JP6704562B2 - Method of inducing light-escape behavior of red tide-caused rafido algae - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for inducing a light-escape behavior of red tide-causing rafido algae. More specifically, the present invention relates to a method for inducing a light-escape action by irradiating or removing light having a wavelength in a certain region with respect to red tide-causing rafido algae. The present invention further relates to a method, device, etc. for reducing the damage of red tide using the method.

Traditionally, damage caused by the occurrence of red tide has been a problem in the seafood aquaculture industry and the like. In recent years, harmful red tides caused by flagellates have frequently occurred in coastal areas of western Japan, and the total damage to the aquaculture industry was 3.3 billion yen and 5.5 billion yen in the Yatsushiro Sea in 2009 and 2010, respectively, and Bungo Channel in 2012. It is reported to be 1.5 billion yen.

Various techniques have been devised for many years to prevent red tide damage. For example, as a red tide control method for harmful flagellates, chemical substances (hydrogen peroxide, magnesium hydroxide, etc.) Methods have been devised.
As one of such technologies, an algaecide containing an amine as an active ingredient, which is effective against Chattonella antiqua, which is a kind of plankton that causes harmful red tide, has been developed. (See Patent Document 1).
However, spraying these chemicals and organisms requires enormous costs every time a red tide occurs, its application range is narrow, and the burden on the environment and organisms other than the organisms causing the red tide is large. Therefore, it is the current situation that it has not been put to practical use.

As a technology that is generally put into practical use, there is a method to improve red tide resistance by stopping food before the red tide occurs, but a method to predict the red tide occurrence at a high rate has not been established, and damage to fish bodies and delays in shipping etc. There are weaknesses such as having a great adverse effect on the management of fishermen.
In addition, a method has also been devised to reduce the damage caused by red tide by reducing the frequency of contact between organisms that cause red tide and cultured seafood, such as by surrounding the cage with a vinyl sheet, etc. Even if the red tide flowing from the horizontal direction can be prevented, it cannot cope with the red tide rising due to vertical movements around the day, and it cannot be said to have a sufficient effect for practical use.

Further, Patent Document 2 discloses a method of suppressing the growth of algae that causes red tide by irradiating light with a wavelength in a specific region. In this technology, by irradiating light with a specific wavelength of 550 to 720 nm, Heterocapsa circularisquama, Karenia mikimotoi, Cockrodinium polychrycoides, Cochlodich It has been confirmed that the growth of Heterosigma akashiwo and the like was suppressed. With this technology, it is possible to control the growth of algae by suppressing the growth of harmful algae that cause red tide by irradiating light, or by promoting the growth of useful algae, but it is already in place. It is not possible to remove the harmful algae that are being produced. Therefore, the growth of algae that cause red tide can be controlled in a closed space such as a small-scale experimental system in a room, but the algae that cause red tide can constantly flow in, and occurs in vast scales such as lakes and seas. Red tide is not a sufficient technology to prevent the increase in damage and cannot be put to practical use.

As described above, various red tide control techniques have been devised for many years, but none have been put to practical use and capable of significantly reducing the damage of red tide. Therefore, even now, there is an urgent need to construct epoch-making measures that can suppress damage caused by the occurrence of red tide and to develop eradication technology.

JP-A-7-242508 JP, 2007-68419, A

The present invention is also effective in reducing the damage of red tides that occur in vast scales such as lakes and seas, and provides a method of an epoch-making red tide occurrence prevention method with less load on living organisms and the environment. To do.

As a result of intensive studies to solve the above problems, the present inventors have found that many harmful red tide-causing algae perform flagella movements and swim, and that the depth of the layer localized during the day changes depending on the light environment outdoors. It was found by investigation.
Based on the research results of the present inventors, it was found that the light escape behavior of the red tide-causing rafidoalgae can be induced by irradiating light with a wavelength in a certain region, and the present invention has been completed. In the present invention, further, by inducing the light-escape behavior of the red tide-causing rafido algae, removing these algae from places where it is desired to prevent the occurrence of red tides such as aquaculture cages, or to prevent the inflow from the outside. It is possible to reduce the damage of the red tide.
Such a method of the present invention is capable of inducing the light-escape behavior of red tide-caused rafidoalgae by installing optical components such as irradiation and filters for a short period of time, and since it can be applied in aquaculture cages, It is also a practical method for reducing red tide damage, as it has less impact on other organisms and the environment.

