JPH0241306B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing lime algae on underwater reefs, which removes the so-called rock-burning phenomenon or rock-rotting phenomenon that occurs on irregularly deformed underwater rock reefs. It is something.

In general, the phenomenon referred to by fishing industry people as rocky shore burn or rock rotting is caused by calcareous algae (a member of the coralline family, a generic term for seaweed that has a large amount of lime in its body) on underwater reefs where kelp and other plants grow. The kelp, which is supposed to grow there, becomes extremely thick, and some or all of it has decayed and its limestone remains cover the reef, giving it a white appearance.
This prevents the growth of spores of useful algae such as Tengusa and Arame on the rocks, permanently turning it into a completely barren area, and significantly reducing the yield of these algae. This phenomenon refers to a phenomenon in which the yield of spiny lobster, rockfish, etc. is significantly reduced.

Damage to kelp caused by this calcareous algae occurred in the Hokkaido coastal waters, the main producing areas of kelp, the Shimokita coastal waters of Aomori Prefecture, the Izu waters of Shizuoka Prefecture, Shimato, Mie Prefecture, Awa-to, Chiba Prefecture, and Ama District, Tokushima Prefecture. It has been reported that the disease has spread nationwide, causing a decline in the production of sugar beet, arame, and abalone, and that the trend has become particularly severe recently.

This damage control has been taken up as a serious problem regarding fisheries since the Meiji period, and for example, in 1901, at the request of the government at the time, Dr. Kichisaburo Endo wrote a report on seaweed isoyaki in the Fisheries Survey Report Volume 12, Volume 1. After that, various research studies were carried out in each damaged area, and in 1950, Dr. Tadashi Tamura published a paper titled "Importance of Isoyaki Countermeasures," and in 1952, In 2007, a long-term and wide-area survey led by Dr. Yukio Yamada was titled ``Prevention of calcareous algae growth that impedes increased production of marine products on the coast.'' However, although these are only a few examples, these research studies are aimed at elucidating the proliferation of calcareous algae from a botanical perspective. For example, only methods such as removing limestone debris by scraping the reef surface, or blasting and rehabilitating the reef, were considered. Since all of these tasks involve underwater work and are difficult, recently the construction of artificial reefs by throwing stones has become the only means of propagating kelp species. Moreover, the biggest drawback of these conventional methods is that when using scraping, it is not only difficult to work on the seabed, but also that the surface shape of the seabed reef is extremely irregular and extremely uneven. However, it is almost impossible to completely scrape away the entire area, and if blasting is used, the calcareous algae will not be completely eliminated, and if stone throwing is used, it will cause the growth of calcareous algae. There are many points that leave plenty of room for this.

To solve the problem, it is necessary to block sunlight from the calcareous algae living on the reef and prevent it from absorbing oxygen. It has to be.

Therefore, in this invention, a wrapping bag is filled with concrete, and before the concrete hardens, it is placed on the bottom of an underwater reef where lime algae are thriving, and after a certain period of time, the concrete-filled wrapping bag is peeled off from the reef. In this way, the present invention was developed with the aim of providing a method for removing lime algae on underwater reefs, which not only causes the lime algae to rot and die, but also removes the remains of the dead lime algae.

Next, one embodiment of the method for removing lime algae on underwater reefs according to the present invention will be described based on the drawings.
2 is a wrapping bag made of, for example, hemp, ie, a hemp bag, and 2 is concrete stored and filled in the hemp bag 1.

