JP3915676B2 - How to install an aquatic substrate for aquatic organisms - Google Patents
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Description
【０００１】
【発明が属する技術分野】
本発明は、海藻や珊瑚等のような水中生物を着生させるべき着生基質（基盤）を水中に設置する方法に関するもので、海藻や珊瑚等を基質に効果的に着生させることができ、特に藻場（藻礁）や珊瑚礁等の造成・修復に好適な方法を提供するものである。
【０００２】
【従来の技術】
ホンダワラ類やアラメ、カジメ、コンブ等の海藻が群落する藻場は沿岸海域における海中動植物の生産の場であり、有用魚介類や海藻の生息場、魚介類の産卵場、稚仔魚の成育場、餌場等として不可欠な場所であると言える。また最近では、海水中の窒素やリンが海藻に取り込まれ或いは藻場内の食物連鎖を通じて他の生物に取り込まれることにより除去されることや、藻場内で懸濁物質が沈降して水中から取り除かれることなど、藻場の水質浄化作用についても注目されつつある。
【０００３】
しかし、近年、藻場は沿岸の埋め立てや海水の汚濁などの影響により急速な消失、衰退が続いており、特に最近では、多くの沿岸海域で所謂“磯焼け”と呼ばれる現象が発生し、大きな問題となっている。このため最近では、消失、衰退した藻場を回復させるための対策（藻場造成）が各地で行われるようになってきた。
従来行われている藻場造成の手法の一つに、藻場を造成したい場所に、海藻を育成するための基質（通常、コンクリートブロック等）を設置して、この基質に海藻の種苗や母藻を移植し、必要に応じて海藻育成のためのメンテナンスを行う方法がある。しかし、この方法は基質への種苗の移植や基質設置後のメンテナンスに手間と費用がかかり、大規模な藻場造成には適していない。したがって、藻場造成の基本的な手法としては、基質を種苗の移植等を行うことなくそのまま藻場造成場所に設置し、且つ設置した後はメンテナンスフリーで海藻を着生・生育させることが必要があると考えられる。
【０００４】
【発明が解決しようとする課題】
従来、藻場造成場所に設置される着生基質としては、製造の容易さ、海中での安定性、製造コスト等の面からコンクリートブロックが広く用いられている。しかし、コンクリートブロックを着生基質として単に海底に設置しても、十分満足できるような量の海藻を着生・生育させることができないという問題がある。このためブロックの基質面に凹凸や溝を付けたり、着生促進物質を塗布又は添付したり、或いは基質中に着生促進物質を添加するといった海藻着生を促す対策（例えば、特許文献１、特許文献２、非特許文献１）も試みられているが、その効果は必ずしも明確でなく、また、着生促進を目的として基質面に特別な加工や処理を加えたり、基質中に着生促進物質を添加したりすることは、藻場造成のコスト面からも問題がある。
【０００５】
【特許文献１】
特開２００１−２７５５０６号公報
【特許文献２】
特開２００２−４５０８０号公報
【非特許文献１】
「第５４回セメント技術大会講演要旨 ２０００」p．４１０−４１１
【０００６】
したがって本発明の目的は、基質面に着生促進のための特別な処理や加工を施したり、基質中に着生促進物質を添加したりしなくても、水中に設置した着生基質に海藻や珊瑚等の水中生物を効果的に着生・生育させることができる着生基質の設置方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明者らは、海中に設置された着生基質面に海藻等の遊走子や卵等が着生して幼体まで成長するための諸条件について検討を行う過程で、着生基質表面に形成される境界層に着目し、この境界層が海藻等の遊走子や卵の着生・生育に及ぼす影響について詳細な実験と検討を行った。その結果、この着生基質表面に存在する海水の微小環境域（境界層）が海藻の遊走子や卵の着生・生育に大きく関与していることが判った。