That is, the present invention relates to the following methods (1) to (10) for inducing the light-escape behavior of the red tide-causing rafido algae.
(1) A method of inducing a light-escape action of a red tide-caused raphidid algae by irradiating with light having a wavelength of 320 nm to 440 nm (UV-B to blue region) and/or 640 nm to 680 nm (red region).
(2) The method according to (1) above, which further cuts off light having a wavelength of 480 to 560 nm (green region) to induce a light-escape action of the red tide-caused rafidoalgae.
(3) The method for inducing the light-escape behavior of the red tide-caused raphidid alga according to (1) or (2) above, wherein the light irradiation is from the upward direction and/or the lateral direction.
(4) The method according to any one of (1) to (3) above, which reduces the damage of red tide by inducing the light-escape behavior of the red tide-causing rafidoalgae.
(5) The method according to any one of (1) to (4) above, wherein the red tide-causing rafido alga is Chattonella antique.
(6) A device for inducing a light-escape action of red tide-caused raphidid algae, which comprises a means for irradiating light with a wavelength of 320 nm to 440 nm (UV-B to blue region) and/or 640 nm to 680 nm (red region).
(7) The device according to (6) above, which further comprises means for cutting off light having a wavelength of 480 to 560 nm (green region), and which induces the light-escape behavior of the red tide-causing Rafido algae.
(8) The device for inducing the light-escape behavior of the red tide-caused rafidophyte according to (6) or (7), wherein the light irradiation is from the upward and/or the lateral direction.
(9) The device according to any one of (6) to (8) above, which comprises a cage or seawater filtration mechanism or means for setting in the vicinity thereof, for reducing red tide damage.
(10) The apparatus according to any of (6) to (9) above, wherein the red tide-causing rafido alga is Chattonella antiqua.

By providing a method of inducing the light-escape behavior of the red tide-causing rafido algae of the present invention, it is effective in reducing the damage of the red tide, and is an epoch-making red tide occurrence prevention measure that is small and has a small load on living organisms and the environment. Can be provided. Further, according to the present invention, by irradiating light of a specific wavelength or by installing an optical component such as a filter, it is possible to provide a device for inducing the light-escape action of the red tide-causing rafidoalgae and reducing the damage of the red tide. It will be possible.

It is the figure which showed the examination result of the action spectrum of light escape behavior (Example 1). It is the figure which showed the examination result of the light intensity and irradiation time which induce a light escape behavior (Example 2). It is a figure showing the examination result of the inhibitory effect of light escape behavior by green light (Example 3).

The “method of inducing the light-escape behavior of the red tide-causing rafidoalgae” of the present invention is to irradiate light having a wavelength of 320 nm to 440 nm (UV-B to blue region) and/or 640 nm to 680 nm (red region), or green. Any method can be used as long as it can induce the light-escape behavior of the red tide-causing rafidoalgae by removing only the region (around 520 nm).
According to such a method, the cultured cage containing the red tide-causing rafido algae is irradiated with light having a wavelength of 320 nm to 440 nm (UV-B to blue region) or a wavelength of 640 nm to 680 nm (red region). Alternatively, both of these lights may be irradiated. Further, only the green region (near 520 nm) may be removed.

The "light escape behavior" in the present invention means that the red tide-causing rafidoalgae move downward or in the direction of low light intensity when irradiated with light. For example, when the light of the above wavelength is irradiated from the upper side to the lower side, the red tide-causing rafido algae moves downward.

In the “method of inducing the light-escape behavior of red tide-causing rafidoalgae” of the present invention, it is preferable to further prevent irradiation with light having a wavelength of around 520 nm (green region).
As a method of cutting such green light, various optical parts such as a bandpass filter are used.

In the "method of inducing the light-escape behavior of red tide-causing rafido algae" of the present invention, the environment in which the red tide-causing rafido algae is present, the specific direction from the direction opposite to the direction in which the red tide-causing rafido algae is desired to run It is preferable to irradiate light having a wavelength.
As the direction of such light irradiation, it is effective to irradiate from the upper direction or the left-right direction, and the irradiation from the upper direction and the irradiation from the left-right direction are combined at the same time or alternately, You may irradiate with a fixed rhythm.

