[Coral-List] Diademia Coral-List Server

Martin Moe martin_moe at yahoo.com
Fri Oct 6 10:23:10 EDT 2006

Hi James,

You make some very good points in your post. I am, of
course, not unaware of the great stresses we have
placed on our reefs from anthropogenic release of
nitrogen and phosphorus, addition of a great variety
of organic and inorganic pollutants, global warming,
microorganisms and nutrients from sewerage discharge,
outfall, and seepage, environmentally unsound and
unsustainable fishing practices, and just excessive
human visitation. And these problems must be, and are
being, addressed. But the biological world is very
complex and coral reefs are among the most
ecologically complex ecosystems that exist.

It has been demonstrated that return of Diadema to
stressed reefs improves coral ecology. For example
Carpenter and Edmunds (Ecology Letters, (2006) 0:
271-280 stated, “Here, we show that dense populations
of Diadema now occur over a multi-kilometer wide scale
at six locations scattered along a 4100 km arc across
the entire Caribbean. In all cases, these dense
populations are found in shallow water (<6 m depth) on
outer reef communities and are associated with reduced
macroalgal cover and enhanced coral recruitment. We
conclude that grazing by this echinoid is creating
conditions favoring the recruitment of coral.” And the
concluding statement in the paper by Precht and
Aronson, Death and Resurrection of Caribbean Coral
reefs, a palaeoecological perspective, (November 2005,
Coral Reef Conservation, Cambridge University Press,
Zoological Society of London, 2006). “
. recovery of
the sea urchin D. antillarum is probably the key to
facilitating coral recovery throughout the region.”
There are a number of other recent papers as well that
document and explore the phase shift from algae to
coral that occurs when Diadema return to the reefs,
significantly in Jamaica, where the reefs have been
long studied.

But as I mentioned, coral reefs are a very complex
ecosystem and “one size does not fit all”. I’m sure
that there are situations, especially in areas under
development and near population centers, where the
effects of herbivory would be greatly overshadowed by
human influence and effluence. Also the presence or
absence of complex reef structure influences the
success of Diadema establishment. Extensive complex
habitat greatly aids recovery of Diadema. (Habitat
complexity and consumer-mediated positive feedbacks on
a Caribbean coral reef Lee, 2006. and Rapid
Phase-Shift Reversal on a Jamaican Coral Reef. Idjadi,
Lee, Bruno, Precht, Allen-Requa, and Edmunds, Coral
Reefs (manuscript submitted Nov. 2005) Reestablishment
of Diadema populations in isolated areas where there
is little cover probably depends on the kind of
massive recruitment that can only occur when dense
populations are widespread over a great area. However,
all in all, recovery of Diadema where and when it can
occur is a very good thing for a coral reef.

However, as you mention there is the specter that the
forces of development and the political support that
developers acquire (buy?) can use loss of herbivory
and the potential to replace herbivory as tools to
create support for environmentally unsound
development. As deplorable as this may be, ignoring
and repressing research on the potential of returning
hervibory to Atlantic reefs because it may be used as
a development tool, is, to put it mildly, counter
productive. Return of herbivory is an important tool
in coral reef restoration efforts, but by no means the
only tool. 

I hope I have not given the impression that I am
arguing that there is no validity in the points you
have raised, this was not my intent for this is not
true. I know that repair of coral reef ecology is more
than just restoration of herbivory. My position is
that there are many stresses on coral reefs,
especially on our Florida reefs, that can not be
ignored, and loss of herbivory is one of the greatest
of them. We should do all that is possible to return
effective herbivory since that will improve the
ecology and resilience of the reefs and enhance coral
growth, settlement, and survival. And this should be
done in addition to efforts to reduce anthropomorphic
stress, and not at the expense of these efforts. I
think concentrating solely on either the “top down” or
“bottom up” concept of reef restoration would be a
mistake, because successful coral reef restoration
will require efforts from both directions. There must
be cooperation and collaboration in the science to
save what can be saved of our coral reefs.