すなわち、海藻の繁殖形態は、胞子体（親個体）から放出された遊走子や卵が海水中を浮遊して基質に到達し、その表面に着生した後、幼体、さらには胞子体へと成長するものであるが、遊走子や卵が基質表面に到達した際に基質表面に適切な厚さの境界層が形成されていると、遊走子や卵が境界層の中に取り込まれ（すなわち基質表面から再離脱しない）、この境界層が遊走子や卵が着生・生育する環境（領域）となる。そして、境界層の水質は基質自体の組成や性質に大きく支配されるため、基質の組成や性質により境界層の水質環境が遊走子や卵の着生・生育に適したものであれば、境界層内の遊走子や卵は基質表面に適切に着生し、生育することになる。すなわち、基質表面に遊走子や卵を適切に着生させ、幼体まで生育させるには、基質に到達した遊走子や卵を取り込むことができる適切な厚さを有し、且つそれらの着生・生育に適した水質環境を有する境界層を基質表面に形成させる必要があることが判った。そして、そのような境界層を形成するための方策についてさらに検討を進めた結果、基質として所定レベル以下のｐＨを有するものを用いるとともに、その基質を、着生させるべき生物の遊走子や卵等の直径以上の厚さの境界層が形成されるような海中環境下に設置することが必要であることが判った。
【０００８】
本発明はこのような知見に基づきなされたもので、その特徴は以下の通りである。
［1］水中の基質に着生して成長する生物用の着生基質を水中に設置する方法において、
着生基質表面に着生・生育させるべき生物の遊走子、卵又は幼生の直径Ｄ（但し、遊走子、卵又は幼生が球形でない場合はその長径）を特定するとともに、水の動粘性率ν（ｍ ２ ／ sec ）と、着生基質を設置した場合の水の流れ方向における着生基質上部面の長さの１／２の値ｘ（ｍ）と、着生基質設置場所における水の最大流速Ｕ ０ （ｍ／ sec ）を計測するステップと、
ｐＨ１０以下の着生基質を水中に設置するに当たり、下記(1)式で規定される着生基質の上部面に形成される境界層の厚さδが、前記直径Ｄとの関係で下記(2)式の条件を満足するよう、着生基質の設置場所を選定し又は着生基質の設置場所の水の流速を人工的に制御するステップを有することを特徴とする水中生物用の着生基質の設置方法。
【数２】
［2］上記［1］の設置方法において、着生基質がｐＨ７．５〜９．５であることを特徴とする水中生物用の着生基質の設置方法。
［3］上記［1］又は［2］の設置方法において、着生基質表面に着生・生育させるべき生物が、海藻、珊瑚、貝類、フジツボ類、ゴカイ類の中から選ばれる１種以上であることを特徴とする水中生物用の着生基質の設置方法。
［4］上記［1］〜［3］のいずれかの設置方法において、着生基質が、カルシウム成分として実質的に炭酸カルシウムのみを含むことを特徴とする水中生物用の着生基質の設置方法。
【００１０】
【発明の実施の形態】
以下、本発明による水中生物用の着生基質の設置方法の詳細と好ましい実施形態について説明する。なお、以下においては、着生基質を海中に設置する場合を例に説明する。
本発明は、着生基質を海中に設置するに当たり、着生基質の表面に海藻等の遊走子や卵を取り込み且つこれらを適切に着生・生育させることができる微小環境領域、すなわち特定の厚さと水質を有する境界層を形成することを狙いとしている。
【００１１】
このため本発明では、まず、着生基質としてｐＨ１０以下の基質を用いる。
通常の海水のｐＨは７．８〜８．４程度の弱アルカリであるが、そのｐＨが１０を超えると遊走子や卵の着生や生育が著しく阻害される。ここで、着生基質表面に形成される境界層は、基質に接する流動性が低い微小厚の海水層であるため、そのｐＨは基質自体のｐＨと略同じになり、したがって、境界層のｐＨを遊走子や卵の着生・生育に適したｐＨ１０以下とするには、ｐＨ１０以下の着生基質を用いる必要がある。図１は、ｐＨ１０の基質とｐＨ１２の基質について、基質−境界層−境界層外のｐＨの遷移の概略を示したものである。一般のコンクリートのｐＨは略１２であり、したがってコンクリート製の基質表面に形成される境界層も略ｐＨ１２となり、この境界層は遊走子や卵が極めて着生・生育しにくい環境であると言える。また、本発明で用いる着生基質のより好ましいｐＨは７．５〜９．５であり、これにより境界層のｐＨも略同じｐＨとなる。
【００１２】
