[Coral-List] causes of Acropora loss

Michael Risk riskmj at univmail.cis.mcmaster.ca
Wed Oct 3 10:32:08 EDT 2007

Good day, all.

John's posting suggests that I should have amplified some of my rather
cryptic comments. This is particularly pointed (poignant?), coming on
the heels of Bill Precht's justified expressions of outrage at his fine
research being so mis-used, and Martin Moe's posting about mass deaths
of sponges. Martin and I are really saying the same thing... 

First of all, "global warming" vs. "global change." I confess this was
deliberate, and as Gene will tell you some of my little jokes are a tad

"Global change" was the term adopted by the US gov't. as the more
palatable alternative to "global warming." After all, who could
possibly oppose change? So this term evokes two responses, which may be
mutually incompatible. It may remind us of the manipulation of science
by politicians with agendas. It may also mean just what it says-and,
because that may encompass geologic, astronomic and anthropogenic
change in any number of systems, the term quickly becomes virtually

Secondly, decline. Space does not permit a thorough discussion of this
topic, so I will be cruelly brief. I believe the Acropora dieoff is a
microcosm of the Caribbean (and global) reef decline. This is a process
that has been under way for almost a century. For discussion purposes,
let us assume that the graph in Gardner et al 2003 represents the
trend. I am prepared to accept this graph, because it supports the
reports and opinions of every senior reef scientist I know. The work of
people like Walt Jaap, Gene Shinn, Phil Dustan, Walter Halas, Jim
Porter and, yes, Tom Goreau should have alerted us to the disaster long
before Gardner's paper came out. (Coral reef science doesn't eat its
young, it ignores its seniors.)

I am not an expert on disease, but in the recent NOAA-sponsored coral
disease workshop in Hawaii, we decided that, of the 7-odd types of
coral disease already identified, at least 6 had a linkage to the land.
The discovery in Jim Porter's lab that White Pox is a fecal bacterium
just backs this up. The recent paper by Maggie Nugues and Rolf Bak (Hi,
guys) suggests also that some diseases have been around a very long
time, and only emerge when corals are stressed.

When John asks for papers linking Acropora diseases to land-based
sources, I read that as exposing a lack of good science. This is
something I have commented on before, in Paradise Lost, but it needs
re-stating. There is a ton of work on predicted alkalinity changes in
the oceans, and a mountain of work on bleaching-but take a close look
at the Gardner trend. By the time of the first widespread bleaching in
Florida, the Caribbean was down to maybe 30% of its original richness.
There is a strange lack of research on mundane items like sewage
impacts, sediment stress, etc.

(I wish to be clear here: I have no doubt that human-induced global
warming is the major threat facing us all now, and that it will in time
slay every coral in the surface oceans. But this will be after
land-based sources had already killed 95% of them.)

If we take a quick look at Coral Reefs, over the past year or so it has
published more than a half-dozen papers on bleaching and acid
oceans-and only one, a Reef Site one-pager, on land-based stresses, by
Brian Lapointe and co-authors. (It is time for the reef research
community to admit that Brian has been right all along.)

I keep insisting to my wife that I'm not a cynic, I'm a realist. I
think one of the reasons for the gap in the research, and in the
acrimony that characterises some exchanges among reef scientists, is
simple: show me the money.

I recently testified at a town meeting in Lake Worth, Florida.
(Financial disclosure: I did it for free.) Lake Worth wanted to dump
nutrient-enriched RO water onto one of the few remaining reefs in
Florida. It was me against 6 highly-paid Suits, three of whom were
faculty members at Florida universities, and ALL of whom thought this
was just a fine idea. 

So when John says he wants to see the research, I see a research gap,
and I don't think that gap is accidental. I find this very sad. My
grandchildren (two so far, one on the way, thank you) will never see
the reefs I have seen, and one of the reasons for this is: scientists
in their 20's and 30's now working in the Caribbean have never seen a
real reef, and have no idea what has been lost.


On Tue, 2 Oct 2007 15:26:18 -0400
 John Bruno <jbruno at unc.edu> wrote:
> Mike Risk wrote:
> > Acropora is threatened by a host of things-and there is ample
> > evidence to this effect-but not (so far) by global warming.
> >
> > The Caribbean-wide decline of reefs has nothing to do with global
> > change, and a lot to do with things like land-based sources,
> > overfishing, etc. It is easier to arm-wave about CO2 than it is to
> > advocate controlling development.
> Three quick points;
> First, Mike is (probably accidentally) conflating global warming and
> global change.  Global change includes warming but also many other  
> changes like increased sediment and nutrients, novel diseases and  
> disease outbreaks, etc.  (wasn't there a discussion about this just a
> few weeks ago?).
> Second, I am unaware of any evidence supporting Mike's contention  
> that the Caribbean-wide loss of Acropora in the 1980s was caused by  
> land-based sources (assuming he means nutrients) or by fishing.  If I
> am missing some published work in support of this hypothesis, I'd  
> really like to hear about it.  I have long been convinced, based on  
> my reading of the literature and the patterns I have observed, that  
> the loss of Acropora was caused overwhelmingly by the white band  
> epidemic, which as far as we know was not related to any human  
> alterations to the environment.  If humans are to blame, I'd bet it  
> would have something to do with introducing a novel pathogen.
> Third, I have heard from several colleagues about recent bleaching- 
> related mortality of Acropora cervicornis over the last few years.   
> Ernesto Weil has noted frequent mass-Acropora bleaching in Puerto  
> Rico that nearly eliminates cervicornis every time it begins to  
> recover.   Thus I think temperature and possibly climate change could
> be playing some role in retarding the Acropora recovery, even if it  
> was not the principle cause of the decline.  Is anyone aware of  
> recent studies of Caribbean bleaching and subsequent mortality of  
> Acropora species that would support this?
> Ciao,
> JB
> John Bruno, Ph.D.
> Associate Professor
> Department of Marine Science
> The University of North Carolina at Chapel Hill
> Chapel Hill, NC 27599-330
> jbruno at unc.edu
> www.brunolab.net
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Mike Risk
Marine Ecologist
PO Box 1195
Durham Ontario
N0G 1R0

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