--- "Dr. James M Cervino" <cnidaria at earthlink.net>

> Hi Martin,
> I know you are one of the best coral aquarium 
> specialists on the planet as you truly understand 
> the chemical interactions and mechanisms within a 
> closed system. However, I disagree with a few of 
> the comments that were posted below.  I am not 
> saying that Diademia grazing has no impact of the 
> abundance of macro-algae on a reef flat, however, 
> we must never ignore the more important impacts 
> of Nitrogen and Phosphorous above the thresholds 
> needed in a oligotrophic system such as a coral 
> reef (P. Bell,1992, Eutrophication and coral 
> reefs: some examples in the Great Barrier Reef 
> lagoon, Water Research, 26: 553-568; B. Lapointe, 
> & M. Clark, 1992, Nutrient inputs from the 
> watershed and coastal eutrophication in the 
> Florida Keys, Estuaries, 15: 465-476; B. 
> Lapointe, in press, Eutrophication thresholds for 
> macroalgal overgrowth of coral reefs, in K. 
> Thacker (Ed.) Protecting Jamaica's Coral Reefs: 
> Water quality issues; Goreau. T., 1992c, Coral 
> reef protection and coastal development in 
> Western Jamaica, p. 39-65 in K. Thacker (ed.), 
> Protecting Jamaica's coral reefs: water quality 
> issues, Negril Coral Reef Preservation Society, 
> Negril, Jamaica; Goreau, T., & K. Thacker, 1994, 
> Coral reefs, sewage, and water quality standards, 
> Proceedings of the Caribbean Water & Wastewater 
> Conference, Kingston, Jamaica) and to think that 
> grazing will control the will control the 
> abhorrent concentrations of nutrients that are 
> being released into coastal reef zones is 
> erroneous .
> When we fail to address "bottom-up" measures to 
> protect the habitat first and foremost,  all the 
> Diademia antiullarun in the Ocean Realm will not 
> be able to control the increasing macro-algae 
> forests that the worlds reefs of the new 
> millennium have evolved into. Myself and a 
> research assistant went to an MPA meeting 8 
> months ago on ManO War Cay (10km from  Guana Cay 
> ) where a few "experts"presented a "Top-Down" 
> action plan that will restore the fish 
> populations within designated locations in the 
> Abacos.  MPA plans, such as the one being 
> proposed in the Bahamas 8 months ago, tend to 
> favor the actions of the developers in Jamaica, 
> Bimini and Guana Cay instead of the protection of 
> the coral reefs from the bottom up in the decades 
> to come. 
> PS: Developers that want to build golf courses 
> will use this the nutrient debate in court as 
> they watch the coral list server and sort of turn 
> to it as a reference point.  Lets not allow 
> developers to think that the nutrient thresholds 
> published by the scientists quoted above can be 
> ignored, as this will give them reason to say 
> that the only reason reefs have shifted from 
> productive Cnidarian reef systems to macro algae 
> dominated habitats is due to the grazer 
> disappearing.
>   James
> >I am of course, referring to the restoration of
> >the keystone herbivore of the southwestern north
> >Atlantic, the sea urchin Diadema antillarum. It is
> >well documented that when Diadema return to the
> reefs
> >in large numbers, the phase shift from coral to
> algae
> >is reversed. There is much we don’t yet understand
> >about this fundamental ecological balance, but
> >aggressive research projects aimed at furthering
> this
> >understanding and developing the technology and
> >techniques for restoration of this keystone
> herbivore
> >should be pursued.  If we do this now, we can
> reduce
> >the rate of coral reef decline and hopefully buy
> the
> >time we need to fix the huge problems. OK, so I’m
> an
> >optimist.
> >
> -- 
> **************************************************
> Dr. James M. Cervino, MS, Ph.D.
> Marine Pathology
> Department of Biological & Health Sciences
> Pace University New York NYC
> Phone: (917) 620-5287
> Web site: http://www.globalcoral.org
> ***************************************************
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