coral reefs doomed for sure.

Bob Buddemeier buddrw at
Fri Sep 28 12:55:34 EDT 2001


Thanks very much -- you raise good points for discussion, and I think this is an
area where real (as opposed to definitional) debate can and should be
developed.  You obviously feel about bioturbation and bioerosion much as I do
about pore-water dynamics -- and clearly the two have to meet up somewhere at
the budgetary scale.  So, let's see if we can get there.

But first, to aid in the determining just what the topic/discussion thread is --
you addressed issues related to my point #3 (heavily) and #2 (somewhat).
However, if my point #1 is not in contention, then this is probably a new start
and not part of the "are reefs doomed" thread -- that point stated that due to
the solubility products/saturation indices of the various carbonate minerals, in
combination with the observed effects of reduced saturation state on coral-algal
calcification and the projected/modelled saturation state changes, the question
of whether or not high-Mg calcite buffered the surface ocean would be moot,
because any such buffering would be at a saturation state below that which would
produce the projected calcification effects over the next century.

So -- do you buy off on that?  Or does anyone else in the audience have
doubts/comments on that?  That's probably the first point to dispose of; if
that's not an issue we can move on to the sediment biogeochemstry questions as a
separate topic.

Bob Buddemeier

Mike Risk wrote:

> Bob, List-Some comments re the general discussion of changes in alkalinity,
> dooming of reefs, etc.
> Some of the following builds on previous postings on this list, and some
> amounts to a Discussion of the Kleypas et al 1999 Science paper. I was going
> to write a formal Reply to this, never got around to it...
> In general, my reservations about some of your positions are based on my
> belief that there has been insufficient consideration of two of the big
> Bio's in reef science: bioturbation and bioerosion. In addition, I have
> reservations about some of the chemical models/assumptions.
> 1. Bioerosion. The first quantitative work on the importance of bioerosion
> was published so long ago only me and Hendee were alive. Since then, there
> have been several large, exhaustive and exhausting studies of this signal
> process, and they have all come up with the same answer: on "normal" reefs,
> bioerosion and calcification are in approximate balance. On most fringing
> reefs, subject to increasing terrestrial nutrient input, therefore, the
> balance has already been shifted towards destructive processes. I will cite
> no references here. Knowledge of bioerosion should be an integral part of
> every reef scientist's knowledge base. In short, looking at corals is way
> less than half the picture: you should all know this.
> Unfortunately, this field seems to have fallen off the radar screen in the
> past few years: in the Amer. Zool. 1999 volume, for example, the word does
> not appear once. (Stop for a moment, and think of the gaping hole in our
> understanding that this reflects...) If it weren't for the French, there
> would be virtually no ongoing research on this process. (Salud, mes
> amies.) Any "reef monitoring" program that does not include
> assessment of bioerosion is a colossal waste of money-and I know of only one
> that does. Not only does this ignore most of the action-it excludes some
> prime bioindicators.
> Any "reef model" that does not include's hard to be polite, here.
> These models would better be termed "Less-than-half-of-the-reef models."
> 2. Bioturbation. Again, an exhaustive literature-lagoon and shelf sediments
> are vertically mixed on a timescale measured in months. Any number of
> critters involved here, of which the front-runners (in the Cenozoic) would
> be the thalassinid shrimp.
> 3. Oceanic/Climate Models. Notwithstanding their protestations to the
> contrary, I have found modellers to be resistant to data that upset their
> models, with that resistance being directly proportional to the amount of
> federal money invested to date. "One major problem with the current
> generation of GCM's is that the treatment of ocean circulation is still very
> crude." (Ruddiman, 2001: Earth's Climate).
> The implications of Smith et al, 1997, are that a meltwater pulse can divert
> or shut down the Gulf Stream in less than 5 years. To all of you out there:
> when the oceanic part of GCM's can model this, then start believing them-not
> before. The strong compartmentalisation of the mixed layer to which Bob
> refers is metastable, and temporary.
> 4. The Magnesium Salvation Theory-sort of reads like a cure for
> constipation, doesn't it? Stick to science, Mike.
> While I concur with some of what Bob says here, re porosity of reefs and
> reef sediments, I am not wholly persuaded:
>     -"...high magnesian calcites are dissolved preferentially in these
> sediments, although the sediment contains a mixture of (all types of
> carbonates). In deposits composed primarily of red algae, this early
> diagenetic reaction has resulted in dissolution of 75% of the carbonate."
> (Morse and Mackenzie, 1990: Geochem of sedimentary carbonates).
