JPH0428326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an artificial reef that can restore an ecosystem even in a polluted water area and can also purify water quality.

[Prior art] In recent years, the development of artificial reefs as a type of marine civil engineering has been active, and many proposals regarding this have been made (Utility Model Publication No. 58-155966, Japanese Patent Application Publication No. 60-12922,
JP-A-60-196133, JP-A-61-88831, JP-A-62
-32830, JP-A-63-207335, etc.). In many of these, in order to compensate for the decline in fish living in the ocean due to overfishing, structures that make up fish reefs are constructed by having a volumetric space that allows fish to enter the ocean, where habitat conditions are suitable according to the natural environment. It was designed for efficient fish farming.

[Problems to be Solved by the Invention] For example, the current situation is that on the downstream side of urban rivers, conditions are not suitable for fish to live due to water pollution caused by industrial wastewater, domestic wastewater, etc.
In particular, when the pollution is severe, the transparency of the river decreases, so sunlight does not reach near the riverbed, and plants cannot photosynthesize, resulting in poor plant growth and a lack of food for fish.

Therefore, even if a conventional fish reef structure with only living space elements for fish is placed in an environment where the habitat conditions for fish are not suitable,
It has been impossible to attract fish back to urban rivers.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and provide an artificial fish reef that can restore the ecosystem by increasing the feeding effect even in heavily polluted waters. There is a particular thing.

[Structure of the Invention] The present invention provides a fish nest structure that forms a fish nest space, and a light source that receives natural light or light from a light source from one end and emits the light from the other end supported by the fish nest structure. An artificial reef is constructed by installing fibers.

The other end of the optical fiber can be inserted into an adherent algae culture vessel placed in the fish nest space water area, or a phytoplankton culture vessel placed in a quiet area partitioned by the partition wall of the fish nest structure. It is preferable to form an incubator and emit light into the incubator.

[Effect] The biggest reason why it is not possible to secure food for fish in polluted waters is that light does not reach the water, and plants cannot actively photosynthesize.

In the present invention, an optical fiber is incorporated into the fish nest structure, and natural sunlight or other light source light incident from one end of the optical fiber is guided into the water by the optical fiber to promote photosynthesis in plants.

In other words, such polluted waters are rich in plant nutrients (such as nitrogen and phosphorus), so photosynthesis can be activated as long as light is supplied.

As a result of such promotion of photosynthesis, it is possible to promote the proliferation of attached algae or floating phytoplankton, increase the number of zooplankton that eat them, and secure the above plants or zooplankton as food for fish. can.

Furthermore, as a result of the propagation of photosynthetic plants, the food chain described above can be promoted, so that water quality can be purified by removing pollutants. Furthermore, as a result of photosynthesis by plants, oxygen can be secured in water and the amount of dissolved oxygen can be increased, ensuring habitat conditions for fish, and it is also possible to purify water by breeding aerobic microorganisms. .

In addition, in order to effectively grow adherent algae, insert the other end of the optical fiber inside a liquid-tight container.
By making the entire outer surface of the container a light emitting area, adherent algae can be grown on the outer surface of the container. In addition, since phytoplankton is floating, it is best to breed in an area separated from the fish nest space, and in such a case, it is sufficient to irradiate a culture vessel placed in a quiet area with light.

[Example] Hereinafter, an example in which the present invention is applied to an artificial reef placed on the bank of an urban river will be specifically described with reference to the drawings.

Fig. 1 is a schematic cross-sectional view showing a state in which an artificial reef, which is an example of the present invention, is placed on a riverbank, Fig. 2A,
B and C are a front view, a plan view, and a cross-sectional view of A of the same figure, respectively, of the fish nest structure.

In FIG. 1, a fish nest structure 10 is placed facing one bank 2 of a river 1 which has a flow from the front side to the back side of the drawing. This fish nest structure 10 includes a wall body 11 disposed in close contact with the seawall 2.
and a partition wall 12 arranged opposite to this wall body 11.
In order to form a fish nest space on the side of the partition wall 12 opposite to the seawall 2, a lower terrace 1 is provided which extends from the lower end of the partition wall 12 so as to come into contact with the riverbed.
4 and the lower terrace 14 on the two steps above this.
A middle terrace 15 and an upper terrace 16 each having a shorter overhang length are provided. Further, the revetment 2 is installed from both ends of the partition wall 12 so as to cover both sides of the space formed between the wall body 11 and the partition wall 12.
Side walls 18, 18 are formed to protrude toward (see FIG. 2). Note that the height of the partition wall 12 is not so high that it does not reach the wall surface of the river 1.

