1. Introduction by OnBird Phu Quoc

In the purpose of extending and restoring the dead & heavily-damaged coral colonies in Phu Quoc Island, OnBird Phu Quoc has been developing a type of cement-made biorock which will become new placements for coral larvae to attach on or for us to transplant new corals onto. We have recently placed some biorocks for testing at some coral reefs in Phu Quoc. 

It’s a fact that many coral reefs in Phu Quoc are now still the healthiest coral colonies in whole Vietnam in compared to Nha Trang, Ninh Thuan, Con Dao,… and some of coral reefs in Phu Quoc have once been seen as on top in South-east Asia, now facing serious threats: irresponsible anchorage by local boat tours, overfishing with rake nets, chemical fishing, rising temperature, etc,…


2. What is biorock?

Biorock (also seacrete) is a cement-like engineering material formed when a small electric current is passed between underwater metal electrodes placed in seawater causing dissolved minerals to accrete onto the cathode to form a thick layer of limestone. This ‘accretion process’ can be used to create building materials or to create artificial ‘electrified reefs’ for the benefit of corals and other sea-life. Discovered by Wolf Hilbertz in 1976, biorock was protected by patents and a trademark which have now expired.

Coral Jungle Reef, the heathiest coral reef in Phu Quoc Island, Vietnam
Healthy corals in the Coral Jungle Reef, the healthiest coral reef in Phu Quoc Island, Vietnam


Hard corals play a crucial role in building the reef, they spread out their coral larvae into the water, coral larvae flow with the current and eventually attach on a placement, they grow up into new corals thanking to a symbiotic relationship with zooxanthellae algea which provide corals with 90% of nutrient they need.


3. Descriptions about the OnBird-developed Biorocks

We develop cement-made biorocks with holes created on the rock to hold the corals. One of the hardest things when building a biorock is to attach new corals onto them. In a usual way, divers use glue to attach new corals onto a placements above the water (wait for corals to attach tightly) before carrying them into the water.

Onbird deploy biorocks at some coral reefs in Phu Quoc Island, Vietnam
Onbird deploy biorocks with the attached holes at some coral reefs in Phu Quoc Island, Vietnam

To overcome the shortcomings we craft small holes on the rock beforehand to hold new corals instead of using glue.


Number of Bio-rocks we have lay on at the Coral Reefs in Phu Quoc Island

OnBird team lay on the bio-rocks on the sandy areas or dead coral areas and setup fish-homing bio-rock areas