Green algae control method for aquaculture rafts based on self-decomposition habitat creation

Abstract

The present invention discloses a method for controlling the biomass of green algae on laver rafts based on the creation of a self-sabotaging habitat. The method mainly adopts the life history characteristics of the green algae on the laver rafts, selects the early stages of rapid growth of the green algae population in autumn and spring on the laver cultivation rafts, i.e., late September to early November and February to early April, and wraps the cables and supports with PE wrapping film to form a high-temperature and hypoxic environment within the film, thereby promoting the fermentation of anaerobic microorganisms and causing the green algae to die within 24 to 48 hours, thereby achieving the control of the green algae biomass on the laver rafts.

Description

Technical Field

[0001] The invention relates to a method for inducing the natural death and decay of green algae by creating an anaerobic environment, thereby controlling the biomass of green algae on a laver cultivation raft. Background Art

[0002] my country is a major laver-farming nation, with laver cultivation occurring from Liaoning in the north to Guangdong in the south. Green algae contamination has long been a major problem for laver producers. During the laver seedling cultivation period, the presence of large amounts of green algae on the net curtains can severely inhibit the growth of the laver seedlings, leading to reduced or even total yields. During the laver harvest, the widespread distribution of green algae on the laver rafts can degrade the quality of the product. In the later stages of laver cultivation, inappropriate handling of green algae on the rafts has led to outbreaks of Enteromorpha in the Yellow Sea.

[0003] Currently, the methods for treating green algae on laver aquaculture rafts include chemical control, biological control, and physical control. Among them, the chemical control method mainly uses algaecides such as hydrochloric acid and sodium hypochlorite to remove green algae from laver nets and rafts. The specific methods are shown in Chinese patents CN 101822271A and CN 102550388A. Although they are highly efficient, hydrochloric acid and sodium hypochlorite are both highly corrosive, posing safety hazards to workers. Large-scale use is prone to environmental risks such as sea acidification. The biological control method is to sow laver seedlings on the aquaculture cables in advance and use the growth of laver to inhibit the attachment of green algae to the aquaculture ropes (Fu, ML, et al., 2022. Controlling the main source of green tides in the Yellow Sea through the method of biological competition. Mar. Pollut. Bull. 177, 113561.). However, this method is greatly affected by the water temperature in the sea area, the control effect is unstable, and it increases the cost of seedling cultivation. Physical prevention and control is to prevent green algae from adhering to the surface of the cable by changing the chemical properties of the cable. Chinese patent CN 104957025B discloses a method for preventing green algae from adhering by applying anti-adhesion paint, but the effectiveness of this method is short, only about 3 months, and the dosage is large and the cost is high, which is not conducive to promotion. Xia (Xia, ZY, et al., 2022. A review of physical, chemical, and biological green tide prevention methods in the Southern Yellow Sea. Marine Pollution Bulletin 180, 113772) and others reported that the attachment of green algae was inhibited by using polyethylene cable sleeves. The effect was good in the short term, but under the erosion of sunlight and sediment, grooves were easily formed on the surface of the sleeve, which was the attachment of green algae, thereby losing the prevention and control effect. In addition, the cost of the sleeve is high and it significantly increases the weight of the cable, which is not conducive to promotion. Summary of the Invention

[0004] In response to the above problems, the present invention provides a method for controlling green algae on laver cultivation rafts based on the creation of a self-decomposing habitat. It is a simple and efficient technology for controlling green algae on laver rafts based on the creation of an anaerobic environment. The control of the green algae biomass on the laver raft is achieved by inducing the natural death and decay of the green algae.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for controlling green algae on laver cultivation rafts based on the creation of a self-decomposing habitat is used. During the laver cultivation cycle, the laver cultivation rafts are wrapped with stretch wrap film to create a high-temperature anaerobic environment, forming an algae self-decomposition habitat, inducing the natural death and decay of green algae, thereby removing the green algae growing on the rafts.

[0007] Furthermore, the green algae may be Enteromorpha, Enteromorpha planulata, Enteromorpha siphonata, Enteromorpha circumflexa, etc.

[0008] Furthermore, the laver cultivation period is from September to May of the following year.

[0009] Furthermore, the early stages of rapid growth of autumn green algae and spring green algae populations on laver culture rafts were selected, namely late September to early November and February to early April.

[0010] Furthermore, the parts of the laver cultivation raft for removing green algae include the floater, the stake cable, the bamboo support rod and the support frame of the laver cultivation raft.

[0011] Furthermore, the stretch wrapping film is a polyethylene (PE) colorless wrapping film with a thickness of 0.013 to 0.02 mm and a width of 10 to 20 cm.

[0012] Furthermore, the method of wrapping the laver cultivation raft frame with stretch wrap film is: fix it on one end of the cable (floating cable, stake cable) or bracket (bamboo support rod and support frame), wrap it in sequence, and the overlapping part is half of the film width. During the wrapping process, the stretch wrap film is stretched as much as possible, and the cable is tightly wrapped using the retraction force of the stretch wrap film.

[0013] The invention mainly relies on the life history characteristics of green algae growing on the laver raft, selects the early stage of rapid growth of green algae populations in autumn and spring on the laver cultivation raft, wraps the cable and the bracket with PE wrapping film, forms a high-temperature and oxygen-deficient environment in the film, promotes the fermentation of anaerobic microorganisms, causes the green algae to die within 24 to 48 hours, and realizes the control of the green algae biomass on the laver raft.

