Coral nurseries and artificial reefs are a form of active restoration aimed at increasing coral health, diversity, or abundance. Corals are colonial organisms which reproduce primarily asexually to grow larger or repair damaged areas. Because of this feature, we are able to grow new coral colonies from smaller or broken pieces of coral, called fragments. Coral may naturally become broken due to many different threats such as large storms and waves, boat anchors, fishing nets, or irresponsible diving and snorkeling practices. These broken corals, when rolling around the sand, have almost no chance of survival, and usually die. But, by securing these fragments in good growing conditions they can be rehabilitated, nursed back to being a mature colony, and then transplanted back out onto the reef or onto artificial reef structures. In fact, it was Charles Darwin who first realized this about corals. He noticed that corals rolling around under the boat quickly turned white and died, but by securing the loose coral to a piece of bamboo pounded in the sand they would survive. For this he is credited with being the first coral restorationist. This is the basis of the coral nursery program initiated in 2007, with its first site placed in Ao Leuk Bay. The materials and methods have changed considerably since the time of Charles Darwin, but the ultimate goal is the same, secure dying corals before its too late.
Many nurseries have been created and a wide variety of techniques have been explored over the last 8 years since the coral reef restoration program was implemented on Koh Tao. Through time, they have learned what works well for the local ecosystem, and which methods receive the maximum yield with the lowest amount of material or labor costs.
In 2010, Thailand and the rest of the South China Sea experienced one of the worst coral bleaching events in the last decade. After this event, the Thai Government, along with local Universities, met to discuss ways in which the reefs could be remediated as well as protected in subsequent events.
Representatives from New Heaven attended several conferences and meetings in Bangkok, and pushed forward a plan to make local stakeholders more responsible for taking a proactive approach to reducing threats to reef health. Coral nurseries were identified at that meeting as one of the most accessible and efficient means of increasing reef resilience and helping corals rebound from bleaching.
The team then worked with the Save Koh Tao Group, the Thai Department of Marine and Coastal Resources, and the Prince of Songkla University to start and Adopt-A-Reef Program on the island. Other than New Heaven, 5 dive schools signed up to the program, and they worked together to increase the size and scope of coral nurseries. In 2010, the DMCR and PSU donated 48 coral nursery tables for the local dive schools to use and look after. Currently, New Heaven looks after the tables in Chalok Ban Kao and Ao Leuk, which is also home to our own coral nurseries.
In other areas, such as the Tanote Bay reef balls site, artificial reefs have been established between the DMCR and the local community. Every week, NH spend at least one or two days working on coral nurseries and artificial reefs around the island. It is important that they are maintained regularly, and there is always work to do there.
In order to get more people involved, including the local community, projects have been implemented that aim specifically at using coral nurseries to teach people about the threats to reefs and what can be done.
Most of the day-to-day artificial reef and coral nursery work goes on in Ao Leuk and Chalok, which are both very interesting sites that have been projected for about 4-5 years now. In Chalok we have the problem of repeated anchor dropping, so we construct structures to fill add substrate where the reef has been reduced to rubble.
In Ao Leuk they are trying to create a new reef, as an alternative dive site to reduce diving pressure on the natural reefs. Ao Leuk is the site of the first coral nurseries and artificial reefs constructed by the New Heaven Reef Conservation Program. The first structure here was implemented in December of 2008.
Originally the area was about 97% Sand, 2% rubble, and less than 1% living hard corals. The only animals commonly observed in the area where Shrimp and Gobies. Today the site is host to a wide range of resident fish and invertebrates including porcupine puffer fishes, scorpion fishes, rabbit fish, parrot fish, barracuda, trigger fish, pipe fish, and much more.
There are currently a wide range of different restoration techniques and methods employed at the site, including:
- Mid-water table and floating table coral nurseries
- Floating rope nurseries
- Fish nurseries
- Steel artificial reef structures
- Glass bottle coral/fish habitats
- Coral Larval Culturing Substrates
Recycled glass bottles set in concrete have been used to recreate a branching coral ecosystem in Chalok Ban Kao:
Photo credit to New Heaven Dive School