JP2011004768A - Method for creating seaweed bed, and method for proliferating seaweed in sea bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for creating a seaweed bed in which a base itself is hardly washed away by waves, and seaweeds hardly come off from the base even by action of a strong water current such as waves.SOLUTION: This method for creating the seaweed bed includes installing a base for fixing the underground stems or roots of seaweeds by laying a mixture of granulated blast furnace slag and other low-quality components on the sea bottom, and curing and proliferating seaweeds on the base. The granulated blast furnace slag has stability in the sea much greater than the sea sand so as to make outflow by waves extremely less than the sea sand, and has high shear resistance so as to make binding force of seaweeds strong to waves and allow the underground stems or roots of seaweeds to easily twine round. As a result of this, the base itself is hardly washed away by waves, and seaweeds hardly come off from the base even by action of a strong water current such as waves.

Description

  The present invention relates to a method for constructing a seagrass bed by seagrasses such as sea cucumbers (for example, sea bream, core sea bream, giant eel ducks, and Ryukyuus gaum) on a seabed and a method for growing seagrasses on the seafloor.

Plants that grow in seawater are broadly divided into seaweeds that do not have vascular bundles (Hondawala, kombu, etc.) and seaweeds that have vascular bundles (such as sea cucumbers) in the same way as land plants. It grows with roots, and the latter grows by extending the rhizome into sandy or sandy mud.
The place where seaweeds are clustered is called the seagrass bed (commonly known as Amamo Field). Such a seagrass bed is a production area for marine flora and fauna in coastal waters, and can be said to be an indispensable place as a habitat for useful seafood, a spawning ground for seafood, a habitat for juvenile fish, and a feeding ground.

However, in recent years, seagrass beds in coastal waters have been rapidly disappearing and declining due to the effects of sea sand loss and coastal landfills. It is demanded.
As a method for recovering and creating a seagrass bed that has declined or disappeared, a method of transferring sand collected at another place and transplanting or sowing seagrass there can be considered.

However, a large amount of high-quality sand (sea sand, river sand, mountain sand, etc.) is required to create such a seagrass bed, and such a large amount of natural materials must be collected (mined) elsewhere. Will cause new environmental destruction, which is undesirable.
On the other hand, as a material for creating a seagrass bed, it is possible to use dredged soil that is generated in large quantities during marine civil engineering work such as harbor construction and channel excavation (dredge), but this kind of dredged soil is not of constant quality. May contain large amounts of sludge such as organic mud. Such dredged soil containing a large amount of sludge is not only suitable as a material for creating seagrass beds, but also when laying on the seabed or after laying, fine particles may flow into the seawater, making the seawater cloudy, It may cause pollution of the sea area by elution of nutrient salts and hydrogen sulfide.

In addition, the seaweed breeding form in the seagrass bed is based on seaweeds that grow and breed with a basement stem (sandy mud in the case of natural seaweed seaweed beds) around the basement stem. It is required that the base itself is not easily washed away by waves or the like, and that seagrasses are not easily removed from the base even when strong water currents are applied.
However, seagrass beds based on natural sand (sea sand, river sand, mountain sand, etc.) are prone to runoff by waves, etc., and even if seaweeds once settled, strong water flows due to waves etc. If it acts, the whole rhizome will come off and there is a problem that seaweeds are difficult to grow.

Conventionally, as a technique for securing a stable base and fixing seaweeds against such problems, a method of creating a seagrass bed by laying mats such as biodegradable resin on the seabed (for example, patents) Document 1 etc.), a method of installing a structure composed of a steel net or the like (for example, Patent Document 2 etc.) has been proposed.
However, in these conventional methods, it takes a lot of time and labor to create a seagrass bed with a large area, and the creation cost is also great. In addition, seaweeds (such as those that form reef-like seaweeds such as Honda Walla) naturally grow on structural members installed on the seabed (for example, the frame part or net part in Patent Document 2). Breeding may cause a shortage of the amount of light hitting seaweeds and inhibit growth.

Japanese Patent Laid-Open No. 10-181976 JP 2002-171852 A

  Accordingly, an object of the present invention is to provide a seagrass bed where the base itself is less likely to be washed away by waves, etc., and seagrass beds can be created at low cost from which seagrasses are unlikely to escape from the bases even when strong water flows due to waves. It is to provide a creation method. Another object of the present invention is to provide a method for forming a base on which seagrasses can stably grow and propagate on the seabed, and for propagating seaweeds on the base.