The "method of inducing the light-escape behavior of the red tide-caused rafido algae" of the present invention is a method of artificially changing the light environment to control the behavior of living things, such as a fish-collecting fishing method (saury fishing, squid fishing, etc.). Since it is a method similar to the method actually used in the field of fisheries, it is a practical method even when used to reduce red tide damage, etc., because it has less load on other organisms and the environment. I can say.
In particular, the light in the blue region to be irradiated in the present invention is the light that is most easily transmitted into seawater, and is therefore effective in adaptation to seawater and the like.

The “red tide-causing rafido algae” in the present invention refers to algae having flagella that cause red tide. Among the red tide-causing raphidophytes, as the algae that induce the light-escape behavior of the present invention, particularly the rafidoalga such as Chattonella antica and Heterosigma akashiwo are preferable.

The "method of reducing damage of red tide" of the present invention is an "environment where red tide-causing rafidoalgae exists" by "a method of inducing a light-escape action of red tide-causing rafidoalgae" by irradiating with light of the above specific wavelength. Any method that can reduce the damage of the red tide by reducing these ratios in
This “method of inducing light-escape behavior of red tide-causing rafido algae” alone may be used, or it may be combined with other conventionally known methods for reducing damage of red tide.

The “device for inducing the light-escape action of red tide-causing rafidoalgae” of the present invention is irradiation with light having a wavelength of 320 nm to 440 nm (UV-B to blue region) and/or 640 nm to 680 nm (red region) of the present invention. Any device capable of performing the above is preferable, and a device including these light sources or a device including them is preferable.
Further, it is preferable that the device has an optical filter or the like capable of cutting off light having a wavelength near 520 nm (green region).
These devices are, for example, devices that can be set in cages for cultivating cultured fish, or from the outlet in the seawater filtration process (water tank, etc.) at seedling preservation facilities and experimental facilities that use seawater drawn from the coast. It is preferable that the device is capable of preventing invasion of harmful red tide algae.

Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention, but the present invention is not limited thereto.

Unless otherwise specified, in the examples of the present invention, the red tide-causing rafidoalgae prepared as described below were used and tested and analyzed under the following conditions.
1. Red tide-causing rafido algae As red tide-causing rafido algae, subculture was performed at 25° C., 300 μmolm ⁻² s ⁻¹ (white fluorescent lamp), 12 hours light: 12 hours dark/dark cycle (6:00 to 18:00), The rafido alga, Chattonella antiqua, which causes harmful red tide, was used.
On the day before the test, a fresh medium and a culture solution were mixed so that the cell density would be 5000 cells/mL, and the mixture was placed in a rectangular water tank (water depth 5 cm), and the light intensity in the light period was lowered to 20 μmolm ⁻² s ⁻¹ and cultured. After that, it was subjected to the test.

2. Test/Analysis Conditions The test was conducted from 8:30 to 15:00, which is the time zone when Shutnera Antica accumulates on the surface due to the daily vertical movement.
The swimming behavior of Chattonella Antica was observed with a CCD camera (CFW, Scion Corporation, Frederick, MD, USA) using infrared rays (850 nm) as observation light, and then Image J (http://rsb.info.nih.gov/ij). The cell density of the surface layer was quantified by performing image analysis using /).

[Example 1]
Examination of action spectrum of light-escape behavior By Okazaki large-scale spectrograph (Institute of Basic Biology), Shutnera Antica is irradiated with monochromatic light of 50 μmolm ⁻² s ⁻¹ from above in 40 nm interval of 320 to 680 nm, and swimming behavior Was observed over time. FIG. 1 shows the amount of decrease in cells in the surface layer 3 minutes after light irradiation as a relative value (%) at the start of irradiation.
As a result, as shown in FIG. 1, the cell density of the surface layer decreased with time under the monochromatic light of 320 to 480 nm and 640 to 680 nm. The amount of decrease in the surface layer cell density after 3 minutes reached the maximum value at 440 nm (blue light) and reached the minimum value at 520 nm (green light).
Therefore, from this result, in order to induce the light-escape behavior of Shutnera antica, monochromatic light irradiation of 320 nm to 440 nm (UV-B to blue region) or 640 nm to 680 nm (red region), particularly 440 nm (blue-violet) is performed. It was confirmed that it was useful.
It should be noted that this embodiment uses a large-scale spectrograph, and cannot be realized by an LED light source which is mixed with other wavelengths currently on the market.

