Method for cultivating seaweeds such as konbu and wakame using nursery rope

Abstract

To provide a method for cultivating seaweeds such as konbu and wakame using a nursery rope.SOLUTION: Provided is a method for cultivating seaweeds such as konbu and wakame using a nursery rope, the method including: placing a nursery rope 10 having seaweed seeds or seedlings attached thereto on a sandy region of the seabed; and allowing the thalli of the seaweeds to lie flat and grow on the nursery rope as a base.SELECTED DRAWING: Figure 2a

Description

Technical Field

[0001] The present invention relates to a method for cultivating seaweeds such as kelp and wakame using a cultivation rope.

Background Art

[0002] The cultivation of seaweeds such as kelp and wakame is very important from the viewpoints of the health and sustainability of the earth and the food security of humanity. In recent years, seaweeds such as kelp and wakame have attracted great attention as blue carbon carriers. Blue carbon refers to carbon dioxide (CO2) absorbed and stored by marine ecosystems. Seaweeds absorb a large amount of carbon dioxide through photosynthesis and release oxygen. That is, seaweeds become important carriers of blue carbon and contribute to mitigating climate change. Although it is difficult to expand green areas on land, there are vast unused sea areas in the ocean. In addition, seaweeds such as kelp and wakame are important food sources in many regions, especially in Asian countries. They contain rich nutrients and are used in various dishes. Therefore, the cultivation of seaweeds such as kelp and wakame is important for food security.

[0003] In recent years, the production of seaweeds such as kelp and wakame has been decreasing in many regions. Due to changes in the marine environment, harsh climate conditions, and damage by pests, it has become difficult for natural kelp and wakame to grow, resulting in a decline in production. This not only affects food supply but also means a decrease in the role of blue carbon played by kelp and wakame. The cultivation of seaweeds such as kelp and wakame can be a sustainable means of food production if properly managed. It does not require chemical fertilizers or pesticides and also contributes to maintaining natural resources. For the above reasons, the cultivation of seaweeds such as kelp and wakame plays an important role in maintaining the health of the earth, ensuring food supply, and promoting a sustainable society.

[0004] There are various methods for the conventional marine cultivation of seaweeds such as kelp and wakame. For example, floating cultivation is a cultivation method in which a cultivation rope (rope) is suspended from a floating body (float) and placed near the sea surface to grow kelp and wakame. For example, the procedure is as follows. (Installation) First, floating bodies such as plastic and styrofoam are placed on the sea surface. Cultivation ropes are attached to these floating bodies, and seedlings of kombu and wakame are suspended from the ropes. (Growth) Kombu and wakame grow along the cultivation ropes suspended from the floating bodies. Since cultivation is carried out near the sea surface, they can receive a large amount of sunlight necessary for photosynthesis. (Harvest) When kombu and wakame grow to a certain size, they are harvested. Since floating body cultivation is carried out near the sea surface, the harvesting work is relatively easy. For example, Patent Documents 1 to 3 are an example of floating body cultivation (sea surface cultivation) of kombu.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] When cultivating seaweeds such as kombu (kelp) and wakame on the sea surface, there are many problems, such as fluctuations in environmental conditions, the risk of fouling organisms and predation, the problem of nutrient supply, artificial pollution, and physical damage. Since these seaweeds are highly dependent on natural environmental conditions, especially water temperature, salinity concentration, etc., fluctuations in seawater temperature and abnormal weather due to climate change have a great impact on cultivation. The supply of nutrients is particularly important in sea surface cultivation. However, in the sea, it is difficult to achieve a uniform distribution of nutrients seasonally and spatially, so growth retardation and quality degradation due to nutrient deficiency are likely to occur. In addition, pollution and turbidity caused by the inflow of chemical substances from terrestrial waters such as river water and red soil are also major problems. Light terrestrial water diffuses along the sea surface, which has an adverse effect on the growth of seaweeds cultivated on the sea surface and natural seaweeds, and may also affect the health of consumers. In addition, natural disasters such as strong winds and high waves can cause damage to cultivation facilities, damage to the seaweeds themselves, a decrease in the harvest, and an extension of the time to harvest. In recent years, the harvest of high-grade natural kelp soup stock such as Macrocystis pyrifera has decreased significantly (Non-Patent Document 1). While kelp can grow under lower light levels than highly competitive Sargassum species, it is said to have a high nutrient requirement. Especially in the southern and eastern parts of Hokkaido, Japan, a nutrient-rich cold current (Oyashio) flows southward from winter to spring with low water temperature, but from early summer to autumn, as the seawater temperature rises, the influence of the nutrient-poor warm current (Tsushima Warm Current) increases, and the sea area becomes nutrient-poor and unsuitable for the growth of kelp. Furthermore, when the seawater temperature rises due to global warming, etc., kelp that is vulnerable to high water temperature may cause withering and shedding or become difficult to survive the summer. Therefore, it is important to grow kelp at the bottom of the sea where the water temperature is low and the nutrients are rich. Natural kelp that actually grows at the bottom of the sea becomes withered and smaller during the summer, but after overcoming the summer, it grows into a kelp that is clearly thicker, wider, and longer compared to the first year. This is used as high-grade kelp soup stock.

