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Abstract: In this test, cyanobacteria were fed high-temperature-tolerant branches (flea flea), and the survival of flea was observed under the conditions suitable for the survival of cyanobacteria, and whether the flea flea would feed and digest microcys. The results showed that after a certain period of incubation time, the digestive tract of Flea longifolia was filled with cyanobacteria. Observations can be seen: there are a large number of cyanobacterial cells in the posterior and anterior part of the midgut, which are cyanobacterial; there are already cyanobacteria scattered in the middle of the midgut that are not clumped, and some cyanobacteria have lost their intact cell morphology; the posterior end of the midgut still contains a large number of cyanobacteria, but they have not gathered into clumps, isolated into a single cyanobacterial cell, and a considerable part of the cyanobacterial cells have been incomplete; microcystis in the rectum has been better digested. Microcystinum has been shown to be ingested and digested by flea resonants.
Keywords: flea, microcystic algae, feeding digestion, preliminary observation
With the development of industrial and agricultural production, a large number of nitrogen and phosphorus are discharged into the water body, resulting in the increasingly serious phenomenon of eutrophication of the water body, and the eutrophication of the water body often leads to the crazy growth of algae to form a bloom, the water quality deteriorates, and the odor is produced. At the same time, dissolved oxygen in the water is reduced, biodiversity is reduced, and many algae can also produce toxins that are potentially harmful to animals and humans.
People have thought of many ways to treat cyanobacteria:
(1) Directional algae cultivation: At present, under the most suitable growth temperature conditions in nature, the growth rate of cyanobacteria is the fastest, followed by chlorella and grid algae. If in the early stage of breeding, the above two species of algae can be cultivated in the breeding pond as the dominant population of water bodies (directional cultivation), and the ratio with cyanobacteria reaches 100:1, so that the probability of cyanobacterial outbreaks will be greatly reduced.
(2) Eliminate eutrophication of water bodies: biological and chemical methods are used to effectively eliminate organic pollution, reduce organic pollution, and reduce the degree of eutrophication of water bodies to achieve indirect inhibition of the reproduction of cyanobacteria, usually every 10 days or so, the whole pond is sprinkled with 1 time of water treasure (Bacillus subtilis) and active black soil (sodium humate), the amount of which is 500 g and 1 000 g per mu, respectively. At the same time, domestic sewage is prevented from entering the pond to eliminate the impact of organophosphorus on water bodies.
(3) Adjust the ratio of nitrogen and phosphorus: when the cyanobacteria are bred in large quantities, the proportion of nitrogen and phosphorus in the water body is seriously imbalanced, and the general fish pond is missing inorganic phosphorus, and the proportion of nitrogen and phosphorus is changed by sprinkling inorganic phosphorus, accelerating the cultivation of beneficial algae such as green algae and diatoms to quickly grow into dominant algae to effectively inhibit the growth of cyanobacteria, the usual practice is to first use a strong oxidant to kill algae, and then the whole pond is sprinkled with sclerokinin 0.52g/m2 to improve the over-propagation of cyanobacteria.
(4) The use of microbial inhibition of algae: Bacillus lateral spore consumes macromolecular particles in the water body, absorbs too much nutrients, and competes with cyanobacteria for nutrition, while the extracellular substances secreted by Bacillus lateral spore can be directly in contact with cyanobacterial cells.
Usually in the cyanobacteria outbreak using the following measures to control: first of all, the whole pool sprinkled zeolite powder 14.99g / m2, so that it flocculation cyanobacteria; after 3-4h interval, the whole pool sprinkled with Bacillus algae lysophyllus (Bacillus lateral spore), the dosage of 500 g / mu, it is worth noting that the use of microorganisms must prevent the occurrence of hypoxia, so the weather is stuffy do not apply, when using microorganisms must start the aerator. But these methods have limited effect. Since the "biological manipulation" theory was first proposed in the 1970s, attention has been paid to the use of ways to regulate the structural composition of aquatic ecosystems to treat water bodies, and the method of controlling cyanobacterial blooms by directly regulating zooplankton populations has attracted special attention. At present, it has been studied that phylloids can feed on cyanobacteria, but their digestion and regeneration have not been studied. Through this experiment, it is hoped to explore the digestion and utilization level of cyanobacteria by branches and horns, and provide relevant references for the use of branches to control blooms and purify water quality.
1 Materials and methods
1.1 Test materials
Cyanobacteria: The cyanobacteria used in this test are Microcystis aeruginosa, and the algae species are provided by this laboratory.
Branches: The branches used in this test are Daphnia carinata, a genus of fleas, which are laboratory-grown high-temperature-resistant branches.
Drugs: NaNO3, K2HPO4, MgSO4·7H2O, CaCl2·7H2O, Na2CO3, citric acid, iron citrate, ampicillin, distilled water, agar, HB3O4, MnCl2·4H2O, ZnSO4N, NaMoO4, CuSO4·5H2O, Co(NO3)2·6H2O.
