Making bottle reefs for coral planting

Preparation of the moulds

Artificial Reef preparation and construction is an ongoing process at TRACC, some part of the process happens for 6 from the 7 days of the week.

This week, our Malaysian staff and volunteers were building more bottle reefs in the moulds. The moulds are lined with plastic to stop the cement sticking to the wooden sides or becoming dry by losing all the moisture down into the sand floor. Each mould is about 10ft long, made of a wooden frame. The cement is mixed by the very nice new mixer bought with the support of the Small Grants Programme of the Global Environment Facility (SGP/GEF). The mixture of sand and cement is a wet mortar and we use a plasticizer to give the mixture more workability. The sloppy mortar mixture is poured into the moulds and then the bottles can be added.

Bottle reefs waiting for the cement to set overnight.

Each bottle is pre-cleaned to remove the labels and any residue of contents. We only use bottles which have contained food or drink so that there is no risk of pollution from the bottle contents.

The bottles are rolled in the wet cement mortar so that they have a slightly roughened surface from the cement and sand. When this layer is hard it helps the attraction and settlement of a wide variety of sedentary reef building organisms such as sponges, ascidians byozoans as well as hard and soft corals.

The bottles are worked into the bed of mortar so that they stand upright and are submerged by 3-5 cm in the wet mortar. Generally the bottles are positioned about 7-12 cm apart. If they are too close then it is hard to make the block so that it doesn't fall apart when it is set. If the bottles are too far apart, then the coral fragments or biscuits could move out of the protective ring of bottles and fall into the sand. All sizes and shapes of bottles can be used; from jamjars to ketchup to beer bottles.

finished bottle reefs after the cement has set.

Plastic water bottles are not normally used because they can come out of the cement base when there is wave action. Fizzy drink bottles can be used but we puncture holes near the base so that the cement mortar goes into the bottles and helps to lock them into the bottle reef block. Most of the bottle reefs for coral planting use only glass bottles which are not in short supply. Glass is not recycled in Sabah because of the cost of shipping to Peninsular Malaysia. Consequently there are plenty of bottles which are donated by caring citizens or businesses.

The raw material for our artificial reefs is cheap and plentyful and with photos and videos of the results from our SGP/GEF project near the Tip of Borneo (Simpang Mengayu) and on Pom Pom island near Semporna, will lead to more community action projects around the region using the techniques we are developing to improve and rebuild the reefs close to each village. 

You may also want to read about our coral planting for world ocean day or Growth of the branching corals in the coral nursery.  or Step reefs or Bottle reefs or Shark cave reefs or igloo reefs

More blogs about TRACC marine conservation centre 

More info about learning to dive or volunteering to help save the ocean with TRACC in Malaysia - Turtle Snorkellers - Divers