[0014] Beneficial effects of the present invention:

[0015] The present invention can be implemented at any time during the laver cultivation cycle. In addition to inducing the death of the original green algae on the cable, the smooth surface of the stretch wrap film can also be used to create a dry and dehydrated environment, effectively inhibiting the attachment of new green algae during the laver cultivation period. The present invention has the advantages of simple operation, low cost of use (the cost of removing the raft frame per mu is less than 20 yuan), and long validity period. It can avoid the use of chemical reagents and will not cause adverse effects on laver and the environment. If the present invention can be widely promoted in various laver cultivation areas, it can not only effectively reduce the green algae pollution in the laver cultivation process and improve the quality of cultivated laver, but also prevent and control the outbreak of the green tide of Enteromorpha in the Yellow Sea from the root.

[0016] Figures in the specification

[0017] Figure 1 These are the results of the green algae prevention and control test on the laver cultivation raft cables in Example 2, which was started on April 11, 2023. The left picture shows the untreated cable, and the right picture shows the treated cable. DETAILED DESCRIPTION

[0018] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0019] The invention will be further described below with reference to the embodiments.

[0020] Example 1

[0021] This embodiment uses the removal of green algae from rafts in the laver cultivation area in the coastal waters of Dalian, Liaoning Province in autumn as the material to further describe the present invention in detail.

[0022] 1. In the Dengsha River waters of Jinzhou, Dalian, laver farming adopts a pole-inserted or fully floating farming model. Its raft frame structure is mainly composed of net curtains, bamboo support poles, floating cables, and stake cables. From September to October every year, green algae on the raft frame release spores and attach to the net curtains, which has a very adverse impact on laver seedling cultivation.

[0023] 2. Before the seedling nets are lowered to the sea in mid-September each year, a significant amount of green algae, such as Enteromorpha fringei, forms on the cables of the rafts. In late September 2021, a green algae removal experiment was conducted on three 10-meter-long floating cables on the laver cultivation rafts. First, the rafts were supported by a boat. On board, the cables were wrapped with 0.02mm-thick, 10cm-wide PE wrap, with the overlap being half the width of the wrap. The wrapped cables were immediately immersed in seawater. Samples were collected daily at sea and observed in the laboratory using an inverted fluorescence microscope.

[0024] 3. On the second day of the experiment, naked eye observation showed no obvious change in the color of the algae; microscopic observation showed that the fluorescence of the vast majority of algae changed from bright red to pink, and the fluorescence intensity decreased, indicating that the activity of the algae was inhibited; on the third day, naked eye observation showed that most algae were yellow-green, while microscopic observation showed that almost all algae emitted dark red fluorescence, indicating that these algae were dead. On the fourth day, naked eye observation showed that the color of almost all algae turned yellow-green or dark green, and even bacterial film appeared, indicating that the algae had begun to rot.

[0025] 4. After two months of sea trials, no green algae survived inside the cables wrapped with PE wrapping film, and only a small amount of green algae adhered to the outer surface of the film. In contrast, the cables in the untreated control group were completely covered with green algae.

[0026] Example 2

[0027] This embodiment uses the removal of green algae from rafts in the laver cultivation area in the coastal waters of Qidong, Jiangsu Province in winter and spring as materials to further describe the present invention in detail.

[0028] Due to the shallow waters and periodic drying out in the coastal waters of Qidong, Jiangsu Province, a semi-floating system is commonly used for the cultivation and cultivation of Porphyra yezoensis. The raft structure primarily consists of a net curtain, bamboo support frame, floater cables, and drop cables, which serve as the primary substrate for the green algae.

[0029] On February 4, 2023, algae removal operations were conducted on cables used for laver cultivation rafts in the Qidong waters of Nantong, Jiangsu Province. Conducted during low tide, cables already covered with algae were used as test materials. The cables were wrapped with 0.013mm thick PE stretch film, with widths of 10 and 20cm, respectively, with an overlap of half the film width. The film was stretched as much as possible during the wrapping process, using the film's retractive force to tightly wrap the cables.

[0030] 3. During the recovery of the laver rafts on April 11, 2023, it was observed that although holes (less than 0.5 cm in diameter) appeared on the PE wrapping film of some cables after two wear and tear by the laver-collecting boats, the overall structure of the wrapping film remained intact. There was no green algae on the cables wrapped in the PE wrapping film, and no green algae attached to the outer surface of the PE wrapping film. However, green algae were widely distributed on the surrounding untreated cables (see Figure 1 ).

[0031] Anyone skilled in the art will be able to utilize the above-disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or to modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention that do not depart from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for controlling green algae in laver cultivation rafts based on self-decomposing habitats, characterized in that: During the laver cultivation cycle, the laver cultivation rafts are wrapped with stretch wrap to create an algae self-decomposition habitat and remove green algae growing on the rafts; The stretch wrap film is a polyethylene colorless wrap film; The parts for removing green algae on the laver cultivation raft frame include a floating cable, a cleat cable, a bamboo supporting rod and a supporting frame of the laver raft frame.

2. The method according to claim 1, characterized in that The laver cultivation period is from September to May of the following year.

3. The method according to claim 1, characterized in that The stretch wrap film has a thickness of 0.013 to 0.02 mm and a width of 10 to 20 cm.

4. The method according to claim 1, wherein The method of wrapping the laver culture raft with stretch film is as follows: fix it at one end of the cable or bracket, wrap it in sequence, and control the overlapping part to half of the film width. During the wrapping process, the stretch film is stretched and the cable is wrapped by using the retraction force of the stretch film.

5. The method according to claim 1, wherein The green algae is Enteromorpha spp., Enteromorpha spp. flat, Enteromorpha spp. or Enteromorpha spp. marginale.

6. The method according to claim 1, wherein Choose late September to early November and February to early April.

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