  In order to solve the above-mentioned problems, the present inventors have examined a base material suitable for seagrass bed construction or seagrass breeding, and as a result, blast furnace granulated slag generated in the steel manufacturing process is used as the base material. It has been found that it has optimal physical properties and can form a seagrass colonization base that is far superior to other sediment components such as natural sand. Since this granulated blast furnace slag is produced in large quantities in the steel manufacturing process, it can be obtained at a low cost and in large quantities. Can be formed.

The present invention has been made based on such findings, and the features thereof are as follows.
[1] A blast furnace granulated slag is laid on the seabed to provide a base for anchoring the roots or roots of seaweeds, and seagrass beds are formed by growing and growing seagrasses on the base. How to create a seagrass bed.
[2] A base for laying a mixture of ground granulated blast furnace slag and other bottom sediments on the sea floor to fix the roots or roots of seaweeds is established, and seagrasses are grown and grown on the base. A method for constructing a seaweed seaweed bed, characterized by forming a seaweed bed.

[3] In the creation method of [2] above, the other bottom constituent material is at least one selected from natural sand, dredged soil, bottom soil of the laying place, and slag other than blast furnace granulated slag. A method for constructing a seagrass bed, characterized by being.
[4] A method for creating a seagrass bed, wherein the ratio of granulated blast furnace slag in the mixture is 20% by volume or more in the method of [2] or [3].
[5] In the construction method according to any one of [1] to [4] above, a seaweed algae farm characterized in that seaweeds are allowed to grow and propagate by transplanting seaweeds on a base or seeding seaweed seeds. Creation method.

[6] Seagrass beds where seagrass colonies grow and grow on a base constructed with ground granulated blast furnace slag.
[7] A seagrass bed where seagrass colonies grow and grow on a base constructed by laying a mixture of granulated blast furnace slag and other sediment components on the seabed.
[8] A method for growing seagrass on the seabed, comprising laying blast furnace granulated slag on the seabed to provide a base for fixing the rhizomes or roots of seagrasses, and allowing the seagrass to grow and grow on the base.

[9] A base for laying a mixture of ground granulated blast furnace slag and other bottom sediments on the seabed to fix the roots or roots of seaweeds, and the seagrass is grown and propagated on the base The seaweed breeding method on the sea floor.
[10] In the breeding method according to [9], the other sediment constituent material is at least one selected from natural sand, dredged soil, bottom soil of the laying place, and slag other than blast furnace granulated slag. A method for propagating seaweeds on the sea floor, characterized in that it exists.
[11] The method for propagating seagrasses on the seabed according to [9] or [10] above, wherein the proportion of granulated blast furnace slag in the mixture is 20% by volume or more.

[12] The method for propagating seaweeds according to any one of [8] to [11] above, wherein the seaweeds are allowed to grow and propagate by transplanting seaweeds on a base or seeding seaweed seeds. .
[13] A base material for seagrass bed formation or seaweed breeding characterized by comprising granulated blast furnace slag.
[14] Ground for cultivating seagrass beds or breeding seaweed, characterized by comprising blast furnace granulated slag and one or more mixtures selected from natural sand, dredged soil, and slag other than blast furnace granulated slag Wood.

  Since granulated blast furnace slag is much more stable in the sea than sea sand, the outflow due to waves is much less than sea sand, and because of its high shear resistance, seaweeds have a binding force against waves. It has a characteristic that it is strong, and the rhizomes and roots of seaweeds are easily entangled. Moreover, since granulated blast furnace slag is generated in large quantities in the steel production process, it can be obtained in a large amount at a low cost. For this reason, according to the method for creating a seagrass bed of the present invention, it is possible to reduce the cost of the seagrass bed, where the base itself is less likely to be washed away by waves, etc. Can be created. Further, according to the method for propagating seaweeds of the present invention, a base on which seagrass can stably grow and propagate can be formed on the seabed, and seaweeds can be effectively propagated on the base.

First, the construction method of the seaweed seaweed bed of the present invention will be described. The seagrass beds that are the subject of the present invention are seaweeds such as eelgrass (for example, eelgrass, eelgrass, giant eelgrass, ryucus gaum) that grow and propagate by extending the rhizomes in sandy or sandy soil This is the seabed that is generally called an ammo field.
In order to create such a seaweed algae field, in the seagrass algae field construction method of the present invention, a blast furnace granulated slag or a mixture of blast furnace granulated slag and other sediment constituents is laid on the sea floor, A base for establishing the rhizomes or roots is provided, and seagrass beds are formed by growing and propagating seaweeds on this base.