さらに、着生基質表面に形成される境界層の条件としては、境界層の厚さが基質に着生・生育させるべき生物の遊走子や卵等の直径よりも大きいことが必要であり、具体的には、下記(1)式で規定される、着生基質の上部面に形成される境界層の厚さδが、着生基質表面に着生・生育させるべき生物の遊走子、卵又は幼生の直径Ｄとの関係で下記(2)式の条件を満足するよう、着生基質を海中に設置することが必要である。なお、後述するように境界層の厚さは遊走子や卵等をその内部に完全に取り込むための条件として規定されるものであるため、遊走子、卵又は幼生が球形でない場合は、その長径をもって上記直径Ｄとする。
【数３】
本発明において、境界層の厚さδを上記(2)式のように規定するのは、海水の流れに乗って着生基質表面に到達した遊走子や卵などが、再び海水の流れに乗って着生基質表面から離脱せず、着生基質表面に確実に留まるようにするには、遊走子や卵の全体が完全に取り込まれるような厚さの境界層が存在する必要があるからである。着生基質表面の境界層は流動性が低い海水層であり、その内部に完全に取り込まれた遊走子や卵は、着生するまでの間にそこに留まる確率が非常に高くなる。これに対して、境界層の厚さが上記(2)式を満足しないと、遊走子や卵は境界層外の海水流の影響を受けて、着生基質表面から離脱する確率が高まる。
また、遊走子や卵の取り込みが確実に行われるという観点からは、境界層は遊走子や卵の直径Ｄに対して十分に大きい厚さを有すること、例えば、δ≧２Ｄ、さらにはδ≧３Ｄというような十分な厚さを有することが好ましい。
【００１４】
図２は、上記(1)式で規定される境界層の厚さδを示している。ここで、上記(1)式自体は境界層厚さを求めるための広く知られた式であるが、ｘを海水の流れ方向における着生基質上部面の長さの１／２としたのは、少なくとも着生基質上部面の半分に(2)式を満足する境界層を形成させるためである。
【００１５】
本発明により着生基質表面に着生・生育させるべき海中生物の代表例としては、海藻、珊瑚、貝類、フジツボ類、ゴカイ類などがあるが、これらに限定されない。海藻として対象となるのは主に岩礁性藻場を形成する海藻類であり、例えば、マコンブ、アラメ、カジメ、ワカメ等のコンブ目；アカモク、ヤツマタモク、ノコギリモク等のホンダワラ類；マクサ（テングサ）；アナアオサなどが挙げられる。
【００１６】
海藻は、その種類によって親個体から海中に放出される生殖細胞の種類や大きさが異なる。すなわち、アラメ、カジメ、コンブ等のコンブ目では、胞子体（親個体）から長径約５μｍ程度の遊走子が海中に放出され、この遊走子が基質に着生して雌雄の配偶体へと成長し、その雌配偶体で作られた卵が受精することにより幼体、胞子体へと成長する。したがって、この種の海藻を着生基質に着生・生育させる場合には、上記(2)式を満足する境界層厚さδは、海藻の種類に応じて５μｍ以上の厚さとする必要がある。
【００１７】
一方、ホンダワラ類では、胞子体（親個体）から直径約２００〜３００μｍ程度の卵が海中に放出されて海中で受精し、その受精卵が基質に着生して幼体、胞子体へと成長する。したがって、この種の海藻を着生基質に着生・生育させる場合には、上記(2)式を満足する境界層厚さδは、海藻の種類に応じて２００〜３００μｍ以上の厚さとする必要がある。
さらに、珊瑚の場合には、親個体から放出された卵（直径約５００〜７００μｍ）が海中で受精し、その受精卵から長径約２ｍｍ弱程度の幼生（プラヌラ幼生）が生まれ、この幼生が基質に着生（定着）して親個体へと成長する。したがって、珊瑚を着生基質に着生（定着）・生育させる場合には、上記(2)式を満足する境界層厚さδは、珊瑚の種類に応じて２ｍｍ以上の厚さとする必要がある。
【００１８】
上記(1)式で規定される境界層の厚さを制御するための制御因子は、着生基質の設置場所における海水の最大流速Ｕ０であり、したがって、海水の最大流速Ｕ０が上記(2)式を満足する境界層厚さδが得られるような値となる場所を着生基質の設置場所として選定するか、或いは着生基質の設置場所における海水の最大流速Ｕ０を上記(2)式を満足する境界層厚さδが得られるような流速に人工的に制御すればよい。後者の場合には、例えば、設置した着生基質又は着生基質群の周囲に海水流の抵抗となる抵抗体（例えば、板状の抵抗体）を設ける、着生基質又は着生基質群を海水流の抵抗となる通水性のある被覆材で覆う等の方法を採ることができる。