[Example 2]
Examination of light intensity and irradiation time for inducing light-escape behavior Blue light (455 nm) having different light intensities (10, 30, 100, 150 μmolm ⁻² s ⁻¹ ) depending on the LED light source (Hololite HL01 type 455 nm, manufactured by Pi Photonics). ) Was irradiated to Shutnera and the swimming behavior was observed over time.
FIG. 2 shows the amount of cells reduced in the surface layer as a relative value (%) at the start of irradiation. As shown in FIG. 2, when blue light of 30 μmolm ⁻² s ⁻¹ , 100 μmolm ⁻² s ^−1, or 150 μmolm ⁻² s ⁻¹ was irradiated, the surface cell density decreased within 3 minutes after the start of irradiation. Was observed. When 100 μmolm ⁻² s ⁻¹ and 150 μmolm ⁻² s ⁻¹ of blue light was irradiated, the decrease amount of the surface layer cell density was saturated within 3 minutes after the start of irradiation, and even if the light intensity was increased, the density decreased. Was confirmed not to decrease.
Therefore, from this result, the threshold value of the light intensity of blue light (455 nm) required to induce the light-escape behavior of Shutnera antica within 3 minutes after the start of light irradiation is 10 to 30 μmolm ⁻² s ^−1. Was confirmed.

[Example 3]
The study of the inhibitory effect of light escape behavior by the green LED light source (ISL-150X150-HGB45, CCS Inc.), blue light chattonella (450nm, 50μmolm ^-2 s ^-1) or green light (525nm, 50μmolm ^-2 s ^-1 ) was irradiated alone. Further, blue light and green light having the same intensity were simultaneously irradiated, and the cell density of the surface layer of the cells was compared immediately before and 3 minutes after the irradiation.

FIG. 3 shows the amount of cells reduced in the surface layer as a relative value (%) at the start of irradiation. The dark condition in FIG. 3 indicates a condition where no light is applied. As shown in FIG. 3, a decrease in surface cell density was observed only when blue light was irradiated alone.
Therefore, from this result, when 50 μmolm ⁻² s ⁻¹ blue light (450 nm) is irradiated, when light in the green region (525 nm) is simultaneously irradiated with an intensity equal to or higher than that of blue light, the induction of light escape behavior of the Shutnera is induced. Therefore, it was suggested that light-escape behavior could be induced by cutting light in the green region from sunlight in the real environment.

By utilizing the method of inducing the light-escape behavior of the red tide-causing rafidoalgae that irradiates with light of a specific wavelength according to the present invention, it is possible to provide a device for reducing damage of the red tide.

Claims (10)

A method of inducing a light-escape behavior of a red tide-causing Rafidophyte by irradiating light with a wavelength of 320 nm to 440 nm (UV-B to blue region) and/or 640 nm to 680 nm (red region). The method according to claim 1, further comprising cutting off light having a wavelength of 480 to 560 nm (green region) to induce a light-escape behavior of the red tide-caused raphidid algae. The method for inducing light escape behavior of a red tide-causing Rafidophyceae according to claim 1 or 2, wherein the irradiation of light is from an upward direction and/or a lateral direction. A method for reducing the damage of red tide by inducing a light-escape behavior of a red tide-causing rafido alga by the method according to claim 1. The method according to claim 1 red tide causes rhaphidomonads algae is chattonella Antica (Chattonella antiqu a). A device for inducing a light-escape action of red tide-caused raphidid algae, which comprises means for irradiating light with a wavelength of 320 nm to 440 nm (UV-B to blue region) and/or 640 nm to 680 nm (red region). The device according to claim 6, further comprising means for cutting off light having a wavelength of 480 to 560 nm (green region), which induces the light-escape behavior of the red tide-caused rafidoalgae. The device for inducing light escape behavior of a red tide-caused raphidid alga according to claim 6 or 7, wherein the irradiation of light is from an upward direction and/or a lateral direction. The device according to any one of claims 6 to 8, which comprises a cage or a seawater filtration mechanism or means for setting in the vicinity thereof, for reducing damage of red tide. The device according to any one of claims 6 to 9, wherein the red tide-causing rafido alga is Chattonella antiqua.