A method for quantitatively evaluating the degree of fish bubble disease under TDG supersaturation stress

Abstract

The application discloses a kind of quantitative evaluation methods of fish bubble disease degree under TDG supersaturation stress, first place fish under supersaturation stress under microscope respectively observe the amount of attached bubble of tail fin, anal fin, ventral fin, pectoral fin and dorsal fin and bleeding symptom, and take the photo of each fin;According to the total area S of photo measurement each fin, bubble coverage area S1, bleeding area S2;Calculate the bubble amount severity of each fin α1 and bleeding symptom severity α2;According to the size of α1 and α2, scoring is carried out, and the score t of each fin is calculated;According to the score of each fin, the comprehensive score T of fish is calculated;Determine the degree of fish bubble disease under TDG supersaturation stress.The application fills the vacancy of technical system of quantitative evaluation of fish bubble disease severity, and enriches the theoretical basis of water conservancy total dissolved gas supersaturation on fish impact evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ecological impact assessment of water conservancy projects on rivers, and particularly relates to a method for quantitatively evaluating the degree of fish bubble disease under TDG supersaturation stress. BACKGROUND

[0002] In recent years, in order to meet the growth of population and the development of social economy, water conservancy projects, especially hydropower dams, are increasing all over the world. Due to large discharge flow and high discharge water head, a large amount of gas is mixed into the water flow and flows into the downstream water body during dam discharge, especially high dam discharge. The excess dissolved gas is difficult to release back to the atmosphere in a short time, resulting in the supersaturation of total dissolved gas (TDG) in the downstream water body. During dam discharge, the TDG level in the downstream of many dams can reach 140%, and the TDG level in the downstream of some high-head power stations can even reach 180%. In addition to dam discharge, the thermal effect, groundwater, photosynthesis, waterfall, freezing and ocean wave in nature can also cause TDG supersaturation in water bodies.

[0003] TDG supersaturation caused by dam discharge and other factors will have extremely adverse effects on the organisms in the downstream water body, especially fish. When TDG is supersaturated, the supersaturated gas enters the fish body through the gills and circulates through the blood. When the blood flows through the fins and subcutaneous capillaries, gas emboli are formed, causing fish to suffer from bubble disease. The main external symptoms of fish bubble disease are bulging eyes and bubbles on the body surface. With the development of bubble disease, symptoms such as bleeding in the gill, head and fins also occur. Fish with bubble disease often exhibit abnormal behavior in water, such as loss of balance, inability to swim upstream, and jumping out of the TDG supersaturation water surface in all directions. Bubble disease will threaten the survival of fish and even cause death in severe cases. For example, during the dam discharge in 2014, the discharge of Xiluodu Hydropower Station caused the death of more than 40 tons of fish in the downstream Xiangjiaba reservoir area due to TDG supersaturation.

[0004] Studies have shown that the severity of bubble disease in fish of different species and different ages under TDG supersaturation stress often differs. In order to effectively evaluate the influence of TDG supersaturation caused by dam discharge on fish bubble disease, an index for evaluating the severity of fish bubble disease is needed. At present, scholars in this field have preliminarily described the phenomenon of fish bubble disease under TDG supersaturation stress, but only qualitative description of symptoms is made, and there is no clear index to quantitatively describe the severity of fish bubble disease. SUMMARY

[0005] The present application aims at the technical vacancy of quantitatively evaluating the severity of fish bubble disease in the prior art, and provides a method for quantitatively evaluating the severity of fish bubble disease under TDG supersaturation stress.