なお、本発明は海だけでなく、湖沼や川などの淡水或いは汽水域での着生基質の設置にも適用できる。
【００１９】
以下、本発明の好ましい条件について説明する。
先に述べたように、一般のコンクリートのｐＨは略１２であり、これを着生基質とした場合の境界層のｐＨも略１２となり、この境界層は遊走子や卵が極めて着生・生育しにくい環境となる。さらに、コンクリートは未炭酸化Ｃａを多量に含んでいるため、これを着生基質として水中に設置した場合、表層に水酸化カルシウムが生成して境界層内にＣａイオンが溶出し、このＣａイオンは境界層内の炭酸ガスと反応して炭酸カルシウムを生成する。この結果、境界層内で遊走子や卵の着生・生育（光合成）に必要な炭酸ガスが不足し、この面でも遊走子や卵の着生・生育が阻害されるとともに、生成した炭酸カルシウムが境界層内の遊走子や卵、基質面に付着することにより、遊走子や卵の着生・生育に悪影響を及ぼす。また、コンクリートの表層に生成した水酸化カルシウムの層は、Ｃａイオンの溶出などによって物理的にも不安定である。したがって、本発明の着生基質としては、一般のコンクリートは適さない。
【００２０】
本発明で用いる着生基質としては、カルシウム成分として実質的に炭酸カルシウムのみを含む（すなわち、不可避的に含まれる未炭酸化Ｃａを除くカルシウム成分の全量が炭酸カルシウムからなる）、ｐＨ１０以下（好ましくは、ｐＨ７．５〜９．５）の基質が特に好ましい。このような着生基質としては、例えば、粉粒状原料を適当なバインダー成分でブロック化したブロック体などが挙げられるが、これに限定されるものではない。このような着生基質を用いることにより、境界層のｐＨを１０以下（好ましくは７．５〜９．５）に維持できるとともに、基質からＣａイオンが溶出することもないので、境界層内の炭酸ガス濃度も遊走子や卵の生育に適したレベルに維持することができる。また、基質表面で新たに炭酸カルシウムが生成することもなく、しかも着生基質が元々含有している炭酸カルシウムは物理的に安定しているため、着生・生育しようとする遊走子や卵の保護にも有効である。
【００２１】
本発明によれば、基質に着生促進のための特別な処理や加工を施さなくても、着生基質に海藻や珊瑚等を効果的に着生・生育させることができるが、例えば、基質面に着生促進のための処理（例えば、着生促進物質の塗布や添付等）や加工（例えば、凹凸加工や溝加工等）を施したり、基質に着生促進物質を添加したりすることを排除するものではない。
以上述べたような本発明法により設置された着生基質は、海藻や珊瑚等のような水中生物を短期間で効果的に着生・生育させることができ、このため短期間で藻場や珊瑚礁等の造成・修復を行うことができる。
【００２２】
【発明の効果】
以上述べた本発明によれば、基質面に着生促進のための特別な処理や加工を施したり、基質に着生促進物質を添加したりしなくても、水中に設置した着生基質に海藻類や珊瑚等を効果的に着生・生育させることができる。
【図面の簡単な説明】
【図１】ｐＨ１０の基質とｐＨ１２の基質を水中に設置した場合似おける、基質−境界層−境界層外のｐＨの遷移の概略を示す説明図
【図２】本発明の(1)式で規定される境界層厚さδを示す説明図[0001]
[Technical field to which the invention belongs]
TECHNICAL FIELD The present invention relates to a method for placing an aquatic substrate (base) on which aquatic organisms such as seaweed and coral are to be established in water, and can effectively cause seaweed and coral and the like to grow on the substrate. In particular, the present invention provides a method suitable for the creation and restoration of seaweed beds (algae reefs) and coral reefs.
