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Thread: The effect of bubbles on reef health...or lack there of

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    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Copis Meg and rEvo III

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    The effect of bubbles on reef health...or lack there of

    I’m doing research on a vacation to Roatan...actually leaning toward Cayos Cochinos, a smaller archapellago MPA, because i have been reading about how beet up the reefs of roatan have gotten, in particular, mary's place, a dive site of swim throughs and narrow channels.
    I've been wall diving in Fiji, the red sea, coz, the pacific north west, CA, Baja and have oftened wondered about the effect that the water turbulence/lift from OC scuba bubbles have on reef health. Walls that get dove a lot tend to dye back. It might sound silly but I just put two and two together and realized that one other likely benefit of rebreathers is their low impact on reefs. it's no secret that the worlds reefs are dying the world over... while there are many sources of pressure on reef ecosystems, could diving closed circuit reduce the impact that divers have? are the effects of OC on reef health significant enough to warrant large scale change.
    I've been diving and had debris...ie. critters drop down from above where my bubbles were making their way up a wall. Pockets of air collect under over hangs and under outcroppings…most certainly causing dead spots. While puritanical environmentalism gets old fast, I do wonder what the cumulative effect of OC is and what the benefits of leaving some places rebreather only might be. Does anyone have opinions or research about the effects of OC bubbles on reef health and conversely the low impact of rebreather diving on reefs.

    Gill Envy

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    RBW Member JimG is on a distinguished road JimG is on a distinguished road JimG's Avatar
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    Re: The effect of bubbles on reef health...or lack there of

    Speaking as a biologist, I think bubbles are a minimal problem. Reef damage is mostly due to development (e.g. sewage) and physical damage from fishing, shipping and other activities. Clearly, areas with lots of scuba diving can be damaged physically by divers--mostly due to poor buoyancy. I would find it hard to believe that bubbles cause any significant damage.

    In an analogous situation, last week I went into a moderately popular cave system in North Florida (Hole in the Wall). Like most often-dived Florida caves, the walls seemed rather smooth and rounded with only blunt projections. We were on rebreathers and went further than most OC divers can get (we did 3.5 hr total dive time). When we passed about 2000 feet penetration on our way to 3000 feet, the cave changed completely. There were many fragile and sharp-appearing projections and features, and I realized that in the areas nearer the entrance these had all been broken off and ground down by divers over the years, something you see in the systems with high numbers of divers like Ginnie Springs and Peacock Springs. I've often wondered about bubbles that collect in pools along the ceiling until they finally work through the rock, but abrasion by divers is the most obvious damage.

    I think the same thing happens in reefs, but for places around a lot of human development such as the Florida Keys and the Carribean, the main problem is unrelated to diving.

    I've been to popular dive sites near Cairns Australia in the barrier reef, where corals are clearly damaged by divers, compared to pristine sites where I do research within Papua New Guinea, but again- I think its mostly physical abrasion from poor buoyancy and carelessness, not the bubbles.

    Its not that I think bubbles have no influence, but I think as far as diver impact goes, its mostly just that -- diver impact!

    JimG
    Tampa

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    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Copis Meg and rEvo III

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    Re: The effect of bubbles on reef health...or lack there of

    Just a little article i found on the subject at:
    www.ukdiving.co.uk/forums/topic.php?t_id=199

    an excerpt:
    " 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. "
    by
    Jamie Walker
    SGEES
    The University of Birmingham
    B15 2TT
    United Kingdom


    i went do coz a few years back and dove devel's throat a cave that went from 80 ft down into a sea mount and dropped you out on a wall at 140. I thought it was pretty cool but one of the folks on the trip had done the dive 10 years earlier and was really dismaid at the lack of crowth inside the cave compared to the first time they had gone through it...likely a combonation of bubbles, tanks and fin damage. I'm still curious to see if rebreathers are less impacting in such places.

    Gill Envy

  4. #4
    RBW Member spottydog is on a distinguished road spottydog is on a distinguished road spottydog's Avatar
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    Re: The effect of bubbles on reef health...or lack there of

    Hi from OZ.

    As a guy who has kept a reef in a tank, I think that the "bubble dammage" if it exists is relatively minor. (gut reaction, as the exposure to the air is relatively short, and most corals will survive a few hours air exposure).

    The physical action is somewhat different.

    Acropora is pretty tough physically, It's quite hard to break the smaller tips of branches without using tools for instance.

    If a tip of a branch over 1 inch long is broken off and attached to a piece of rockwork (with super glue or epoxy resin) it will grow happily around 50% of the time, in a smallish tank with imperfect water conditions, but with good lighting.

    With poor lighting the "frag" has little chance.

    It is quite common in the hobby to prune larger acroporas heavily as they start to overshadow the rest of the tanks coral, to its detriment.
    The pruning to the parent is a small risk typically.

    This indicates that in the much better water conditions in the wild there is little real difference if the odd piece of coral gets hit and "fragged".

    The real problem we have in captivity and it is sugested (highly probable) in the wild is the modification in the environment caused by our presence.

    Often the hobbyist feeds the fish and invertebrates more than is required, (fat looking fish are nice) without some suitable mechanism to remove the waste products, leaving an excess of Nitrates and Phosphates in the water.

    This always creates an increase in the ammount of algae in the tank, which out competes the corals the hobbyist is trying to keep. You end up with a green looking tank, which doesn't represent the reef environment the fish are from.

    I suspect that the byproduct of our presence on a reef, or onshore nearby is the equivalent to this nutrient enrichment of the captive reef.

    Ie. Hurghada and Sharm in the red sea, theres been a massive recent growth in the numbers of visitors. Many grassed areas with irrigated soil. This looks like an excellent example of a way to increase the nutrient levels of the surrounding fringe reefs. (aside from the other potential sources, grubbing up mangroves, a natural nutrient trap, and any waste water that ends up in the sea).

    I've also seen an increase in the volumes of coral that thrives in relatively nutrient rich water near sharm. much less in hurghada. (HEPCA do a fine job, but I don't think they're actions have resulted in this difference).

    In the end, I don't think our physical presence diving on a reef is as serious a problem, in comparison to the almost inevitable polution we create as a byproduct of our presence.

    One really positive thing is that we are there to see the differences as they happen, and this engenders a huge concern for the general reef environment, resulting in action aimed at sustaining and protecting it.

    -Al.
    Last edited by spottydog; 21st January 2006 at 13:41.

  5. #5
    New Member Royal Red is an unknown quantity at this point Royal Red's Avatar
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    Re: The effect of bubbles on reef health...or lack there of

    Not sure about bubbles causing reef damage but do know that the use of a closed-circuit rebreather will significantly reduce bubbles and also significantly reduce the fear of sharks to approach a cc diver.

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