Means for Solving the Problems

[0008] The method for cultivating seaweeds such as kombu and wakame using the cultivation rope of the present invention is characterized in that a cultivation rope with seaweed seeds or seedlings attached is placed in a sandy area on the seabed, and thalli of seaweeds such as kombu and wakame are laid down and grown with the cultivation rope as a base.

Effects of the Invention

[0009] It is possible to efficiently cultivate seaweeds such as kombu and wakame while efficiently taking in seawater rich in nutrients existing near the sandy area on the seabed.

Brief Description of the Drawings

[0010]

Fig. 1a

Fig. 1b

Fig. 1c

Fig. 2a

Fig. 2b

Fig. 2c

Fig. 3

Fig. 4a

Fig. 4b

Fig. 4c

Fig. 5

Fig. 6

Fig. 7a

Fig. 7b

Fig. 8a

Fig. 8b

Fig. 8c

Embodiments for Carrying out the Invention

[0011] Hereinafter, embodiments of a method for cultivating seaweeds such as kelp and wakame according to the present invention will be described with reference to the drawings. The kelp of the present invention may be of any kind, but in particular, the following kelp can be preferably applied. For example, Saccharina japonica, Undaria pinnatifida, Laminaria ochotensis, Eisenia bicyclis, Undaria peterseniana, Undaria pinnatifida var. religiosa, Saccharina longissima, Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, Undaria undarioides, Undaria pinnatifida var. hakodatensis, Undaria pinnatifida var. yendoi, Undaria pinnatifida var. crassifolia, etc. In addition, the cultivation method of the present invention can also be applied to wakame. It is particularly suitable for green wakame and Undaria pinnatifida that grow prostrate even naturally.

[0012] The method for cultivating seaweeds such as kelp and wakame using the cultivation rope of the present invention is characterized in that a cultivation rope with seaweed seeds or seedlings such as kelp and wakame is installed in a sandy area on the seabed, and the thallus of the seaweed is grown by lying prostrate with the cultivation rope as a base. Here, growing the thallus of the seaweed by lying prostrate means that the cultivation rope for cultivation is installed in a sandy area on the seabed, a part of the thallus of the seaweed is in contact with the sandy area, and the thallus is grown so as to extend horizontally along the seabed. By growing while lying the thallus in the same way as naturally growing kelp, it is possible to efficiently absorb nutrients that are abundant near the sandy area on the seabed. In addition, by installing the cultivation rope in the sandy area on the seabed, the damage caused by sea urchins can also be suppressed. Sea urchins cannot move on the sand surface except when there is no influence of waves. It is possible to effectively utilize sea areas where the sea surface cannot be used due to waves or the like. Here, the seabed sandy area means a specific group of points within a range of 1 meter in radius in plan view, where at least 70% or more is composed of sandy ground. More preferably, the proportion of this sandy ground is 80% or more, and even more preferably 90% or more.