Furthermore, in order to make the fish nest space formed on one side of the partition wall 12 of the fish nest structure 10 a relatively calm area with little influence of waves from ships, etc., the fish nest structures 10 are arranged. It is preferable to arrange a fence 4 having a wave-absorbing structure as shown in FIG. 1 in parallel with the direction.

Such a wave dissipating structure is not limited to the above-mentioned fence structure, but for example, the wave dissipating structure shown in FIGS.
It may have the structure shown in .

What is shown in FIG. 5A is, for example, a plurality of horizontal plates 4b fixed at a predetermined interval above two stakes 4a. The one shown in Figure B has a vertical wave-dissipating plate 4c fixed to a similar pile 4a, and a large number of holes 4d are formed in the vertical wave-dissipating plate 4c.

Between the middle terrace 15 and the upper terrace 16 of this fish nest structure 10, there is an attached algae culture rod 40 which has a liquid-tight structure and is filled with air.
For example, three are provided. In addition, this rod 4
0 is preferably cloudy white rather than transparent.

Furthermore, stones 52 are stacked in the area between the wall 11 and the partition wall 12, and the stone 52 has a cloudy liquid-tight structure and contains phytoplankton containing air. For example, four incubators 60 are provided. Note that an opening 19 is provided in the partition wall 12 for discharging the phytoplankton cultured in the above area to the fish nest space side.

In addition, in order to efficiently cultivate the above-mentioned attached algae and phytoplankton, the ambient temperature should be adjusted to 20°C, for example.
A thermostatic heater (not shown) may be provided to maintain the temperature between .degree. C. and 25.degree.

The fish nest structure 10 as described above is formed with a width w (see FIG. 2) of 1.5 m, for example, and by arranging a large number of such fish nest structures 10,
For example, an artificial reef is formed along the seawall 2 over a length of 250 m.

When arranging such a fish nest structure 10 on a riverbank, as shown in FIG.
4 is preferred.

Next, a system for supplying light to the fish nest structure 10 will be described with reference to FIG. 3 as well.

This light supply system is composed of a light condensing device 31 shown in FIG. 1 and an optical fiber 30.

As shown in FIG. 3, the condensing device 31 has a large number of Fresnel lenses 34 supported by a curved arm 33, and the Fresnel lenses 34 are swingable with respect to the curved arm 33 by a motor (not shown). It is said that In addition, the fulcrum shaft 3 of the curved arm 33
3a is rotatable by a motor (not shown), and as a result, it is possible to direct the Fresnel lens 34 in the direction of sunlight irradiation.

One end of the optical fiber 30 (not shown in FIG. 3) is arranged at the light focusing position of each Fresnel lens 34, so that the light focused by the Fresnel lens 34 is incident thereon. Note that the Fresnel lens 34 has a refractive index that differs depending on the wavelength of sunlight when it passes through the lens. And this optical fiber 3
As shown in FIG. 4, the position on one end of the optical fiber 30 is set at a position where visible light rays are focused, and light of other wavelengths, such as ultraviolet rays and infrared rays, is prevented from entering one end of the optical fiber 30. There is.

As described above, this condensing device 31 has a structure that follows the position of the sun, but its control is performed by calculating the position of the sun based on the year, month, and time indicated by the built-in clock mechanism, and based on this result. fresnel lens 34
so that it moves in the direction of the sun. In addition,
A solar position detection optical sensor 35 is disposed inside the transparent dome 32, and when direct sunlight is coming out, this sensor 35 detects the exact position of the sun and determines the movement position of the Fresnel lens 34. It is now controlled by interrupts.

As shown in FIG. 1, the optical fiber 20 taken out from the light condensing device 31 is extended along the seawall 2 and buried in the fish nest structure 10 by, for example, embedding a sheath tube, and then the upper terrace 16 is buried. It is designed to be inserted into each attached algae culture rod 40 or phytoplankton culture vessel 60 through the rod. In addition, as a structure in which the optical fiber 30 is inserted into each culture rod 40 or culture vessel 60, for example, Japanese Patent Publication No. 61-1728, Utility Model Application No. 59-194706,
The optical radiator disclosed in Japanese Utility Model Application Publication No. 60-130403 can be employed.