>     -"The data indicate that all samples are very close to equilibrium with
> Mg-calcite....alkalinity shifts relative to sea water indicate that initial
> precipitation may be followed by gradual dissolution in response to CO2
> added..." (Buddemeier and Oberdorfer, 1986).
>     -etc etc. And finally, Bob Halley and his USGS colleagues have done some
> very nice experimental work, some of which was reported in Bali, showing
> that, indeed, HMC dissolves.
> As far as the large inventory of HMC being buried-I think Callianassa and
> its cohorts have a great deal to say about that. Ain't going to happen. The
> sediments that reefs will produce in future, moreover, will likely be lower
> in relative concentration of HMC. The main contributors of HMC are the
> calcareous algae-CCA. As we eat the grazing fishes, and the urchins die off,
> and fleshy algae bloom in eutrophied coastal waters-reef seds will likely be
> higher in organics and lower in HMC.
> Some other points, perhaps more peripheral: high pH's have been recorded
> inside coral heads-indeed, pH's at which silicates are very unstable (Risk
> and Muller, Middle Holocene, Limnol. Oceanogr.-give me a break, I have only
> unpacked the first of 20 boxes of books). This will triggger dissolution of
> reactive silicates-in fact, the pH inside corals probably shifts 3-4 full
> units, making possible all sorts of neat chemistry. Don't forget, the
> sediments being delivered to the world's coastlines now are very different
> from pre-agricultural times. Now, we see reactive silicates-andesitic ash
> from 5-year-old falls, delivered to the coastline by rivers, may be seen
> hydrating and dissolving under 10-odd cm of carbonate sediments, at several
> locales in Indoensia. This is not a millenial timescale.
> So, in short, Kleypas et al:
> 1. depends on reef models that ignore >50% of the process
> 2. depends on outmoded oceanic circulation models
> 3. ignores some fundamental chemical questions.
> Other than that-we have to admit that it was an important paper, because it
> has stimulated a great deal of discussion. From that standpoint,
> congratulations to the authors. (Most of my papers disappear as neatly and
> as quickly-and as deeply- as Olympic springboard divers.)
> My main concern with that paper is that it may have diverted intellectual
> and financial resources from more pressing problems. Sure, changes in
> saturation state will eventually affect....what? What will be left, in say
> 100 years? pH changes in the ocean, in my opinion, don't make the Top Twenty
> Reef Threats. The rate of present destruction from land-based sources and
> overfishing simply dwarfs everything else.
> But we have three predictions running, now: I say (something like) "reefs,
> as some of us knew them, will be gone from most coastlines by 2020." Rupert
> Ormond says 50 years. Kleypas et al say a century. I hope to God they are
> right-but I don't think so. In fact, the reason I felt able to make that
> dire duo-decadal forecast is: it's already come true.
> I hesitate to enter the discussion about ABH-not because of ignorance (that
> has not worked in the past), but because Ove's doing a pretty good job
> stirring this pot. It seems to me that there might be some help, again, in
> the fossil record. One would assume that corals would adapt to rising
> temperatures (perhaps better than falling ones?). I am afraid, however, that
> my knowledge of the record isn't good enough, nor are the temperature data.
> Sea-surface temperatures are believed to have gone well above 30 in the
> Mid-Cretaceous, and mid-Cretaceous "reefs" (piles of rudists, really) are
> very low in corals...but this is far from conclusive. Perhaps one could look
> more closely at rudists, which had zooxanthellae, same as does
> Tridacna...corals, of course, have had zoox since the Paleozoic (Risk et al,
> Early Holocene, same excuse).
> The other problem with the record is the paleotemperatures. Planktonic
> forams give excellent results, for the open ocean. We really need shelf
> data-but many reports in the literature of paleotemperatures from benthic
> shelf critters are just not dependable. The problem is, the six people in
> the world who really understand KIE don't publish enough, and those that
> don't, publish too much. So this remains an open, and intriguing, question.
> On another note: I have to apologise to the List for exposing some of my
> personal affairs. That was forgivable only given my state of mind at the
> time. Nonetheless, several people whom I had never met sent condolences and
> best wishes! So-thank you, and it will never happen again.
> She has gone from
>     liquid food-IV drip, to
>     liquid food-juices, to
>     solid food-mushy stuff, to
>     liquid food-gin and tonics. So recovery is well under way.
> Mike
> ~~~~~~~
> For directions on subscribing and unsubscribing to coral-list or the
> digests, please visit, click on Popular on the
> menu bar, then click on Coral-List Listserver.

Dr. Robert W. Buddemeier
Kansas Geological Survey
University of Kansas
1930 Constant Avenue
Lawrence, KS 66047 USA
Ph (1) (785) 864-2112
Fax (1) (785) 864-5317
e-mail:  buddrw at

More information about the Coral-list-old mailing list