[0013] The cultivation rope used in the invention is slender and has a long straight part, and does not include a net-like structure. It is desirable that the length of this cultivation rope is at least 5 m or more. Considering the arrangement in the sandy area, the working efficiency is greatly improved by using this cultivation rope. Seaweed cultivation such as kombu is carried out on the seabed using one or two or more such cultivation ropes. By using a cultivation rope with a slender and long straight part, it is also possible to efficiently proceed with the harvesting work. Fig. 1a is a plan view illustration when the cultivation rope 10 is arranged in the seabed sandy area 50. The length of the cultivation rope of the present invention is defined as the length of the part arranged in the sandy area in plan view. Fig. 1b is an illustration of the cultivation rope 10 arranged in the rocky area and the sandy area 50 sandwiched between the rocky areas. The size of the cultivation rope, the size of the rocky area, the size of the sandy area, etc. in the illustration do not necessarily reflect the actual size. Fig. 1c is an illustration of the cultivation rope 10 arranged in two sandy areas divided by rocky areas. When the cultivation rope is arranged across a plurality of sandy areas like this, the length of the cultivation rope is the sum of the lengths of the cultivation ropes in each sandy area. For example, in Fig. 1c, the sum of "cultivation rope length (1) and cultivation rope length (2)" is taken as the length of the cultivation rope. In addition, in Fig. 1a, Fig. 1b, and Fig. 1c, the cultivation rope is arranged linearly, but actually it does not have to be linear. Even if it is actually arranged linearly, it is assumed that the rope will bend due to the influence of ocean currents, etc. The length of the cultivation rope is the length measured along the rope. That is, the length of the cultivation rope arranged in a bent shape is considered to be the same as the length when it is stretched straight. Also, in Fig. 1a, Fig. 1b, and Fig. 1c, the illustrations of seaweeds such as kombu and wakame are omitted.

[0014] The material of the cultivation rope for aquaculture can be any material as long as the holdfasts of kelp and wakame can easily take root. For example, synthetic fibers such as nylon, polypropylene, and polyester. Natural materials such as bamboo and hemp may also be used. The cultivation rope preferably has a circular cross-section. A circular cross-section is a shape with the minimum resistance to water flow. This makes it less susceptible to the influence of ocean currents, and the cultivation rope itself can be more stable in position and less likely to move. The friction and impact when the cultivation rope moves due to the influence of ocean currents can also be minimized. Since the roots of kelp and wakame tend to grow by wrapping around so as not to flow out, in the case of a circular cultivation rope, the roots of kelp can wrap around the cultivation rope and grow, thus preventing the algal thalli from flowing out. By using the cultivation rope as a substrate for seaweed attachment, the adhesion to the substrate for seaweed attachment can be enhanced compared to kelp and wakame growing naturally.

[0015] Figure 2a is an illustration when the cultivation rope 10 of the present invention is arranged in the sandy area 50 on the seabed. The top of the figure is the sea surface and the bottom of the figure is the seabed (※Note that the size of the cultivation rope in the illustration, the distance between the seabed and the sea surface, the distance between the sandy area and the cultivation rope, etc. are described with emphasis on clarity and do not necessarily accurately reflect the actual dimensions). It is desirable to place the cultivation rope in the sandy area on the seabed where submarine spring seawater gushes out, and cultivate seaweeds such as kelp and wakame. Submarine spring seawater means water containing salt that gushes out from the seabed at a shallow depth. Submarine spring seawater may mainly gush out from the seabed in the range from the shore breakwater to a depth of about 10 m. This submarine spring seawater contains a large amount of nutrients such as amino acids, and it is considered that these substances are transferred from underground fresh water to underground seawater at the interface between underground fresh water and underground seawater along the coast (for details, see Patent Document 4, Patent Document 5, Non-Patent Document 2, etc.). Placing the cultivation rope in the sandy area where submarine spring seawater gushes out and seaweeds such as kelp and wakame By cultivating them, aquaculture can be carried out while efficiently taking in seawater containing more nutrients. Note that just because it is generally a sandy area does not necessarily mean that submarine spring water is gushing out. It is desirable to select a sandy area on the seabed where a certain amount of submarine spring water is gushing out. For example, it is desirable to select a sandy area where the submarine spring water gushes out at 5 liters / m 2 / hour or more. More preferably, it is 10 liters / m 2 / hour or more, 20 liters / m 2 / hour or more, 40 liters / m 2 / hour or more, and more preferably 60 liters / m 2 / hour or more, and even more preferably 100 liters / m 2 / hour or more.

