The destruction of the world’s coral reefs has been in the news for quite a few years. A large focus is on the Great Barrier Reef, but in fact 30 % of all reefs are critically damaged and this is expected to increase to 60 % of reefs by 20301.
What is the reason the reefs are being destroyed then? There is no simple answer, since the reefs are impacted by numerous events and processes. These include:
- Pollution – more nutrients lead to algal blooms, which can prevent sunlight from reaching the corals and hindering photosynthesis.
- Overfishing – leading to a loss of the fish that eat algae causing the same problems as pollution.
- Ocean Acidification – the acids in the water dissolve the calcium carbonate skeletons of the corals.
- Natural disasters (hurricanes and storms) – causing physical damage to the corals2.
- Bleaching – a phenomenon not only related to the sun, but to disturbances in the water (e.g. increase in water temperature or a decrease in sunlight) killing the zooxanthellae (brown algae symbionts) in the coral leaving it transparent.
This may seem grim, but all is not lost! Coral reefs can be restored through a few different measures:
- Letting the reef recover naturally – corals are resilient organisms that can repair themselves given enough time3.
- Transplantation – corals from a healthy reef are moved to a damaged one.
- Coral nurseries – coral fragments are grown in a protected area and used to restore damaged reefs through transplantation4 (see above).
- Artificial reefs – structures are submerged to improve the health of the reef by e.g. providing a suitable surface to grow on (see picture). These have had varied success.
- Modern Technology – using new techniques that mainly focus on aiding the coral larvae in settling. These techniques include running an electric current over a surface to encourage settling and investigating the internal biology of the corals whereas mainly the external biology has been considered previously5.
If you are interested in finding out more about these measures and a few additional ones, I highly recommend checking out the paper by Baruch Rinkevich in 20055.
You may ask yourself: “Why should we save the coral reefs?” That is a good question and one that often gets lost in all kinds of conservation, probably because it’s such an obvious thing to the conservationists.
Coral reefs house a plethora of animals, from colourful fish to microscopic plankton. Without the reef, these animals have nowhere else to go and would quickly disappear due to a lack of food and an increased likelihood of being eaten since they can’t hide anywhere. Many reefs are also important economically; young fish spend time in the reefs before moving on to the open sea where fishermen can catch them and the Great Barrier Reef
generates more than 1.5 billion dollars for the Australian economy through tourism and fishing (check this link to find out more).
- Hughes, T.P. et al., (2003). Climate Change, Human Impacts, and the Resilience of Coral Reefs. Science 301: 929-933
- Hurricanes, B. T. (2008). 3. Hurricanes and their effects on coral reefs. Status of Caribbean coral reefs after bleaching and hurricanes in 2005, 31.
- Ammar, M.S.A. (2009). Coral Reef Restoration and Artificial Reef Management, Future and Economic. The Open Environmental Engineering Journal 2: 37-49
- Shafir, S., Rijn, J.V. and Rinkevich, B. (2006). Steps in the construction of underwater coral nursery, an essential component in reef restoration acts. Marine Biology 149: 679-687
- Rinkevich, B. (2005). Conservation of Coral Reefs through Active Restoration Measures: Recent Approaches and Last Decade Progress. Environmental Science and Technology 39: 4333-4342