[0006] The method for quantitatively evaluating the severity of fish bubble disease under TDG supersaturation stress provided by the present application has the following steps:

[0007] S1, placing fish under supersaturation stress under a microscope to observe the amount of attached bubbles and bleeding symptoms of tail fin, anal fin, ventral fin, pectoral fin and dorsal fin respectively, and taking photos of each fin;

[0008] S2, according to the photos of each fin, measuring the total area S (cm 2 ), bubble coverage area S1 (cm 2 ), and bleeding area S2 (cm 2 ) of each fin; and calculating the bubble amount severity α1 and bleeding symptom severity α2 of each fin;

[0009]

[0010]

[0011] S3, scoring according to the size of α1 and α2:

[0012] Bubble amount score: when each fin has no bubble, i.e. α1 = 0, score 0; when the bubble coverage area is less than 50% of the total area of the fin, i.e. α1 < 50%, score 1, defined as a small amount of bubbles; when the bubble coverage area is greater than or equal to 50% of the total area of the fin, i.e. α1 ≥ 50%, score 2, defined as a large amount of bubbles.

[0013] Bleeding symptom score: when each fin has no bleeding, i.e. α2 = 0, score 0; when the bleeding coverage area is less than 50% of the total area of the fin, i.e. α2 < 50%, score 1, defined as a small amount of bleeding; when the bleeding coverage area is greater than or equal to 50% of the total area of the fin, i.e. α2 ≥ 50%, score 2, defined as a large amount of bleeding.

[0014] Calculate the score t of each fin, t = bubble amount score + bleeding symptom score.

[0015] S4, calculate the comprehensive score T of the fish according to the score of each fin, and the calculation formula is as follows:

[0016]

[0017] In the formula, t1-t5 represent the scores of the tail fin, anal fin, ventral fin, pectoral fin and dorsal fin of the fish respectively;

[0018] S5, determine the severity of fish bubble disease under TDG supersaturation stress, and the determination standard is as follows:

[0019] The comprehensive score of 0-1 is determined as level I, and the stress degree is slight.

[0020] The comprehensive score of 1-2 is determined as level II, and the stress degree is relatively slight.

[0021] The comprehensive score of 2-3 is determined as level III, and the stress degree is relatively serious.

[0022] The comprehensive score of 3-4 is determined as level IV, and the stress degree is serious.

[0023] In the above method, the fish to be analyzed is obtained by the following ways: (1) obtained from downstream of dam during dam flood discharge; (2) obtained in eutrophicated water body; (3) obtained in normal water body and then placed in TDG supersaturated water body for cultivation, so that the fish is stressed by TDG supersaturation, and the fish is taken out for observation after several days.

[0024] In order to further improve the accuracy, in steps S1-S4, a plurality of fish can be taken for analysis one by one, and the comprehensive score T of each fish is calculated; then the average comprehensive score of all fish is calculated; and then the judgment is made according to the judgment standard of step S5, so that the severity of bubble disease of a fish in the TDG environment is obtained.

[0025] Preferably, in step S1, a variable focus microscope is used for observation.

[0026] Preferably, in step S2, CAD software is used to analyze the photos of each fin to obtain the total area S, the bubble coverage area S1 and the bleeding area S2 of each fin.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] (1) The present application first proposes a quantitative evaluation method for the severity of bubble disease of fish under TDG supersaturation stress, scores the amount of bubbles attached to each fin of the fish and the severity of bleeding symptoms, calculates the comprehensive score of the fish, and determines the degree of TDG supersaturation stress of the fish according to the comprehensive score. The evaluation of the severity of bubble disease of fish is more clear and accurate, and the standard is more unified. The present application provides scientific guidance for better understanding the influence of fish in TDG supersaturated water.

[0029] (2) The present application fills the gap of the technical system for quantitatively evaluating the severity of bubble disease of fish, and enriches the theoretical basis for the evaluation of the influence of total dissolved gas supersaturation of water conservancy projects on fish.

[0030] (3) The materials required for the method of the present application are only fish stressed by TDG, and a microscope, which are simple, easy to obtain, low in cost, easy to operate, and have strong practicability.

[0031] Other advantages, objects, and features of the application will be apparent from the following specification and appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Figure 1 is a diagram showing the symptoms of bubble disease in fish under a microscope.

[0033] Figure 2 Figure 2 is a diagram showing the scoring of the degree of bubble disease in each fin. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present application will be described below in conjunction with the accompanying drawings, in which it should be understood that the preferred embodiments described herein are intended to illustrate and explain the present application, and are not intended to limit the present application.