[0016] Since seawater containing nutrients derived from submarine spring water exists in greater amounts near the sandy area on the seabed where it gushes out, it is desirable to place the cultivation rope near the sandy area on the seabed and cultivate seaweeds such as kombu and wakame. Specifically, it is desirable that the cultivation rope of the present invention is installed within 1 m in the vertical direction from the sandy area on the seabed. More preferably, it is within 90 cm, more preferably within 80 cm, more preferably within 70 cm, more preferably within 60 cm, more preferably within 50 cm, more preferably within 40 cm, more preferably within 30 cm, more preferably within 20 cm, more preferably within 10 cm, more preferably within 5 cm. Even more preferably, it is desirable that the cultivation rope is in contact with the sandy area on the seabed. Here, the nutrients derived from submarine spring water are, for example, amino acids, nutrient salts (salts such as phosphates, nitrates, nitrites, ammonium salts, silicates, etc.), vitamins, trace elements (iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), etc.), inorganic elements (calcium (Ca), magnesium (Mg), sulfur (S), etc.).

[0017] Figure 2b is an illustration of the case where the cultivation rope is arranged to contact the sandy area on the seabed. By installing the cultivation rope so that it contacts the sandy area, the polishing effect between the cultivation rope and the sand is achieved. Due to the polishing effect of the sand, it becomes difficult for the competitors of the gametophytes, germlings, and larvae of kelp, such as Hormosira banksii, red algae, and diatoms, to grow on the cultivation rope. It is desirable that 50% or more of the total length of the cultivation rope arranged in the sandy area is in contact with the sandy area. More desirably, it is 60% or more, and even more desirably, it is 70% or more.

[0018] Figure 2c is an illustration of the example shown in Figure 2a as viewed from the cross-sectional direction of the cultivation rope. As described above, it is desirable that the cross-section of the cultivation rope is substantially circular. Note that in Figures 2a, 2b, and 2c, the illustrations of seaweeds such as kelp and wakame are omitted.

[0019] Figure 3 is an aerial photograph of an example of a sea area suitable for implementing the aquaculture method of the present invention. The area surrounded by the square in the figure is an example of the sea area where the cultivation rope is arranged. The cultivation rope is installed in the sandy area on the seabed of this sea area, and aquaculture of seaweeds such as kelp and wakame is carried out. As the cultivation rope installed on the seabed, those with pre-seedling may be used. Also, natural seeding at the location where the cultivation rope is installed or at other locations is acceptable. The sea area surrounded by the square in Figure 3 is about 50 m to 180 m from the shore wall and the water depth is about 3 to 7 m.

[0020] Furthermore, it is desirable that the sandy area around the cultivation rope arranged on the seabed is covered with the thalli of seaweeds such as kelp and wakame. The submarine spring seawater containing nutrients is surrounded by the sandy area and the thalli, and the thalli of seaweeds such as kelp and wakame can effectively take in nutrients. That is, it is desirable that the sandy area surrounded by the cultivation rope and a point at a predetermined range away from the cultivation rope in plan view is covered with the thalli of seaweeds.