[0002]
[Prior art]
The seaweed ground where seaweeds such as Honda Walla, Alame, Kajime, and Kombu colonize is a place for the production of marine flora and fauna in the coastal waters, habitats for useful seafood and seaweeds, spawning grounds for seafood, larvae It can be said that it is an indispensable place as a feeding ground. Recently, nitrogen and phosphorus in seawater are removed by being taken up by seaweeds or by other organisms through the food chain in the seaweed beds, and suspended substances are settled and removed from the water in the seaweed beds. Attention is also being paid to the water purification effect of the algae ground.
[0003]
However, in recent years, seaweed beds have been rapidly disappearing and declining due to the effects of coastal land reclamation and seawater pollution, and in recent years, a so-called “burning” phenomenon has occurred in many coastal waters, causing a large It is a problem. For this reason, recently, countermeasures (reconstruction of seaweed beds) to recover lost and declined seaweed beds have been carried out in various places.
One of the conventional methods for creating seaweed beds is to install a substrate (usually a concrete block, etc.) for growing seaweed at the place where you want to create the seaweed plateau, and to this substrate, seaweed seedlings and mothers There is a method of transplanting algae and performing maintenance for growing seaweed as necessary. However, this method requires time and effort for transplanting seedlings to the substrate and maintenance after the substrate is installed, and is not suitable for large-scale algae bed construction. Therefore, as a basic method for creating seaweed beds, it is necessary to install the substrate as it is in the place where the seedlings are created without transplanting seedlings, and after that, it is necessary to grow and grow seaweed without maintenance. It is thought that there is.
[0004]
[Problems to be solved by the invention]
Conventionally, a concrete block has been widely used as an epidemic substrate to be installed at a place where a seaweed bed is created, in terms of ease of production, stability in the sea, production cost, and the like. However, there is a problem that even if a concrete block is used as an epiphytic substrate on the sea floor, a sufficient amount of seaweed cannot be established and grown. For this reason, measures to promote seaweed formation such as adding irregularities or grooves to the substrate surface of the block, applying or attaching an adhesion promoting substance, or adding an adhesion promoting substance to the substrate (for example, Patent Document 1, Patent Document 2 and Non-Patent Document 1) have also been tried, but the effect is not always clear, and special processing or treatment is added to the substrate surface for the purpose of promoting the growth, or the growth is promoted in the substrate. Adding a substance also has a problem in terms of the cost of creating a seaweed bed.
[0005]
[Patent Document 1]
JP 2001-275506 A [Patent Document 2]
JP 200245080 A [Non-Patent Document 1]
“Summary of the 54th Cement Technology Conference 2000” p. 410-411
[0006]
Therefore, an object of the present invention is to provide a seaweed to an epiphytic substrate installed in water without performing special treatment or processing for promoting epitaxy on the substrate surface or adding an epithelial promoting substance to the substrate. An object of the present invention is to provide a method for installing an epitaxy substrate that can effectively grow and grow aquatic organisms such as fish and cocoons.
[0007]
[Means for Solving the Problems]
In the process of examining various conditions for the growth of zoospores and eggs such as seaweed and the like to grow up to juveniles on the surface of the epiphytic substrate installed in the sea, the present inventors formed on the epithelial substrate surface. Focusing on the boundary layer, we conducted detailed experiments and studies on the effect of this boundary layer on the growth and growth of zoospores and eggs such as seaweed. As a result, it was found that the microenvironmental area (boundary layer) of seawater existing on the surface of this epiphytic substrate is greatly involved in the epiphytic growth and growth of seaweed zoospores and eggs. In other words, the seaweed breeding form is that the zoospores and eggs released from the spore body (parent individual) float in the seawater, reach the substrate, and settle on the surface, then the young body and then the spore body. It grows, but when the zoospores and eggs reach the substrate surface, if a boundary layer of appropriate thickness is formed on the substrate surface, the zoospores and eggs are taken into the boundary layer (i.e. This boundary layer becomes an environment (region) where zoospores and eggs grow and grow. And since the water quality of the boundary layer is largely governed by the composition and properties of the substrate itself, if the water quality environment of the boundary layer is suitable for the growth and growth of zoospores and eggs due to the composition and properties of the substrate, the boundary The zoospores and eggs in the layer will properly grow and grow on the substrate surface. In other words, in order to properly establish zoospores and eggs on the substrate surface and to grow to juveniles, it has an appropriate thickness that can take up the zoospores and eggs that have reached the substrate, and the It was found that a boundary layer having a water quality environment suitable for growth needs to be formed on the substrate surface. Then, as a result of further investigation on the measures for forming such a boundary layer, a substrate having a pH of a predetermined level or less is used as a substrate, and the substrate is a zoospore or egg of an organism to be grown. It was found necessary to install in an underwater environment where a boundary layer with a thickness greater than the diameter of the boundary layer is formed.
