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Specialist Forums > Conservation Forum > Bubble trouble
posted : September 9, 2004 Post subject: Bubble trouble
bet as divers you are all aware that it is inadvisable to touch corals on reefs. I also bet that most of you know this is because you may damage the corals in doing so.
We are all told, during some part of our diver training, that coral reefs are a delicate and complex ecosystem (much like a tropical rainforest) provide habitat for thousands of different species of corals, fish and other marine life. Not only do they provide a home for theses creatures, but in doing so, they attract sharks and turtles, rays and octopus and other cool things to look at!

What we may not be told during our diver training is that as divers, we pose one of the most important threats to coral reef well-being.

For my undergraduate degree, I carried out research into the causes and effects of coral reef damage with a specific interest in diver damage. It was found that amongst the many man-mad threats to coral reefs, divers may cause significant damage if they are not aware of their underwater surroundings. The main findings of my work were that divers my have three types of contact with a coral reef - Accidental contact, Incidental contact and Indirect contact. Incidental contacts are contacts made 'on purpose' i.e. to prevent from banging into the reef or holding on when taking a photo. These types of contacts are the least damaging, as long as the diver is not touching live coral and they are not under an overhang. If the diver is under an overhang (or at the entrance to a cave)the exhaled air bubbles may cause significant damage to the coral reef in two ways:
1 - Corals cannot survive for prolonged periods in air. Therefore if trapped air forms pockets, any coral in that pocket will be killed.
2 - The physical force of rising, expanding air will pass through delicate branching corals such as acropora (staghorn coral)or sea fans and may break or damage the coral. The area under an overhang is of massive ecological value as it acts as a nursery from juvenile fish. Without these habitats, fish populations may come under threat.
This type of contact, from bubbles, is an indirect contact.

Other indirect contacts such as wash from fins or hands may also damage the coral. The wash of your fins kicks up settled sediment which then re-settles on the coral polyps and effectively 'suffocates' the coral. Corals do have mechanisms to counteract this but increased levels of sediment can adversely affect the corals health. In some cases, fin wash may not be so significant as strong currents can have the same effect on sediment.
The final contact type is the accidental contact. Along with bubble contacts, this is the most destructive. These occur when a fin kicks the coral, a cylinder hits the coral or a body or hand bumps into the coral. These types of contact are common in trainee and newly qualified divers that often have not perfected their buoyancy control and also amongst photographers, who may be desperate to get a good photo but don't notice the coral they are kicking the life out of!

Some measures are being taken to try to reduce the numbers of diver contacts with the coral reefs of the world. For example the PADI Project AWARE video is very good but does not mention bubble damage. Other schemes, such as the one run by the Hurghada Environmental Protection Agency (HEPCA) in the Red Sea aim to educate people about diver impacts, but more must be done.

I questioned dive tourists in Indonesia, one of the most pristine dive areas in the world to see what they wanted from coral conservation and 100% of respondents wanted their future children to be able to experience the reefs they had experienced. I am sure that you want the same from your children in years to come.

If you would like any further information about my research, please feel free to email me.

Jamie Walker
The University of Birmingham
B15 2TT
United Kingdom

posted : December 26, 2004 Post subject: Bubble trouble
Hello Jamie

I would be interested in reading your research as a keen diver in Australia for personal interest.

I also attended UOB - Chem Eng.


posted : March 29, 2005 Post subject: Bubble trouble
very interesting reading. I the naturalist division of a marine conservation organisation within the rereational diving industry in Honduas and would be extremely interested to read your work and pass the information on to the 10,000 or so divers that come to this island each year.
Please email me

Bert van der Togt
posted : June 19, 2006 Post subject: Bubble trouble
Hello Jamie,

My name is Bert van der Togt. I am currently active as a volunteer national park ranger in Dahab, Red Sea, Gulf of Aquaba. One of our projects is to assess diver related coral damage and take appropriate actions to preserve the reefs. One of our divesites has a cave like structure known as the fishbowl. Divers have been passing through this structure for years and it is definately deteriorating. I am currently doing a literature study as part of a project to close this passage to divers in order to preserve it. I am therefore very much interested in your work and would like to read it. Thank you in advance, I hope to hear from you soon.

Kind Regards,
Bert van der Togt (

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