Then, the jute bag 1 is filled with concrete 2, and the concrete 2 is allowed to settle on the seabed reef while it is not hardened. Then, the concrete 2 hardens in response to the shape of the reef. That is, the surface of the reef usually has an irregular uneven shape, but since the concrete 2 is unhardened at the stage of landing on the bottom, it adapts to the uneven shape of the reef and adheres closely. The concrete 2 hardens over time and is therefore cured into a stable shape. This process is carried out continuously over the entire reef area, completely covering the reef which has become barren due to being covered with calcareous algae. In this way, the calcareous algae living on the reef are shielded from sunlight, stop absorbing oxygen, and die. According to the inventor's experiments, it took about 6 months for the plant to completely decay and die. The cement that leaked from the bottom of the jute bag 1 penetrates into the lime that adheres to the reef, which is the remains of calcareous algae, and hardens as one, and after about 6 months, it peels off from the reef.
The debris of calcareous algae hardens and adheres to the bottom, and most of it can be removed.

In addition, in order to achieve the effect of attracting fish, it is preferable to plant a pseudo tree 3 on the concrete 2 as shown in Fig. 2, and this pseudo tree 3 is made of plastic as in the conventional example. However, it does not necessarily have to be made of plastic.

Furthermore, in order to accelerate the hardening of the concrete 2, an quick-setting agent may be mixed into the concrete 2.

Further, any means may be used to sink these two jute bags 1 containing concrete to the seabed, but for example, the following equipment may be used. That is, as shown in Figure 3 A and B,
A plurality of rotatable crosspieces 5 are provided in a comb-teeth shape from opposing long sides of a rectangular frame 4 toward the center, and protrude so that their ends overlap, and a ring is attached to the wrapping portion. At the same time, a through hole is bored in a straight line on the shorter side of the frame 4, reinforcing bars 6 are inserted through the hole, and ropes 7 are suspended upward from the four corners of the frame 4. . Then, a jute bag 1 filled with concrete 2 is placed on the crosspiece 5 and suspended to the seabed, and a worker who has dived in advance guides the frame 4 to the location where it is to be installed and pulls out the reinforcing bar 6. , the crosspiece 5 rotates downward, that is, the bottom becomes open, and the jute bag 1 containing the concrete 2 placed on top of the crosspiece 5 lands on the seabed. If left in this state, it will harden over time.

Furthermore, in order to connect a plurality of jute bags 1 containing concrete 2 installed in this manner, for example, the following procedure is performed. That is, as shown in FIG. 4, small concrete blocks 9 (this concrete block 9 is assumed to have already hardened) to which connecting reinforcing bars 8 are fixed in advance are placed on the four sides of the jute bag 1, and Concrete 2 is poured and allowed to settle in an uncured state in the same manner as described above, and adjacent pieces are connected using the connecting reinforcing bars 8.

As described above, according to the method for removing lime algae on underwater reefs according to the present invention, concrete filled in jute bags is allowed to settle in an unhardened state, so no matter what shape the concrete is on the seabed, It hardens while adapting to its shape, and as a result,
Because of its close contact with the ocean floor, it can rehabilitate barren reefs that were previously thought to be impossible to rehabilitate, making it possible for kelp spores to settle on the rocks again and grow.

Furthermore, the lifted bagged concrete can be reused to create new artificial reefs as a substitute for stone throwing, which is currently being done on other sandy seabeds, and will also have the effect of increasing the production of kelp. .

[Brief explanation of drawings]

The drawings show an embodiment of the method for removing lime algae on an underwater reef according to the present invention, and FIG. 1A is a cross-sectional view, FIG. A cross-sectional view of a plant with artificial trees planted.
Fig. 3 is a perspective view of the device for sinking to the seabed; Fig. 3 shows a state in which the crosspiece is closed; Fig. 4 shows a plan view in the state in which the crosspiece is open; be. 1... Hemp bag, 2... Concrete, 3... Pseudo tree, 4... Frame, 5... Crosspiece, 6... Rebar,
7... Hanging rope, 8... Connecting reinforcing bars, 9... Concrete block.

Claims (1)

[Claims] 1. A packaging bag is filled with concrete, and before the concrete hardens, it is placed on the bottom of an underwater reef where lime algae are thick, and after a certain period of time, the concrete-filled packaging bag is peeled off from the reef. A method for removing lime algae on underwater reefs.