[0021] Specific conditions will be described with reference to Figures 4a and 4b. Figure 4a is a plan view illustration of the cultivation rope 10 disposed in the sandy area 50, showing a thallus cultivation area 60 surrounded by a point (dotted line part) at a predetermined distance from the cultivation rope 10 and the cultivation rope 10. The thallus cultivation area 60 is defined as an area surrounded by a point at a predetermined distance in one of the vertical directions in plan view from the cultivation rope and the cultivation rope 10. This thallus cultivation area can be set widely by lodging and growing thalli of seaweeds such as kombu and wakame on the cultivation rope as a base. In the present invention, it is desirable that at least 50% or more of the sandy area (thallus cultivation area 60) between the cultivation rope 10 and a distance of 50 cm from the cultivation rope 10 is covered with thalli in plan view. More preferably, it is 60% or more, still more preferably 70% or more, and even more desirably 80% or more. By the thalli covering the sandy area more densely, nutrients derived from submarine upwelling sea water can be effectively taken in. Also, the larger the thallus cultivation area 60 is, the more efficiently seaweeds such as kombu and wakame can be cultivated. The thallus cultivation area 60 is not limited to the area of 50 cm from the cultivation rope, and can be 50 cm or more, specifically 60 cm or more, 70 cm or more, 80 cm or more, 90 cm or more, 100 cm or more, etc.

[0022] Figure 4b is an illustration of an example in the case where kombu is also cultivated on the other side of the cultivation rope in Figure 4a. A thallus cultivation area 61 is set separately from the thallus cultivation area 60 in Figure 4a. Thus, the thallus cultivation area can be set on one or both sides of the cultivation rope 10 in plan view. Also in that case, it is desirable that at least 50% or more of the thallus cultivation areas 60, 61 is covered with thalli. More preferably, it is 60% or more, still more preferably 70% or more, and even more desirably 80% or more. The length of the thallus cultivation areas 60, 61 in the direction of the cultivation rope is at least 5 m or more. Since the thallus cultivation area is defined along the extending direction of the cultivation rope, the shape of the thallus cultivation area in plan view is rectangular when the cultivation rope is straight, but becomes a corresponding shape when the cultivation rope is curved. This example is particularly effective when growing the thalli of kelp or wakame to a certain size. For example, it is desirable that the length of the thallus be 50 cm or more. As the thallus grows longer, it tends to grow more prostrate, so that the submarine spring seawater containing nutrients is further surrounded by the sandy area and the thallus, enabling kelp or wakame to take in nutrients more effectively. The length of the thallus may be 60 cm or more, 70 cm or more, 80 cm or more, 90 cm or more, or 100 cm or more.

[0023] It is also desirable to arrange a plurality of cultivation ropes in proximity and grow them so that the sandy area between the cultivation ropes is covered by the thalli of seaweeds such as kelp or wakame. Figure 4c is an illustration showing two cultivation ropes arranged in proximity. The length between the cultivation ropes can be appropriately selected according to the seaweed to be cultivated, but it is particularly desirable that it be 2 m or more and 5 m or less. More preferably, it is 2 m or more and 4 m or less, and even more preferably, it is 2 m or more and 3 m or less. This enables more efficient utilization of the seawater containing nutrients on the seabed.

[0024] It is desirable that a part of the thalli of kelp or wakame cultivated on the cultivation ropes be in contact with the sandy seabed. It is desirable that 20% or more of the thalli of kelp or wakame cultivated on the cultivation ropes be in contact with the sandy seabed. For example, if there are 1000 thalli of kelp or wakame cultivated on the cultivation ropes, it is desirable that a part of 200 or more thalli corresponding to 20% thereof be in contact with the sandy seabed. More preferably, it is 30% or more. Figure 5a is an illustration showing that the thalli of kelp or wakame are in contact with the sandy area on the seabed. The distance between the sandy area on the seabed and the cultivation rope can be set within the range described above.

[0025] It is also desirable that the temporary roots of kelp or wakame be adsorbed on the lower surface side (seabed side) of the cultivation rope. Here, the lower surface side is the side that cannot be seen from above in plan view. When the temporary roots of kelp or wakame are adsorbed on the upper surface side (sea surface side) of the cultivation rope, the thalli of kelp or wakame will grow upward, and the efficiency of growing so that the thalli extend horizontally along the seabed will deteriorate.