Next, the operation of the above artificial reef will be explained.

In general, a requirement for a fish reef is that it must have a living spatial element for fish, that is, a volumetric space for fish to enter, and by creating such a space, an escape effect where fish can escape, It can have a shading effect to avoid seeing through from the outside, and in the case of this embodiment, the fish nest structure 1
The living space for such fish can be guaranteed by the lower terrace 14, middle terrace 15, and upper terrace 16 of 0. Furthermore, by arranging such a structure inside a river, an eddy current is generated, and since fish prefer such an eddy current, it is possible to have a fish-attracting effect.

In addition to the above-mentioned effects, promoting the effect of food for fish is also necessary as a condition for a fish nest, and securing food for fish is especially difficult in highly polluted rivers 1 to satisfy habitat conditions. This has become a major issue.

The biggest advantage of the artificial fish reef of this example is that in addition to ensuring the above-mentioned living space for fish, which is a requirement for a general fish nest, it also provides food for the fish and improves the ecology. The system is at a point where it can be restored.

In order to restore the ecosystem in such contaminated waters, it is necessary to create a food chain.

A food chain is a cycle consisting of producers, consumers, and reducers as shown below.

(Producers) (Primary consumers) Abasics → Photosynthetic plants → Rotifers, Crustaceans → (Secondary consumers) Fish → Organic matter → (Reducers) Bacteria → And, especially important, producers It is the existence of photosynthetic plants that are the Of these, securing light is an absolute requirement in contaminated waters.

Therefore, in this embodiment, sunlight is collected by a light collecting device 31 having a Fresnel lens 34 that follows the position of the sun, and visible light necessary for growing plants is made to enter one end of an optical fiber 30. ing. This optical fiber 30 is connected to each fish nest structure 10.
The light is transmitted to the inside of the attached algae culture rod 40 and the phytoplankton culture vessel 60.

Here, in this embodiment, light is transmitted from the light condensing device 31 to the fish nest structure 10 using a flexible optical fiber 30.
This is achieved by ensuring reliable optical transmission no matter what route is used.
Compared to a method in which a plurality of reflecting mirrors are combined, there is no need to place restrictions on the installation position of the condensing device 31, and maintenance is not required, making it easy to implement.

With the above configuration, by irradiating light into the culture rod 40 and the culture vessel 60, the light diffused by the internal air is transmitted to the culture rod 40 and the culture vessel 6.
From the cloudy white outer surface of 0, relatively peaceful light is emitted. By optimizing this amount of light for photosynthesis of plants, adherent algae grow on the entire outer surface of each rod 40, while the partition wall 1
Incubator 60 placed in a relatively quiet area within 2.
Floating phytoplankton will be cultivated near the outer surface.

In particular, the attached algae culture rod 40 placed in the living space of fish can attract fish by irradiating it with gentle light. By eating these, it becomes possible to gradually grow new attached algae.

These plankton and plants act as producers in the above-mentioned plant chain, so they breed zooplankton, which is the primary consumer, and as a result, secure food for the fish, which are the secondary consumers. be able to. Furthermore, the amount of dissolved oxygen can also be increased as a result of photosynthesis.

In this way, if it becomes possible to maintain a certain feeding effect in the fish nest space and also secure the amount of dissolved oxygen,
Even if carp, crucian carp, etc. are released into a river 1 where water quality is severely polluted, they will be able to live in the fish nest space, and it will be possible to bring fish back to the urban river, thereby restoring the ecosystem. I can do it.
In addition, by ensuring the above-mentioned plant chain,
It can remove pollutants in water bodies and also have a water purification effect.

Although not shown, for example, by stacking stones 52 on the lower terrace 14, middle terrace 15, and upper terrace 16, it is possible to grow plant plants such as moss or algae on the surface of the stones 52. This also makes it possible to enhance the fish-attracting effect.

In addition, as shown in Figure 1, when reeds (reeds) 54 are grown on the upper terrace 16, these plants absorb nitrogen _N2 or phosphorus P, which are pollutant components that are always present in domestic wastewater. This property makes it possible to promote water purification. In other words, it is said that the above plants absorb 1.2 mg of N ₂ and 0.09 mg of P per day on average, and by growing a large number of such plants in a fish nest structure, water purification can be achieved. can be promoted.

