Concrete is often the material of choice when it comes to creating structures beneath the sea. For example, concrete blocks are frequently used as anchors to attach buoys and boating lines, so that boats may moor up, or as obstacles to prevent illegal fishing. Windmills and quay walls are also made of concrete. It is a well-known fact that after a number of years, concrete in the tropics become teaming with life, algae, coral, and fish find a home here. This process can take a number of years, and for us it is a challenge to find ways to speed up this process. Usually the surface of the concrete is relatively smooth, and so it therefore offers little shelter for smaller organisms.

If a coral larva seeks to find a home after fertilization, they prefer a safe place where fish cannot immediately reach them, to ensure they are not eaten. This makes a flat concrete surface unsuitable for these small coral larvae. Small crabs and shrimp also prefer to have a hole to hide in, and so the question arises: “How can we make the surface of the concrete suitable for marine life to find a cozy spot to call home?”

Twelve Concrete blocks have been made for the new structure of Suara Pulau and are placed in the water on CoralDay. We decided to make different textures on the surface of the blocks in order to test which features make the most difference. We chose four different surfaces, and made three iterations of each in order to compare the effectiveness of the different variations.

The surface of the first 3 blocks is just concrete, in which we carved grooves in order to create a rough surface.

In the next set of 3 blocks we placed dead coral skeletons, and shells. This is a beautiful natural material to which the new corals can easily attach themselves.

The third trio of blocks have been ingrained with a layer of icing sugar. We have heard rumors that the application of icing sugar onto wet concrete changes the composition of the top layer, so that coral might more easily grow upon it. Unfortunately we cannot find any scientific evidence to back this up, and so this is just a test to see if this method is effective and has any merit.

In the last three concrete blocks we have places fruit residues, skins and pits in the wet concrete. When the concrete has hardened we remove these objects, so that various intricate holes remain molded into the concrete. These holes are ideal for all sorts of small organisms, including crustaceans, coral larvae, and fish.

This is not scientifically sound research, but it is a first step. Should we discover that that these methods are effective, we will further investigate how concrete surfaces can be designed and built in such a manner as to be more hospitable to marine life, while remaining efficient and cost-effective in their production.

Do you have knowledge, experience, or ideas on how we can make the the surface of concrete more suited to foster healthy and happy marine life? Let us Know!

The real method to gain knowledge is the experiment. ”
William Blake – English poet and painter 1757-1827

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For example, SummerLabb offered its visitors a look into a sustainable future. The visitors got an extensive story about platics soup and how you can reduce your own plastic footprint yourself. This went from the use of BioPlastic to a laundry bag to filter your plastic and nylon microfibers, which are released when washing synthetic clothes. There was also promotion for lead-free fishing (Dutch) and how to design your garden to absorb more rainwater.

Several coral experts were present and companies involved in the cultivation of seaweed and mats to grow oysters. Jan Douwe Kroeske interviewed Vera Aarden about CoralGardening’s vision on the future of coral reefs.

Besides a shows with mermaids, there was also the world record “rings blowing” improved by freediver Jorrit Bruinsma. He could blow 71 rings in 2 minutes 18, on one breath. The whole record attempt can be seen here.

Children could have fun at our stand with the workshop CoralGardening. This time it was even possible to make the designs in color. After claying  the house for fishes, they could paint the works in desired colors. This makes them even more beautiful after baking.

Of course we informed everyone with photos, videos and personal stories of Willem, Arjan, Vera and Frank about the construction of the CoralGarden on Koh Tao. More people have interest to assist us in building the CoralGarden on location. If you are interested in building with us, please send us an e-mail. Would you rather build from your home country? That is also possible! On our donation page you can donate, so we can buy the necessary materials on site.

Furthermore Marcel Coret from Diving School KevMic-Diving came to our booth to hand over our regulators after a thorough service. Marcel, thank you so much for the good and fast service!

Several companies offered to sponsor CoralGardening, but more about that later.

Thank you very much for your visit, interest and donations!

An impression of the Duikvaker made by Bas:

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The local action group Get Involved Koh Tao every month organizes an EcoDay and is active to persuade bars to stop using plastic straws and plastic cups. On EcoDay many divers, freedivers and tourists from different diveschools come together to get a morning full of education with presentations and documentaries. In the afternoon the group is split up to do a beach clean-up, a reef clean-up and join building or assembling the new artificial reef under water.

We know the drill of building a flower underwater with divers, but freediving is quiet a bit different. Bringing parts of structures down with freedivers has been done before. And now is the next challenge, assembling the flower. A pair of two freedivers take a deep breath, go down and assemble a piece of the flower. When you “run out of air”, you go up and do your recovery breath. On the surface your buddy keeps an eye out for your safety. Then the next pair goes down and assembles the next leaf, etcetera. Sometimes it takes longer to put a piece in the flower, so when you can’t hold your breath any longer you have to leave it for the next team. It is great fun to work on the flower as a team. Great for the team spirit as well!

All the freedivers had to go down many times. When they came back on the boat, they were really exhausted. But I will never forget the smiles on their faces!

Thanks to Blue Immersion for their involvement creating a few flowers on our workplace and assembling the flower under water. Big thanks to Ocean Candy for the beautiful video!

Thank you for all (divers and freedivers) who participated in this amazing achievement! It was great to have one big boat full of dive enthusiasts sharing this experience with different dive methods. Wonderful to see we all share the same passion!

And of course thanks to our local partners on Koh Tao and the sponsors and donators from all over the world. Thank you to all who make this possible!

Subscribe to our YouTube channel to see the video of planting the flower.

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