Granulated blast furnace slag is one in blast furnace slag of steelmaking slag system a slag solidified by water砕化treatment, the particle size is greater than the sea sand (typically, 1.0 to the D ₅₀ The particle size is about 2.0 mm), and the specific gravity is slightly larger than sea sand. Furthermore, a major feature of the blast furnace granulated slag is that the slag particles have an angular shape, and because of this shape, the physical characteristics of a large internal friction angle and high shear resistance. have.
Since granulated blast furnace slag is generated in large quantities in the steel manufacturing process, it can be said that it is a base material that can be obtained in large quantities at low cost.

When constructing a seagrass bed in the method of the present invention, it is possible to lay only blast furnace granulated slag as a base material, but a part of the base material is another bottom material component, and blast furnace granulated slag and other A mixture with a bottom constituent material may be used as a base material. As this other sediment constituent material, one or more selected from natural sand, dredged soil, bottom soil of the laying place, and slag other than blast furnace granulated slag can be used. As the above natural sand, sea sand, river sand, mountain sand, etc., as dredged materials, such as those generated by marine civil engineering work (dredge) such as port construction and channel excavation, as slag other than blast furnace granulated slag, Various slags such as steelmaking slag, municipal waste melting slag, and municipal waste incineration ash melting slag can be used.
In addition, although it is most preferable to use the blast furnace granulated slag as it is, it may be lightly crushed.

  However, from the viewpoint of obtaining the operational effect by using blast furnace granulated slag as a base material as described later, it is preferable to use blast furnace granulated slag alone, even when mixed with other bottom sediment constituent materials, The proportion of granulated blast furnace slag in the mixture is 20% by volume or more, preferably 40% by volume or more, more preferably 60% by volume or more, and particularly preferably 80% by volume or more. In addition, volume% here shall mean the volume ratio of the simple material before mixing (Claims 3 and 6 are also the same).

On the other hand, seaweeds such as sea cucumber absorb nutrients such as nitrogen and phosphorus from the roots of the rhizomes. From the standpoint of the growth of seaweeds, the base on which they grow should contain a certain amount of organic matter. In this regard, blast furnace granulated slag is substantially disadvantageous in terms of nutrient absorption by seaweeds because it contains substantially no organic matter, but even if blast furnace granulated slag is used alone as a base material, suspended matter in seawater There is no big problem because organic matter is supplied to the substrate by sedimentation of the substrate.
However, from the viewpoint of preliminarily containing organic matter in the base and promoting the growth of seaweeds, the bottom constituent material containing blast furnace granulated slag and organic matter, preferably the loss on ignition is about 5 to 30 mass%, preferably 10 It is a mixture with a sediment constituent material (for example, sea sand, dredged soil, etc.) of about ~ 20 mass%, and the ratio of the sediment constituent material is 1 to 40% by volume, preferably about 10 to 30% by volume. It is desirable to use

The seabed on which the base material is laid is preferably a place suitable for the growth of seaweeds such as sea cucumbers. In particular, the seabed with a relatively shallow depth that allows light to reach the seabed. It is preferably about 10 m to 10 m, preferably a sea bed with an average light intensity of 3.0 E / m ² / day or more. Other preferable conditions include that the tide is gentle, that there are few waves, that the water temperature is about 10 to 25 ° C., and that the bottom of the seabed is small.

The laying thickness of the blast furnace granulated slag or a mixture of blast furnace granulated slag and other sediment components at the seabed (the thickness of the base formed) may be appropriately determined according to the depth of the underwater stem of the seaweed, In general, the thickness is preferably 20 cm or more.
In order to create and breed seagrass on the installed base to form a seagrass bed, you can wait for the seagrass to naturally grow without doing anything special, but form a seagrass bed early. For this, it is preferable to transplant seaweeds on the base or sow seeds of seaweeds.

  The seagrass bed formed by the method of the present invention described above is (a) a seagrass bed where seagrass groups have grown and grown on a base provided with blast furnace granulated slag laid on the seabed, or (b ) Seagrass algae where seagrass groups grew and propagated on a base constructed by laying a mixture of blast furnace granulated slag and other sediment components on the seabed. The field functions effectively as a production area for marine flora and fauna in coastal waters (useful seafood habitat, seafood spawning ground, juvenile fish breeding ground, feeding ground, etc.).

