Beyond bioerosion.

Mike Risk riskmj at
Thu Oct 4 23:38:38 EDT 2001

I feel there is more that needs to be said on this, and other, issues. This
will, however, be my last submission on this particular topic.

Given the involvement of CO2, I am moved to consider the analogy of
scientific papers as automobiles. I view most of my papers as I view my
12-year-old Subaru, that sits mutely rusting outside: inconspicuous, easily
ignored, battered and beaten-but dependable transportation nonetheless.
Should someone volunteer to put some Bondo on it to fill in some of the
holes-well, be my guest. (You have Bondo? We need it up here.)

The responses of Kleypas and co-authors to my comments on Kleypas et al
(hereafter KEA, not to be confused with KIE) put me in mind of someone
waxing a brand-new BMW: putting further polish on that which is already near
perfection. Woe betide those who would point out dents in a fender, or nicks
in a windshield...I had hoped for a response something along the lines of:
"OK, we know there were some holes in the first version. We invite you all
to help us do better next time."-but that isn't going to happen here. The
difference between a discussion and an argument is: in an argument, no one
has any intention of changing their mind. This is an argument, one that has
gone on for over a month.

In that month, I estimate (using totally questionable assumptions!) that SE
Asia will have lost 2-3 coral species, and that coral cover on some of the
Florida Keys will have dropped another 2%. Reefs are in the midst of a mass
extinction event right now, and pH hasn't budged. (Yes, I know about the
open-ocean estimates-irrelevant, as you point out.) In the time I have spent
crafting these responses, I could have written a formal rebuttal of KEA, and
that is what I will now set out to do.

I also sense that the tone of the exchanges is becoming harsher, which is
upsetting. I realise I am to a large extent at fault, here, being a direct
and rude type. Those who know me may feel I have been well- behaved, whereas
those who don't may wonder why Jim Hendee let this raving maniac on in the
first place. So. After this one, I will give up. I have concluded that there
will be no substantive response to any of my comments.

I remain, as always, available for comments and exchanges, and would be
delighted to give of advice or information in any of the areas in which I
have some competence, as soon as I figure out what those areas may be.

To begin with: KEA have made their predictions, based on models they have
described in print and on the list. I am a field man (Omega, to me, always
meant expensive wristwatches), so I tend to look at field evidence. Just
about every reef worker (including Gattuso and Buddemeier) reports solution
of carbonate at night, when CO2 is elevated-and Halley's work shows that
this is solution of HMC. Additionally, KEA predict that corals should show a
6-11% decline in calcification since about 1880. Lough and Barnes (2000)
show an INCREASE in calcification of 4%, an increase that closely matched
the prediction of increased calcification from elevated SST's. So at least
one of their predictions is wrong already.

When I first saw KEA, I predicted that it would be used by managers to
divert resources away from local problems. This has already happened. In
addition, my doomsday scenario (Twenty and Out) is still running well, and I
will finish no worse than .500.

My rude comments about modellers (which really weren't mine, as I point
out-although I ascribe to them) were met by Dr. Kleypas with the following
series of responses (paraphrasing):
    -KEA really only used the HAMMOC model to illustrate the long time-scale
to buffering (although the model doesn't react quickly)
    -there are models out there now that CAN react quickly (but we haven't
used them)
    -and besides, there are all these famous oceanographers out there who
agree with us.
What can I possibly do, faced with this response, but retreat licking my
wounds? Seriously now, this is not convincing.

Dr. Kleypas attempts to bolster her defense of the ocean models by
denigrating/downplaying the importance of Smith et al, Nature 1997 (that's
OK, so do the modellers). While she claims "corals from a single not provide adequate evidence" , that same finding was
trumpeted, by one of her own quoted oceanographers, as "The New Archive that
we've all been waiting for." Would you have asked Newton to wait for MORE
apples??? Sure, it's only one location-but it's the most precisely
constrained major climatic event ever to be described from the ocean record.
The results won't go away. The implications are that the Gulf Stream Return
Flow disappeared/deviated/whatever in 5 years. This implies a fundamental
mixing of the oceans during major climate changes, mixing which will screw
up the rest of the predictions in KEA. (I treat these postings as my
lectures-I only repeat myself if I feel the audience wasn't listening.)

Note: for those of you interested in paleoclimatology: Smith et al 1997, and
the companion piece, Smith et al, 2000 (PALAIOS), provide an isotopic
Rosetta Stone, a solution to the annoying effects of KIE (this is a process
which makes many coral isotopic climate records simply undependable).
Precise water temperatures, any ocean, any coral, any depth. The "lines"
paper, in PALAIOS, took corals from all over the world, used thousands of
isotopic measurements to show that the slopes of lines in O-C space,
independent of KIE, were a thermometer.