[0026] The cultivation method of kombu and wakame using the present invention will be described. <Preparation of seedlings> The seedlings are either naturally collected or artificially propagated. The cultivation rope in Fig. 6 has the seed yarn containing the artificially propagated seedlings sandwiched therein. <Installation of cultivation rope> The cultivation rope is installed in the sandy area on the seabed. This cultivation rope may be directly placed on the sand, or the cultivation rope can be installed at a height within 1 m from the sandy area on the seabed using a member for hanging the cultivation rope. Figs. 7a and 7b are examples of the cultivation method of the present invention. In both cases, the cultivation rope is installed on the sandy seabed using the structures arranged under the surface (seabed) of the sandy area. In Fig. 7a, since the sand layer is relatively shallow, the surface of the structure is also located above the sandy surface. By arranging several structures on the seabed and tying the cultivation rope to the structures, the cultivation rope can be fixed to the sandy seabed. In the case of natural seeding, seeding is carried out after the installation of the cultivation rope. In Fig. 7b, since the sand layer is relatively thick, the surface of the structure is located below the sandy surface. Therefore, a chain provided with a buoy (float) at the tip is connected to the structure and the chain is arranged on the seabed. By connecting the cultivation rope to this chain, the cultivation rope can be installed in the sandy area on the seabed. Also, the distance between the cultivation rope and the sandy surface can be adjusted. Instead of the chain, other arbitrary means such as a support column and a cultivation rope that can adjust the distance may be used. Iron structures having a specific gravity higher than that of the sand containing seawater are installed at both ends of the cultivation rope and can be deliberately buried in the sand. This can enhance the stability of the structure and minimize the influence of typhoons, tsunamis, and rough seas. Also, when installing the cultivation rope near the sandy seabed, the control of the position of the cultivation rope becomes easier.

[0027] <Management> During the growth process of kombu (or wakame), the situation in the sea and the growth state of kombu (or wakame) are regularly observed. Ensure healthy growth so that kombu (or wakame) does not get sick or eaten by other organisms. <Harvest> Harvesting is carried out at the stage when the kombu (or wakame) has grown sufficiently. This is generally done manually or using dedicated machinery.

[0028] Figures 8a, 8b, and 8c are actual photos of cultivating kombu (or wakame) on the cultivation ropes of the embodiments of the present invention.

[0029] The present invention is a method for cultivating kombu and wakame, which is different from a method for growing kombu and wakame aimed at increasing the number of individuals of kombu and wakame. The present invention aims to efficiently grow kombu and wakame according to the invention described in the claims. The illustrations in the figures shown so far are only schematically illustrated, and the scale of the actual structure dimensions does not necessarily match the scale of the drawings. Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and its equivalent scope. That is. In the same way, they are included in the scope of the invention described in the claims and its equivalent scope. That is.

Claims

1. A method for cultivating seaweeds such as kombu and wakame using a cultivation rope, comprising: installing the cultivation rope with the seaweed seeds or seedlings attached thereto in a sandy area on the seabed; growing the thalli of the seaweed by lodging them on the cultivation rope as a base.

2. The method for cultivating seaweeds according to Claim 1, wherein the sandy area is a sandy area where submarine spring water gushes out.

3. The method for cultivating seaweeds according to Claim 2, wherein the cultivation rope is installed within 1 m in the vertical direction from the sandy area.

4. The method for cultivating seaweeds according to Claim 3, wherein the thalli of the seaweed include thalli of 50 cm or more.

5. The method for cultivating seaweeds according to Claim 1, wherein the thalli of the seaweed include thalli of 50 cm or more.

6. The method for cultivating seaweeds according to Claim 5, wherein at least 50% or more of the sandy area between the cultivation rope and a distance of 50 cm from the cultivation rope is covered with the thalli of the seaweed in plan view.

7. The method for cultivating seaweeds according to Claim 1, wherein the cross section of the cultivation rope is substantially circular.

Images