In addition, since the above plants grow to a height of about 2 m, they can improve the waterside scenery of River 1, and also ensure the escape effect of small fish by getting between these plants. be able to.

In this way, in this embodiment, even if there is a heavily polluted river, the optical fiber 30 is installed in this water body.
The ecosystem can be restored by irradiating it with light, and the same effect can be achieved even in places where the seawall 2 faces the north and is not exposed to direct light.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. FIG. 6 shows a modification of the fish nest structure 10, and FIG. 6 A shows a partition wall 12 which is a vertical wall surface.
Optical fiber 3 so that light can be irradiated to
0 emission end is arranged. In Figure B, the output end of the optical fiber 30 is arranged so that light can be irradiated onto the lower surface of the upper terrace 16, which is a horizontal wall surface. Both are suitable for increasing the growth of adherent algae that forms on walls.

The one shown in FIG.
In addition to extending the end of the optical fiber 30 to a predetermined depth within the culture vessel 70 and using this end as a light emitting end, the peripheral surface of the fiber 30 is processed so that light can be emitted from various positions in the water depth direction. It is a structure.

In the structure shown in FIG. 1D, the partition wall 12 is also used as a wave-dissipating structure, and basically the arrangement of the fish nest structure shown in FIG. 1 with respect to the waterside is reversed. That is, in the case shown in FIG.
A fish nest structure 10 is constituted by providing a wall body 11 having terraces 14, 15, and 16 formed on the seawall 2 side facing the partition wall 12.

In this way, by arranging the bulkhead 12 farthest from the seawall 2, the seawall of the bulkhead 12 can be easily removed without providing the fence shown in FIG. 1 or the wave-dissipating structure shown in FIGS. 5A and B. Both the cultivation area for attached algae and the living space for fish can be secured as a quiet area.

Furthermore, the present invention is not limited to artificial reefs placed on the banks of urban rivers, but can also be applied to lakes, swamps, bays, etc., or other bodies of water away from the water's edge, especially when placed in places with significant water pollution. However, it is excellent in that it can restore the ecosystem and promote water purification in this area. Furthermore, as for the light guided by the optical fiber 30, one that uses sunlight is superior in that it can utilize natural energy;
It may be a device that uses light from a light source, or a device that uses sunlight or light source light by switching between them.

[Effects of the Invention] As explained above, according to the present invention, in addition to living space elements as essential requirements for fish nests, by adding a configuration for supplying light using optical fibers, it is possible to Even in water areas where light does not reach, photosynthesis can be promoted, and the feeding effect can be enhanced by the reproduction of plants. By creating a chain of plants, various ecosystems can be restored, and water purification can also be promoted.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view showing an example of an artificial fish reef placed on a river bank; Figures 2A, B, and C are a front view, plan view, and cross-sectional view of a fish nest structure;
The figure is a schematic front view showing an example of a condensing device, FIG. 4 is a schematic explanatory diagram for explaining the difference in refractive index according to the wavelength of incident light in a Fresnel lens, and FIGS. 5A and B are , a schematic explanatory diagram for explaining a modified example of the wave-dissipating structure, and FIGS. 6A to 6D are schematic explanatory diagrams for explaining a modified example of the fish nest structure, respectively. 1... River, 2... Bank protection, 10... Fish nest structure, 12... Bulkhead, 14, 16... Terrace, 30
...Optical fiber, 31... Light condensing device, 40,6
0...Incubator.

Claims (1)

[Scope of Claims] 1. A fish nest structure that forms a fish nest space; and an optical fiber that receives natural light or light from a light source from one end and emits the light from the other end supported by the fish nest structure. An artificial fish reef, comprising: an attached algae incubator disposed in the fish nest space of the fish nest structure and into which the other end of the optical fiber is inserted. 2. A partition wall to ensure a quiet area inside, and
A fish nest structure having at least an opening formed in the partition wall that penetrates inside and outside the partition wall, and forming a fish nest space outside the partition wall, and a fish nest structure that allows natural light or light source light to enter from one end. an optical fiber that emits light from the other end supported by the body; and a phytoplankton culture in which the other end of the optical fiber is inserted, and the optical fiber is placed in a quiet region partitioned by the partition wall of the fish nest structure. An artificial fish reef characterized by having a container.