[Coral-List] Carbonate balance.

Michael Risk riskmj at univmail.cis.McMaster.CA
Thu Oct 19 14:43:35 EDT 2006

Hello John.

I am sure by now the list is getting heartily sick of me. Nonetheless,
your query was directed to all, plus me, so I will try to answer you

The body of research involved here is so extensive my fingers ache at
the thought of typing out even a fraction of them. (Should you want
some of the key refs, please contact me directly so we won't burden the

There have been several studies of carbonate budgets, all giving the
same answer (the one I reported). The best of them, and one of the
earliest, was the huge Edinburgh/McGill-Scoffin/Stearn study of the
Bellairs reef off Barbados (which is no longer there). This involved
armies of students and shelves of theses. A couple of refs here would

Scoffin, T.P., Stearn, C.W., Boucher, D., Frydl, P., Hawkins, C.M.,
Hunter, I.G., MacGeachy, J.K., 1980. Calcium carbonate budget
of a fringing reef on the west coast of Barbados. Bulletin of Marine
Science 30 (2), 475?508.

Stearn, C.W., Scoffin, T.P., 1977. Carbonate budget of a fringing reef,
Barbados. Proceedings of the 3rd International Coral Reef
Symposium 2, 471?476.

True, there are two ways of removing material. Sponges dissolve only a
fraction of the carbonate (about 5%), and the rest is removed as
silt-sized material. Then the beat goes on: sipuncs are mechanical
(mud-size material), as are some worms-but most worms are chemical.
Bivalves are chemical. etc. And this is INTERNAL only.

Probably the second-most important bioeroding group is the algae. This
is purely chemical dissolution, via metabolic byproducts, and is so
rapid that, in shallow water, the "half-life" of a carbonate sand is
<20 years. As you watch it, it gets smaller...

The vast majority of sediment produced internally in a reef which grows
at or above wavebase is removed from the reef, and unavailable for
catch-up, give-up or keep-up. But maybe for surf's-up, because it goes
to make beaches...

Hope this answers some of your questions.


On Thu, 19 Oct 2006 13:08:32 -0400
 John Ware <jware at erols.com> wrote:
> Hi Mike (and List):
> While I usually find it wise to practice "Risk avoidance", I can't
> help but revisit the statement that you made which is quoted below:  
> >-bioerosion accounts for >50% of the carbonate balance of a reef,
> and
> >  
> >
> I realize that I am just an engineer who got into coral reef stuff
> rather late in life and I find myself often confused by various
> terminology.
> When someone uses the phrase "carbonate budget" I think of adding up
> all the things that make calcium (and, I suppose, magnesium)
> carbonate and deposit the result on the reef.  The negative things
> are the things that result in CaCO3 being removed from the reef.  
> Now it seems to me that there are two ways to remove CaCO3 from the
> reef: 1- pick it up and take it somewhere else; 2- dissolve it back
> into the ions from which it has come.
> I may be wrong, but I thought that the vast majority of bioeroders
> (as the term is commonly used) spend there time "making little ones
> out of big ones", not actually dissolving the CaCO3.  I seem to
> recall from something I read somewhere that Cliona does both.
> If I am indeed correct that the majority of bioerosion simply results
> in smaller particles, then their removal from the reef has nothing to
> do with the bioerosion itself.  Water motion and gravity do the
> removal.
> One more comment is that, from what I have read, making little ones
> out of big ones is essential to reefs keeping up when water level is
> rising. The old, catch up, keep up, or give up.  Corals don't look
> like trees, 
> they don't keep up with rising water level by growing taller.  A
> substrate has to be made for growth of new corals that is higher than
> the previous substrate and corals won't do this by themselves.
>  Grinding the corals into fine particles, the particles being
> cemented together, and so forth is what allows keeping up.
> John
>     *************************************************************
>     *                                                           *
>     *                      John R. Ware, PhD                    *
>     *                         President                         *
>     *                      SeaServices, Inc.                    *
>     *                   19572 Club House Road                   *
>     *             Montgomery Village, MD, 20886, USA            *
>     *                       301 987-8507                        *
>     *                      jware at erols.com                      *
>     *                 http://www.seaservices.org                *
>     *                     fax: 301 987-8531                     *
>     *             Treasurer and Member of the Council:          *
>     *            International Society for Reef Studies         *
>     *                                          _                *
>     *                                         |                 *
>     *   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~ *
>     *                                        _|_                *
>     *                                       | _ |               *
>     *        _______________________________|   |________       *
>     *     |\/__       Untainted by Technology            \      *
>     *     |/\____________________________________________/      *
>     *************************************************************

Mike Risk
Marine Ecologist
PO Box 1195
Durham Ontario
N0G 1R0

More information about the Coral-List mailing list