1.2 Test methods
Cyanobacteria medium BG-11 media: BG-11 medium formulation (microcystis): NaNO3 (1.5g), K2HPO4 (0.04g), MgSO4·7H2O (0.075g), CaCl2·7H2O (0.036g), Na2CO3 (0.02g), citric acid (0.006g), iron citrate (0.006g), *trace element solution (1 mL), ampicillin (final concentration: 50 μg/mL), Distilled water (100 ml), agar (20.0 g), 1 000 mL.
Table 1 Trace element solution A5 recipe
Test procedure: Microcystinum inoculated in the prepared BG-11 medium. Inoculated microcystis was placed in an artificial climate chamber and expanded at a temperature of 29.5 °C under 12 h of light per day, shaking twice a day. After 5 days of incubation, the color of the algae liquid became significantly thicker, and the concentration of cyanobacteria was high and high on microscopic examination. Inoculate the flea seeds in a plastic culture container, place them in a thermostatic tank, expand the culture at a temperature of 30 °C, and feed with feed powder. After both microcysticus and flea are successfully expanded and cultivated, microcystic flea is fed to fill the digestive tract of microcystis with microcystis. Every 5min, the flea is removed with a microscope to see if its digestive tract is filled with microcystis, and after 30min, the microcystis is filled with the digestive tract of the flea. After the digestive tract of the flea is filled with microcystinella, it is dissected under the anatomical microscope, the digestive tract is removed, and the degree of digestion of the anterior, middle and posterior intestinal flea in the gastrointestinal tract is observed and compared.
2 Test results
The entire digestive tract of the anatomical flea flea is shown in Figure 1, and the micrograph of the parts of the digestive tract of the flea flea and the morphology of the microcysts in them after enlargement of the corresponding parts (Figure 2).
Fig. 1 Gastrointestinal tract of flea longifolia (10×10)
Fig.1 Digestive tract of Daphnia carinata
Fig. 2 Flea esophagus and anterior segment of the midgut (10×10)
Fig.2 Esophaguses and midintestine of Daphnia carinata
As can be seen from Figure 3, there are a large number of microcystis in the esophagus and the anterior part of the midgut, and most of the cyanobacteria in the esophagus have been emptied due to the stimulation of the microanatomy of the flea, but it can be seen that there are still intact microcystis cells on the wall of the esophagus, and there are a large number of microcystic cells in the posterior and anterior part of the midgut, which are clumpy.
Fig. 3 Microcystis in the esophagus and anterior segment of the midgut (10×40)
Fig.3 Microcystis aeruginosa in the middle esophaguses and midintestine of Daphnia carinata
Fig. 4 Microcystis in the mid-intestinal segment (10×40)
Fig.3 Microcystis aeruginosa in the middle midintestine of Daphnia carinata
As can be seen from Figure 4, the mid-front microcystis morphology in the midgut has been dispersed in the middle of the midgut and has not been clumped, and some cyanobacteria have lost their intact cell morphology.
Fig. 5 Posterior midgut segment (10×10)
Fig.5 Back of midintestine of Daphnia carinata
Fig. 6 Microcystis in the posterior midgut segment (10×40)
Fig.6 Microcystis aeruginosa in the back of midintestine of Daphnia carinata
As can be seen from Figures 5 and 6, the posterior end of the midgut still contains a large number of cyanobacteria, but it has not gathered into clumps and is isolated into a single cyanobacterial cell. A considerable number of cyanobacterial cells are already incomplete.
Figure 7 Rectum (10×10)
Fig.7 Rectum of Daphnia carinata
Fig. 8 Microcystis in the rectum (10×40)
Fig.8 Microcystis aeruginosa in the rectum of Daphnia carinata
As can be seen from Figures 7 and 8, most of the microcystis in the rectum have completely lost their intact cell morphology. 3 Analytical discussion
3.1 Ediparability of flea microcystis
The flea used in this test is a high-temperature-resistant phylloid, which is in good condition under the temperature conditions suitable for the survival of microcystis. In the high concentration of microcystincula culture solution, the esophagus and intestines of flea are filled with microcystis, indicating that flea flea will feed on microcystis under experimental conditions.
3.2 Digestibility of flea microcystis on microcystis
This test shows that flea can feed microcystis, the digestion of each segment of the digestive tract is different, the middle and hindgus is the main part of digestion of microcystic algae, and the microcystic algae in the rectum have been well digested.
Source: Contemporary Aquatic Products, No. 4, 2014
Author: Rao Rui1 Gui Qingping1 Wang Guangjun2 Zheng Zonglin3 Li Zhifei1 Wang Haiying1
(1 Tongren Fishery Administration Office, Guizhou 554300, China; 1.Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510000, China; 2.Department of Fisheries, Rongchang Campus, Southwest University, Chongqing 402460, China)
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