[0035] The method for obtaining fish under TDG supersaturation stress in this embodiment is as follows: after being obtained in normal water, the fish is placed in TDG supersaturated water (downstream of dam during dam flood discharge) for cultivation, so that the fish is subjected to TDG supersaturation stress, and the fish is taken out for observation after several days.

[0036] This embodiment is carried out on the upper reaches of the Rongjiang River in Jiangkou Town, Guiping City, Guigang City, Guangxi Zhuang Autonomous Region.

[0037] In this embodiment, adult grass carp is selected as the test object.

[0038] The water temperature of the Rongjiang River in this embodiment ranges from 25.4 to 27.6°C; the dissolved oxygen ranges from 7.06 to 9.04 mg / L; and the TDG ranges from 115% to 123%.

[0039] The specific operation steps of the entire test are as follows:

[0040] (1) 10 normal growing adult grass carps are obtained in a local fish farmer's farm as test fish;

[0041] (2) The 10 test fish are evenly divided into 5 groups and placed in 5 fishing nets, and the fishing net numbers are group A, group B, group C, group D, and group E, two fish in each group, and the fish are sequentially numbered as fish 1, fish 2, fish 3, fish 4, fish 5, fish 6, fish 7, fish 8, fish 9, and fish 10. All the fish are placed in the surface layer of the Rongjiang River for cultivation, and the test starts, which is recorded as the 0th day of TDG supersaturation stress.

[0042] (3) The data of water temperature, dissolved oxygen, and TDG are continuously monitored during the test, and the readings are recorded.

[0043] (4) On the 10th day of TDG supersaturation stress, 10 test fish were taken out and placed under a microscope to observe the amount of bubbles attached to each fin (caudal fin, anal fin, ventral fin, pectoral fin and dorsal fin) and the severity of hemorrhagic symptoms. The photos of each fin taken by the microscope were put into CAD software to measure the bubble coverage area (S1), the hemorrhagic area (S2) and the total area of each fin (S). The degree of bubble disease of fish was quantitatively evaluated according to the calculation formula of the amount of bubbles and the severity of hemorrhagic symptoms α and the comprehensive score T described in the technical solution. Figure 1 is an example of scoring the degree of bubble disease of each fin. The bubble disease symptoms of the test fish are as shown in Figure 2 and the scoring of each fish is shown in Table 1.

[0044] Table 1 shows the symptoms and scoring of each fin of the test fish

[0045]

[0046] According to the technical solution, when α1 or α2 is equal to 0, the score is 0; when α1 or α2 is less than 50%, the score is 1; when α1 or α2 is greater than 50%, the score is 2. For a certain fin, the score of the fin is equal to the score of the bubble plus the score of the hemorrhagic symptom, and the comprehensive score is equal to the average of the scores of each fin.

[0047] Taking fish 1 in group A as an example: in the caudal fin, α1 = 36% < 50%, the score is 1, and α2 = 62% > 50%, the score is 2, so the score of the caudal fin is 3; in the anal fin, α1 = 12% < 50%, the score is 1, and α2 = 15% < 50%, the score is 1, so the score of the anal fin is 2; in the ventral fin, α1 = 10% < 50%, the score is 1, and α2 = 0, the score is 0, so the score of the ventral fin is 1; in the pectoral fin, α1 = 22% < 50%, the score is 1, and α2 = 0, the score is 0, so the score of the pectoral fin is 1; in the dorsal fin, α1 = 26% < 50%, the score is 1, and α2 = 0, the score is 0, so the score of the dorsal fin is 1. The comprehensive score T is equal to the average of the scores of each fin, i.e. T = (3 + 2 + 1 + 1 + 1) / 5 = 1.6, i.e. the comprehensive score of fish 1 in group A is 1.6.

[0048] Table 1 shows that the scores of the remaining 9 test fish are in the range of 1-2, and the average comprehensive score of the 10 test fish is 1.38. According to the standard for determining the degree of bubble disease of fish under TDG supersaturation stress in the technical solution, the TDG level will cause grass carp to suffer from bubble disease. The degree of bubble disease of the test fish under TDG supersaturation stress is grade II, and the stress degree is relatively mild.