  Next, the method for breeding seaweeds according to the present invention provides a base for fixing the ground stems or roots of seaweeds by laying blast furnace granulated slag or a mixture of blast furnace granulated slag and other sediment components on the seabed. The seaweeds grow and grow on this base. This method of the present invention is not limited to the creation of a seagrass bed, but preferred conditions for a mixture of blast furnace granulated slag and other sediment components, blast furnace granulated slag or blast furnace granulated slag and other bottom The laying conditions of the mixture with the quality constituent material are the same as the method for constructing the seaweed algae described above.

When the blast furnace granulated slag is used as a base for growing and propagating seaweeds in the seagrass bed construction method and seaweed breeding method of the present invention, the following specific effects are obtained.
(1) Wave resistance stability In order to form seagrass beds on the seabed or to relocate seagrass, if sand collected at another location is transferred, the sand will flow out from the sea, and the foundation for growing seagrass There is a fundamental problem that cannot be maintained. On the other hand, granulated blast furnace slag has an angular shape, so the internal friction angle is large, and since the particle size is larger and the specific gravity is slightly larger than sea sand, the stability in water is better than that of sea sand. Remarkably large, and the outflow caused by waves is much less than sea sand. For this reason, the base for growing seaweeds can be stably maintained.

(2) Seagrass colonization Seagrass and other seagrasses grow and proliferate by extending the rhizomes and roots to the bottom sediment and entwining them in the bottom sediment constituent material so that they do not easily escape from the bottom sediment due to waves and the like. . However, when the bottom sediment is sand, there is a problem that the rhizome is easily removed from the bottom sediment due to waves and the like, and seaweeds are difficult to grow. On the other hand, blast furnace granulated slag has higher shear resistance than sea sand due to the above-mentioned particle shape, so seagrass has a strong binding force against waves, etc. Hard to be pulled out. In addition, due to its unique particle shape and moderate roughness, the rhizomes and roots of seaweeds are more likely to be entangled than sea sand, and by serving as their anchors, it is difficult to escape seagrasses. In particular, the latter greatly contributes to the establishment of seaweeds immediately after germination.

  A plurality of 2 m × 2 m sections were provided on the flat seabed, and different amamo field base materials (sediment) were laid in a thickness of 50 cm in each section, and 30 strains of each of the sea eels were transplanted there. The interval between the sections was 2 m. Table 1 shows the results of examining the number of Amamo strains after one year.

  A plurality of 2 m × 2 m sections were provided on a flat seabed, and different sections of the eelgrass ground base material (bottom sediment) were laid in a thickness of 50 cm in each section. 100 seeds were divided into about 5 equal parts and sown in 5 sections in 1 section. The interval between the sections was 2 m. The number of strains germinated and grown after 3 months was investigated. The results are shown in Table 2.

  INDUSTRIAL APPLICABILITY The present invention can be used to recover and create a seaweed algae field in a sea area where the seaweed algae field has faded or disappeared.

Claims (6)

  By laying a mixture of ground granulated blast furnace slag and other sediment components on the seabed to establish a basement for roots or roots of seaweeds, transplanting seaweeds on the basement or sowing seeds of seaweeds A method for constructing a seagrass bed, characterized in that seaweeds are grown and grown to form a seagrass bed.   The other sediment constituent material is at least one selected from natural sand, dredged soil, bottom soil of the laying place, and slag other than blast furnace granulated slag. How to create a seagrass bed.   The method for constructing a seagrass bed according to claim 1 or 2, wherein the ratio of granulated blast furnace slag in the mixture is 20% by volume or more.   By laying a mixture of ground granulated blast furnace slag and other sediment components on the seabed to establish a basement for roots or roots of seaweeds, transplanting seaweeds on the basement or sowing seeds of seaweeds A method for propagating seaweeds on the seabed, characterized in that seagrasses are allowed to grow and grow.   The other sediment constituent material is at least one selected from natural sand, dredged soil, bottom soil of the laying place, and slag other than granulated blast furnace slag. How to grow seagrasses on the sea floor.   The method for breeding seaweeds on the seabed according to claim 4 or 5, wherein the proportion of granulated blast furnace slag in the mixture is 20% by volume or more.