[0008]
The present invention has been made based on such findings, and the features thereof are as follows.
[1] In a method of installing an epiphytic substrate for living organisms that grow on a submerged substrate in water,
The diameter D of a zoospore, egg or larva of an organism to be grown and grown on the surface of the substrate is specified (however, if the zoospore, egg or larva is not spherical), the kinematic viscosity of water ν (M 2 / sec ), a value x (m) that is half the length of the upper surface of the substrate in the direction of water flow when the substrate is installed, and the maximum amount of water at the site where the substrate is installed Measuring the flow velocity U 0 (m / sec );
Upon installing pH10 following epiphytic substrate in water, the following (2 with a thickness of the boundary layer formed on the upper surface of the epiphytic substrate defined by the following (1) equation δ is, the relationship between the diameter D The substrate for aquatic organisms is characterized in that it has a step of artificially controlling the flow rate of water at the site where the substrate is installed , so as to satisfy the condition of the formula Installation method.
[Expression 2]
[2] The method for installing an aquatic substrate for aquatic organisms according to the above [1], wherein the substrate is pH 7.5 to 9.5.
[3] In the installation method of [1] or [2] above, the organism to be grown and grown on the surface of the substrate is at least one selected from the group consisting of seaweed, coral, shellfish, barnacles, and cormorants. An installation method for an aquatic substrate for aquatic organisms.
[4] In the installation method according to any one of the above [1] to [3], the settlement substrate includes substantially only calcium carbonate as a calcium component. .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details and preferred embodiments of the method for installing an aquatic substrate according to the present invention will be described. In the following description, an example in which the substrate is installed in the sea will be described.
The present invention provides a microenvironment region that can take in zoospores and eggs such as seaweed on the surface of the substrate and allow them to properly grow and grow when the substrate is placed in the sea, that is, a specific thickness. The aim is to form a boundary layer with water quality.
[0011]
For this reason, in the present invention, first, a substrate having a pH of 10 or less is used as the substrate for formation.
The pH of normal seawater is a weak alkali of about 7.8 to 8.4, but if the pH exceeds 10, the establishment and growth of zoospores and eggs are significantly inhibited. Here, since the boundary layer formed on the surface of the substrate is a micro-thick seawater layer with low fluidity in contact with the substrate, its pH is substantially the same as the pH of the substrate itself, and therefore the pH of the boundary layer In order to adjust the pH to 10 or less suitable for the growth and growth of zoospores and eggs, it is necessary to use an incubation substrate with pH 10 or less. FIG. 1 shows an outline of the pH transition between the substrate-boundary layer and the boundary layer for a pH 10 substrate and a
[0012]
Furthermore, as a condition of the boundary layer formed on the surface of the epiphytic substrate, the thickness of the boundary layer needs to be larger than the diameter of a zoospore or egg of an organism to be grown and grown on the substrate. Specifically, the thickness δ of the boundary layer formed on the upper surface of the epiphytic substrate, defined by the following formula (1), is the zoospore, egg or In order to satisfy the condition of the following formula (2) in relation to the diameter D of the larva, it is necessary to install an epiphytic substrate in the sea. As will be described later, the thickness of the boundary layer is defined as a condition for completely taking in zoospores, eggs, etc., so if the zoospore, egg or larva is not spherical, its long diameter Is the diameter D.
