plants in the step (3) comprises the following steps:

c. at least 1 perennial submerged plant.

6. The method for repairing a shallow lake ecological system by combined regulation and control of fish and grass according to claim 5, wherein the submerged plant comprises any one of kucao, goldfish algae, hydrilla verticillata, spica, malaytea scurfpea, microdootheca and water caltrop.

7. The method for regulating and repairing a shallow lake ecosystem by combining fish and grass according to claim 1, wherein the planting mode in the step (3) comprises seed broadcasting and plant transplanting;

the transparency to water depth ratio of the planted area is not less than 1/3.

8. The method for regulating and repairing a shallow lake ecosystem by combining fish and grass according to claim 7, wherein the plant transplanting comprises one or any of the following methods:

1) Planting the submerged plant seedlings with roots in the bottom mud;

9. The method for repairing a shallow lake ecological system by combined regulation and control of fish and grass according to claim 1, further comprising the following steps:

(4) Daily management

when the coverage of the submerged plants is recovered to more than 30% of the lake, the plants which are about to die or die are timely harvested and removed according to the life history characteristics of the submerged plants; half a month after each year of fish release

When the fish individuals dead due to mechanical injury or disease are removed.