[Coral-List] Porites lesions, hardship vs. disease, climate change, and conservation investments
lesk at bu.edu
Sat Jan 12 11:30:17 EST 2008
Thanks for posting the Gulf of Suez PLD photos, Zaki (http://
Everything posted there but the WL shots (see Julian's comment re:
Cuthona poritophages) look like they could have been fish or other
predator bites followed by stress response and progressive necrosis
whose detailed dynamics are still unknown.
I have a suggestion that could help to resolve this. I suggest an
experiment. That is, be the fish, make some marks, see what
happens. It might also pay to try the idea that some of us have
discussed, of lesioning the coral with sterile tools versus the
actual jaws of some Arothron or appropriate parrotfish fresh-caught
from the vicinity (this can theoretically be done without harming the
fish, using anesthetics). That is, we must remember that fish don't
floss, and corals may not like being kissed by them for good reason.
Then document the process of lesion repair in a quantitative manner,
preferably including histology and microbiology. Fully understanding
the process of regeneration from abiotic or biotic mechanical damage
can help us in distinguishing between this and purely microbial or
viral etiologies. We realized this back in the 70's and 80's during
the early days of confusion over what was or wasn't a coral disease,
and Esther Peters, Andy Bruckner and others helped us out of that jam
This is not a radically new idea.
In the MMAS program (www.conservation.org/mmas) we are testing the
hypothesis that chronic stress causes a failure in the normal healing
process of corals, with the thought that this plays a major role in
effecting extreme and recalcitrant drops in coral cover on a reef
(sometimes referred to as a "phase shift"). Under ideal conditions,
the healing process of corals permits rapid recovery from routine
damage by predators, endolith eruption, mechanical abrasion, algal/
microbial allelotoxic effects and so forth.
Under chronic stress, this recovery is impeded and may be supplanted
by progressive necrosis. We postulate that the stresses involved
include the usual litany of local stresses from the watershed
(sedimentation, terrestrial contaminants, limiting nutrients,
pathogens) and on the reef (e.g. grazer reduction favoring overgrowth
by competitive invertebrates, algae, and hostile microbial
consortia), plus global stresses such as thermal anomalies and plague-
like pathogens (think perhaps Caribbean acroporids).
One practical import of making these distinctions is that they permit
us to calculate the marginal benefits of local conservation efforts.
In other words it helps us to empower local conservation and make the
appropriate local investments while also acknowledging the global
forces that can not be dealt with effectively at the local level.
Another way of putting this, from a climate change perspective, is
that the local conservation efforts are an important part of adaptation.
We proposed use of an artificial lesion assay to quantify this
process in a standardized fashion. We were inspired by the work of
Rolf Bak and Erik Meesters; I used this approach also to study
damselfish "chimneys". Cheryl Woodley and her colleagues have also
been working in this direction for some time to good effect. Erich
Mueller plans to present the MMAS version of this for Montastrea
faveolata at ICRS. Erich's work is in turn linked to experiments now
being run on the same coral by Chris Langdon, in which we examine
lesion repair under different aragonite saturation states to look at
the interaction between pCO2 and the lesion repair process. The idea
is to focus on the resilience of coral colonies, as a key to
understanding space occupation on coral reefs. It is the complement
to studies of coral and coralline algal recruitment, and axial
extension (growth). All three (recruitment, growth, repair) must be
understood to grok surface dynamics on what we still dare to call
"coral" reefs. The third component in our work is the study, at the
microscopic and molecular levels, of coral stress and regeneration.
Our (MMAS) contributions in this area are being led by John Finnerty
and Forest Rohwer, but here, too, we work as contributors to a
community effort, with different labs attacking the problem with
varied methodologies and from different points of view.
Our MMAS group is just one among several who share this big picture
view. Of course there are also folks like Ove H-G, Andrew Baker, and
James Cervino who have been looking at the zook end of things.
Together we can lick this, and possibly fairly quickly, like over the
next few years. By "this" I mean to understand how we can best
foster the resilience and reestablishment of healthy coral reefs on a
large scale, in a world that we have made hostile to this outcome.
Regarding the pigmentation in the photographs, some corals, like
these Pacific poritids, "light up" when healing (i.e., they
concentrate visual-bright and sometimes also flourescent pigments at
the lesion periphery), so they light up big time when a lesion
festers and elaborates. This is what Laurie was alluding to.
Professor of Biology
Boston University Marine Program
Marine Management Area Science
“I know the human being and fish can coexist peacefully.”
George W. Bush
Saginaw, Michigan; September 29, 2000
More information about the Coral-List