[Equation 3]
In the present invention, the thickness δ of the boundary layer is defined as in the above equation (2) because the zoospores and eggs that have reached the surface of the substrate by riding on the flow of seawater get on the flow of seawater again. In order to ensure that they remain on the surface of the substrate without being detached from the surface of the substrate, there must be a boundary layer that is thick enough to completely capture the entire zoospore or egg. is there. The boundary layer on the surface of the substrate is a low-fluidity seawater layer, and the probability that the zoospores and eggs that have been completely taken into the substrate will stay there until they settle. On the other hand, if the thickness of the boundary layer does not satisfy the above equation (2), the probability that the zoospores and eggs are detached from the surface of the substrate is affected by the seawater flow outside the boundary layer.
Further, from the viewpoint of surely taking up zoospores and eggs, the boundary layer has a sufficiently large thickness with respect to the diameter D of the zoospores and eggs, for example, δ ≧ 2D, and further δ ≧ It is preferable to have a sufficient thickness such as 3D.
[0014]
FIG. 2 shows the thickness δ of the boundary layer defined by the above equation (1). Here, the above equation (1) itself is a well-known equation for obtaining the boundary layer thickness, but x is set to 1/2 of the length of the upper surface of the substrate in the seawater flow direction. This is because a boundary layer satisfying the formula (2) is formed on at least half of the upper surface of the substrate.
[0015]
Representative examples of marine organisms to be grown and grown on the surface of the substrate according to the present invention include, but are not limited to, seaweed, coral, shellfish, barnacles, and coral. The seaweeds are mainly seaweeds that form reef-type seaweed beds, for example, macaques, arame, kajime, seaweeds, etc .; Anaaaosa and so on.
[0016]
Seaweeds differ in the type and size of germ cells released into the sea from their parents. In other words, zoospores such as arame, kajime, and kombu, zoospores having a major axis of about 5 μm are released from the spores (parent individuals) into the sea, and the zoospores grow on the substrate and grow into male and female gametophytes. However, the eggs made from the female gametophytes grow into fertile and spore bodies by fertilization. Therefore, when this type of seaweed is grown and grown on the substrate, the boundary layer thickness δ satisfying the above equation (2) needs to be 5 μm or more depending on the type of seaweed. .
[0017]
On the other hand, in the species of Honda, eggs having a diameter of about 200 to 300 μm are released from the spore body (parent individual) into the sea and fertilized in the sea, and the fertilized egg settles on a substrate and grows into a young body or a spore body. . Therefore, when this type of seaweed is grown and grown on the substrate, the boundary layer thickness δ satisfying the above equation (2) needs to be 200 to 300 μm or more depending on the type of seaweed. There is.
Furthermore, in the case of a pupa, an egg (diameter of about 500 to 700 μm) released from a parent individual is fertilized in the sea, and a larva (planar larva) having a major axis of about 2 mm or less is born from the fertilized egg. It grows into a parent individual. Therefore, when the cocoon grows (fixes) and grows on the substrate, the boundary layer thickness δ that satisfies the above equation (2) needs to be 2 mm or more depending on the type of cocoon. .
[0018]
The control factor for controlling the thickness of the boundary layer defined by the above equation (1) is the maximum flow velocity U 0 of seawater at the place where the substrate is placed. Therefore, the maximum flow velocity U 0 of seawater is the above ( The location where the boundary layer thickness δ satisfying the equation (2) is obtained is selected as the installation location of the epidermal substrate, or the maximum seawater flow velocity U 0 at the epithelial substrate installation location is the above (2 The flow rate may be artificially controlled so as to obtain the boundary layer thickness δ satisfying the equation (1). In the latter case, for example, an epithelial substrate or a group of epithelial substrates provided with a resistor (for example, a plate-shaped resistor) that provides resistance to seawater flow around the installed epithelial substrate or group of epithelial substrates. It is possible to adopt a method such as covering with a water-permeable covering material that becomes resistance to seawater flow.
Note that the present invention can be applied not only to the sea, but also to the installation of epiphytic substrates in fresh water or brackish water areas such as lakes and rivers.
[0019]
Hereinafter, preferable conditions of the present invention will be described.