[0049] (6) The 10 test fish observed were put back into the Xunjiang River, and the test was completed.

[0050] In summary, the present application provides a method for quantitatively evaluating the degree of bubble disease of fish under TDG supersaturation stress, which is achieved by scoring the severity of bubble disease symptoms of fish, such as scoring the severity of bubbles and bleeding symptoms attached to each fin of fish. Through this method, the severity of bubble disease of each fin of fish can be expressed by a unified quantitative evaluation standard, and the severity of bubble disease of the fish can be obtained by comprehensively scoring each fin, which enriches the evaluation system of the influence of dissolved gas supersaturation in water conservancy projects on fish. It provides scientific guidance for better understanding the influence of fish in TDG supersaturated water.

[0051] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A method for quantitatively evaluating the degree of bubble disease in fish under TDG supersaturation stress, characterized by, The steps are as follows: S1, place the fish under saturated stress under a microscope to observe the amount of attached bubbles and bleeding symptoms of the tail fin, anal fin, ventral fin, pectoral fin and dorsal fin respectively, and take photos of each fin; S2, according to the photos of each fin, the total area S of each fin, the bubble coverage area S1, the bleeding area S2 are measured; the bubble amount severity of each fin is calculated and the bleeding symptom severity ; S3. The method of S2, wherein the score is based on a size of the at least one object. and the size of the at least one object. Bubble amount score: when = 0, score 0; when < 50%, score 1; ≥ 50%, score 2; Bleeding symptom score: Score 0 when = 0; Score 1 when < 50%; Score 2 when ≥ 50%. Calculate the score t of each fin, t = bubble amount score + bleeding symptom score; S4, a composite score for the fish is calculated from the individual fin scores T The formula is as follows: wherein Score for tail fin, anal fin, ventral fin, pectoral fin and dorsal fin of fish, respectively;​ S5, determine the degree of bubble disease of fish under TDG supersaturation stress, and the determination criteria are as follows: The comprehensive score is 0-1, which is determined as grade I, and the stress degree is slight; The comprehensive score is 1-2, which is determined as grade II, and the stress degree is slightly lighter; The comprehensive score is 2-3, which is determined as grade III, and the stress degree is relatively serious; The comprehensive score is 3-4, which is determined as grade IV, and the stress degree is serious.

2. The method of claim 1, wherein the degree of gas bubble disease in fish under TDG supersaturation stress is quantitatively evaluated by the following equation: Degree of gas bubble disease = (a + b) / 2 wherein a is the number of fish with gas bubble disease in the test group, and b is the number of fish with gas bubble disease in the control group. The fish to be analyzed is obtained by the following ways: (1) obtained from the downstream of the dam during dam flood discharge; (2) obtained in eutrophic water body; (3) obtained in normal water body and then placed in TDG supersaturated water body for breeding, so as to make it suffer from TDG supersaturation stress, and then taken out for observation after several days.

3. The method of claim 2, wherein the degree of gas bubble disease in fish under TDG supersaturation stress is quantitatively evaluated by the following equation: Degree of gas bubble disease = (a + b) / 2 wherein a is the number of fish with gas bubble disease in the test group, and b is the number of fish with gas bubble disease in the control group. In steps S1-S4, a plurality of fish are taken and analyzed one by one, and a comprehensive score of each fish is calculated T； Then the average comprehensive score of all fish is calculated; According to the determination criteria of step S5, the severity of bubble disease of a certain fish species in the TDG environment is determined.

4. The quantitative assessment method for the severity of gas bubble disease in fish under TDG oversaturation stress as described in claim 1, characterized in that, A variable focus microscope is used for observation.

5. The quantitative assessment method for the severity of gas bubble disease in fish under TDG oversaturation stress as described in claim 1, characterized in that, The photos of each fin are analyzed by CAD software to obtain the total area S, bubble coverage area S1 and bleeding area S2 of each fin.

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