After Dr. Kleypas' response, I went back, and I searched through that Am.
Zool. volume, and By God I found it! In Kleypas et al, on p. 153, we see
(refs removed to save typing) "...nutrient excess probably limits reefs
indirectly by enhancing macroalgal competition for space, phtoplankton
competition for light, and bioerosion." And that's all. Instead of claiming
to have "mentioned bioerosion several times as an important control on reef
development," I think she should have 'fessed up, said "OK, we left it out,
we'll do better next time. Can you help us?" Ain't going to happen. (By the
way, the Gattuso et al paper in that same volume is one of the nicest
summaries of coral gas and nutrient metabolism I have read.)

I'd like to go over some of this again. I do apologise in advance for some
of the self-citations: there has already been too much of this in these
exchanges. I do so only when  one of my rusty old beaters was the only one
on the lot at the time...

The classic studies on reef budgets were done in the early 70's, based on
field work done (in some cases) commenced in the 60's. The results have
never been challenged: bioerosion equals calcification, with large errors.
(Where calcification spikes up, we get reefs-where it does not...sediment.)
There have been a few studies directly relating bioerosion rates to nutrient
concentrations. Rose and Risk (1985-Mar Ecol 6: 345-363) found that density
of Cliona delitrix increased in lockstep with the abundance in the water
column of fecal bacteria. (No phosphates, no nitrates-plain old poop. Turtle

Since the early 70's, when those papers were done, coastal nutrient
concentrations/eutrophication levels have AT LEAST doubled. In other words,
bioerosion is now FAR MORE IMPORTANT than the corals! The treatment of this
subject in the Amer Zool volume simply exposes the huge lacuna in the
skill-set of today's reef biologists.

So reef monitoring programs that omit bioerosion are a joke, as are reef
growth models. It is to be hoped that rapid readjustments are under way as
we speak.

But let us examine the role of bioerosion in calcification
budgets/alkalinity reduction studies.

Microborers have been around since the PreCambrian, and comprise several
phyla: blue-green algae (yeah, I know, Cyanobacteria-but geologists still
call them blue-greens), greens, reds, fungi...They are in every grain of
sediment, every coral, every shell, every coral that has ever been stuck
into a metabolic chamber...most of the destruction is done by the green
algae, via secretion of short-chain organic acids, such as formic, oxalic
(good for taking rust off cars), malic. As usual, the stoichiometry eludes
me, but here is what I see:
    -because they manufacture short organic acids thru photosynthesis, the
CO2 balance may be close to a push (one in, couple out).
    -their eroding activities, however, crank up alkalinity values, via a
process that appears in the gas-exchange models as PS. In other words, the
O2 production of the corals, which is calcification, is mixed with the O2
production by alkalinity-pushers.

That's just the greens. There is evidence that the blue-greens may be
heterotrophic-like graduate students, there's no telling WHAT they do at
night...the fungi are saprobic, dikaryomycotan anamorphs-common terrestrial
fungi. You have some in your fridge now, on the bottom shelf, at the back
there. (Kendrick et al. 1982, Bull Mar Sci 32: 862). They invaded via
beachrock or.....African dust!

I had hoped that Bellamy and Risk (1982: Science 215: 1618-1619) would have
been more widely absorbed by calcification modellers: we found very large
amounts of oxygen, produced by boring algae, stored in the tips of Millepora
on the GBR. If you "ping off" a tip, not only will you see clouds of
bubbles, you may even hear the hiss of escaping gas. (No, please don't do
it!) Shasher and colleagues, in Israel, in a series of elegant experiments
on "life in extreme environments", estimated that the amount of respiration,
the metabolism, of boring algae lying directly under live coral tissue was
small-so perhaps they may safely be ignored? No.

On the contrary: the ones in corals are light-limited. In sediments and
hardgrounds, they have a major impact. Tudhope and Risk (1985: J.
Sedimentary Petrology 55: 440-447) estimated that boring algae dissolved
between 18 and 30% of the TOTAL sediment input into GBR lagoons. These were
extremely conservative estimates, and the real value is undoubtedly higher.
In that paper, there is a section on the relevance of the results to
whole-reef calcification estimates using alkalinity reduction techniques. P.
446: "...loss of carbonate from the reef system due to dissolution of
sediments by microborers is a more important factor in whole-reef budgets
than previously recognised"-and it remains unrecognised.

I would invite KEA to explain to me, and the list, how the influence of
microborers on gas exchange over reefs has been handled in their models.

Finally, I am deeply distressed that my anguish at the demise of the
ecosystem in which I have spent most of my life should be dismissed as pique
at "my own reef issue being overshadowed" by the predictions in KEA.
Firstly, I don't think their predictions are worth much-but far more
importantly: I am as far as I know the only reef scientist who has had the
courage to speak out in print against the factionalism that paralyses reef
science (Risk 1999, Mar. FW Res 50: 831-837). It is unacceptable to me that
I be accused of the same turf-war mentality. It is unacceptable, and I am
very angry about it.

Message ends-thank you all for your  indulgence.

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