As described above, the pH of general concrete is approximately 12, and the pH of the boundary layer when this is used as an epiphytic substrate is also approximately 12, and in this boundary layer, zoospores and eggs are extremely settled and grown. It becomes an environment difficult to do. Furthermore, since concrete contains a large amount of uncarbonated Ca, when it is placed in water as an epiphytic substrate, calcium hydroxide is generated in the surface layer and Ca ions are eluted in the boundary layer. Reacts with carbon dioxide in the boundary layer to produce calcium carbonate. As a result, the carbon dioxide required for the growth and growth (photosynthesis) of zoospores and eggs in the boundary layer is insufficient, and the growth and growth of zoospores and eggs are also inhibited in this aspect, and the generated calcium carbonate Adhering to zoospores, eggs, and substrate surfaces in the boundary layer adversely affects the growth and growth of zoospores and eggs. Moreover, the calcium hydroxide layer formed on the concrete surface layer is physically unstable due to elution of Ca ions and the like. Therefore, general concrete is not suitable as the curing substrate of the present invention.
[0020]
The epidermal substrate used in the present invention contains substantially only calcium carbonate as a calcium component (that is, the total amount of calcium components excluding unavoidable uncarbonated Ca is composed of calcium carbonate), and has a pH of 10 or less (preferably Is particularly preferably a substrate having a pH of 7.5 to 9.5). Examples of such an adherent substrate include, but are not limited to, a block body obtained by blocking a powdery raw material with an appropriate binder component. By using such a substrate, the pH of the boundary layer can be maintained at 10 or less (preferably 7.5 to 9.5), and Ca ions are not eluted from the substrate. The carbon dioxide concentration can also be maintained at a level suitable for growth of zoospores and eggs. In addition, no calcium carbonate is newly generated on the surface of the substrate, and the calcium carbonate originally contained in the substrate is physically stable. It is also effective for protection.
[0021]
According to the present invention, it is possible to effectively grow and grow seaweed, cocoons and the like on the substrate without subjecting the substrate to special treatment or processing for promoting the growth. Apply surface treatment (for example, application or attachment of a growth promoting substance) or processing (for example, uneven processing or groove processing), or add a growth promoting substance to the substrate. Is not to be excluded.
The epiphytic substrate installed by the method of the present invention as described above can effectively establish and grow aquatic organisms such as seaweed and coral in a short period of time. Can create and restore coral reefs.
[0022]
【The invention's effect】
According to the present invention described above, it is possible to apply the treatment to the substrate set in water without performing any special treatment or processing for promoting the growth on the substrate surface or adding the material for promoting the growth to the substrate. Seaweeds and corals can be effectively grown and grown.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of pH transition between a substrate, a boundary layer, and an outside boundary layer, which is similar when a substrate having a pH of 10 and a substrate having a pH of 12 are installed in water. FIG. Explanatory diagram showing the defined boundary layer thickness δ
Claims (4)
着生基質表面に着生・生育させるべき生物の遊走子、卵又は幼生の直径Ｄ（但し、遊走子、卵又は幼生が球形でない場合はその長径）を特定するとともに、水の動粘性率ν（ｍ ２ ／ sec ）と、着生基質を設置した場合の水の流れ方向における着生基質上部面の長さの１／２の値ｘ（ｍ）と、着生基質設置場所における水の最大流速Ｕ ０ （ｍ／ sec ）を計測するステップと、
ｐＨ１０以下の着生基質を水中に設置するに当たり、下記(1)式で規定される着生基質の上部面に形成される境界層の厚さδが、前記直径Ｄとの関係で下記(2)式の条件を満足するよう、着生基質の設置場所を選定し又は着生基質の設置場所の水の流速を人工的に制御するステップを有することを特徴とする水中生物用の着生基質の設置方法。
The diameter D of the zoospores, eggs or larvae of the organism to be grown / grown on the surface of the growth substrate (however, if the zoospores, eggs or larvae are not spherical), the kinematic viscosity ν of water (M 2 / sec ), a value x (m) that is half the length of the upper surface of the substrate in the direction of water flow when the substrate is installed, and the maximum amount of water at the site where the substrate is installed Measuring the flow velocity U 0 (m / sec );
Upon installing pH10 following epiphytic substrate in water, the following (2 with a thickness of the boundary layer formed on the upper surface of the epiphytic substrate defined by the following (1) equation δ is, the relationship between the diameter D The substrate for aquatic organisms is characterized in that it has a step of artificially controlling the flow rate of water at the site where the substrate is installed , so as to satisfy the condition of the formula Installation method.
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