The development and construction of artificial reefs has increased steadily over the last few years. Upwards of 25% of coral reefs worldwide have been destroyed over the last 20 years and the remaining reefs are threatened by a multitude of factors including; unsustainable fishing practices, pollution, tourism and the effects of climate change on ocean temperatures and acidification. The world’s coral reefs have taken on an important part of global marine preservation.
What Are They?
Artificial Reefs are human made underwater structures, which are mostly built to provide marine life an area in which to live and thrive. Usually the reefs are placed in areas with a generally featureless bottom with lots of sand. Any solid object can be placed down to create a new reef as long as it is not harming the environment.
Locally, here on Koh Tao we have sunken toilets, domes, animal structures and pyramids as parts of our artificial reef structures, all of which provide a good substrate for coral to settle on and in time provide a nursery for marine life.
Artificial Reef Goals
The main aims of creating an artificial reef are….
- Provide and alternative dive site for divers
- To increase the coral reef /marine population in the local
- Scientific research
- An attraction for scuba divers
- Provide an area for rehabilitation when damaged by human / natural causes
- Create an artificial reproduction zone
The History of Artificial Reefs
The construction of artificial structures can be traced back many thousands of years to ancient Persians blocking the mouth of the river Tigris to prevent enemy ships from entering ports for raids. The Japanese have been building structures to attract fish for many hundreds of years.
They are determined to ensure they do not run out of sushi..!!
For the past thirty years’ countries such as USA, Canada, Australia and more recently Thailand have been placing various objects underwater, such as decommissioned naval vessels in order to attract scuba divers.
Generally, the objects placed underwater, whether self-built, or in the case of sunken naval boats already constructed, provide a hard surface which over time will be colonized by underwater marine and plant life.
To help populate developing reefs we gather small broken pieces of coral which may have been broken due to irresponsible or poor scuba diving techniques, boat or anchor damage or perhaps storm damage. These pieces would normally roll and around in the sand and die.
By securing these fragments using different techniques, they stand a much better chance of surviving, creating a suitable home for marine life and with time an alternative site for divers to enjoy.
When constructing an artificial reef aimed at generating coral you can assist in the structural development by applying a low voltage current. Commonly known as Biorock, the process involves applying a low voltage current through a metal based structure which encourages limestone to form to which Coral Planulae attaches itself.
Once attached the current then speeds up the growth of the coral at a faster rate than it would naturally form.
Koh Tao’s Artificial Reefs
Artificial reefs have been a feature of Koh Tao’s underwater environment for just over a decade in which time we have seen the number steadily increase. Hin Fai, Buoyancy World, Junkyard Reef, HTMS Sattakut, Aow Mao and MV Trident offer some great dive sites and important structures to preserve the marine habitats around our island.
Located just off the north west coast of Koh Tao facing Koh Nang Yuan, the Save Koh Tao group implemented our very own artificial reef using electrolysis to encourage coral growth, named ‘Hin Fai’ (which translates to ‘electric rock’ from Thai). We have seen great development in the corals which in turn have increased the bio diversity of the site itself.
Another Biorock has also been recently deployed at Aow Leuk.
The HTMS Sattakut is an old Navy ship which was donated to Koh Tao by the Thai Navy for use in creating a site which would provide a training site for the Wreck speciality course and also encourage a new area in which marine life could thrive.
This has quickly become one of the most popular dive sites for Advanced Open Water divers due to the deep depth with the site attracting a variety of marine life.
This site was originally created by Crystal Dive and Eco Koh Tao in 2009.Lying 400 metres off the Mae Haad beach in what was a shallow barren part of sand. Years later and with much work from Crystal Dive’s dedicated in house conservation and environmental team, Junkyard is now a thriving reef.
Named Junkyard Reef because the original objects were basically just junk lying around close to Crystal Dive itself, the toilets, car and tables have become home to many different species of fish. This area has also become an important coral nursery with many structures being placed down with the purpose to hold nurseries.
In 2010 the Thai Department of Marine and Coastal Resources (DMRC), in conjunction with the Prince of Songkla University started an ‘Adopt a Reef’ program here on Koh Tao. The objective was to increase the size and scope of Coral Nurseries around the island and they donated 48 Coral Nursery Tables to which Crystal Dive and Eco Koh Tao maintain tables at both Twin Peaks and Junkyard (Pictured)
An Island wide project which has seen most dive centres on the island come together to create a new site just to the North of the Twins dive site. The idea was to create an area to improve bio diversity and also a training site for student divers to help improve their buoyancy with the added benefit of reducing damage to the natural reef to the South.
A hugely popular site for beginner divers Buoyancy World features concrete structures such as a shark, octopus, lizard, the Crystal Wreck, Mangrove Forest, Sea Urchins and many others.
Blocks donated by the DMCR to create an artificial are just one of the many artificial reefs that have been deployed. These prove a hiding place for fish, new substrate for coral to settle on and a perfect place for people to practice their buoyancy skill.
Author: Jenny Dowling (Eco Koh Tao)