We revisited our first Mineral Accretion Technology (MAT) after 2 weeks to monitor its progress. You can read our previous blog post about the MAT system installation. It goes through the installation process and technical details of our pilot site in front of our partners, the MERO Foundation, in Tulamben, East Bali.
It took many years to convince us to try Mineral Accretion Technology (MAT). Like many, we had been disappointed with the published results achieved by various organizations using this technique in their own projects. Nevertheless, being stubborn, we preferred to see for ourselves what this technique offered and if it could be a viable tool for coral restoration.
Ring Layout Of Coral Tables and Reef stars
The idea was to have a homogeneous inner ring of tables and an outer ring of Reef Stars around the Anode. Every structure of the same size is placed at the same distance from the Anode as the others, thereby receiving exactly the same electrical field and level of calcium precipitation and accretion.
The first ring of Coral Tables were designed as broodstock producing nursery racks. They were first seeded with corals from our other coral restoration nurseries around Bali, and a few corals of opportunity. When these corals grow big enough, they will be used to seed the reef stars that are on the second ring of structures. When the seeded reef stars have grown enough, they will be disconnected from the electrical current and moved to the restoration sites around the area, A new reef star will be connected and seeded with corals from the inner ring nursery racks.
So far, we have planted 354 fragments from the first pilot setup of 8 July 2025 – from 4 coral genera, 16 species of Acropora sp, Pocillopora verrucosa, Porites lutea, and Dipsastraea sp.
Only 2 weeks, but already a couple surprises!
Iron structures are sealed with calcium carbonate
While the reef stars are waiting for their seeded coral fragments to grow, they are already coated with a nice layer of Calcium Carbonate, effectively protecting them against corrosion, biofouling organisms. The Calcium Carbonate coating replaces the resin, petrochemical component coating traditionally usually used with this technique.
Tiny fragments are surviving well – no mortality
Since the donor colonies on the coral tables are new, we did not have access to many broodstock colonies and corals of opportunity yet. The selection of coral fragments for seeding was a little more challenging. We were forced to use smaller than normal fragments before the mother colonies are big enough to supply us with a decent number of proper-size fragments.
We started with 3-6 cm fragments. Usually, we don’t recommend planting such small pieces as these are not developed enough to have the necessary defence mechanisms to fight off algae, diseases, parasites. Typical very small coral fragments usually end up with a lot of mortality. We typically recommend using coral fragments of at least 10-12 cm for coral restoration. We were very pleased with the fact that all the fragments are still alive after 2 weeks, which is usually the critical recovery time. Even the smallest 3 cm fragments have attached, which in itself is already quite surprising.
Coral fragments are overgrowing metal ties
In North East Bali, we usually have very poor result using iron wire to attach corals. It often leads to bacterial infections. In Nusa Penida and its high flow rates gives a better result, but the results from iron wires are still not as good as plastic cable ties. But since with electrification, it doesn’t rust and is quickly covered by the calcium carbonate deposited on it. It becomes very neutral and the new coral tissue quickly grow on top of it.
The next few photos you can see the metal ties disappearing under the encrusting coral tissue.
New Growth is already visible at the tips
The following are a few macro shots of some of our seeded Acropora fragments. The growth of Acropora corals is largely driven by their axial corallite, a single, dominant polyp located at the tip of each branch. Typically, the new growth areas are paler as they contains fewer symbiotic algae (zooxanthellae) which gives the coral the brown coloring. Notice the pale tips as the corals are showing new growth.
Promising results so far
After just two weeks, we’re thrilled to see that many corals have already begun to overgrow their attachment wires. This is an incredibly encouraging sign, as corals typically take much longer to recover from the stress of being planted.
The conditions in Bali have been ideal for this rapid growth. During July and August, the water temperature hovers between a comfortable 27-28°C, which is perfect for coral health. We’ve also had plenty of sunny weather with no major storms in sight. This combination of optimal conditions has given the corals a head start. We will continue to monitor their progress and share updates in future posts.
