[Coral-List] Reef accretion

Dennis Hubbard dennis.hubbard at oberlin.edu
Thu Apr 30 10:16:28 EDT 2015

Hi Eduardo:

Assuming that you are referring to actual "reef accretion" and not "coral
growth" (aka linear extension, calcification, density), the only practical
way is to examine Holocene core data. The obvious flaws in this approach
1) it can be difficult to constrain things like paleo-water depth and the
rate of sea-level rise at the time of each measurement, and
2) these rates occurred at a time when anthropogenic stresses were largely

The first can be dealt with if you can constrain LOCAL sea level rise. Sea
level history is different from place to place for a variety of reasons and
reefs responded to local controls (other than large scale acidification,
warming,etc. that we are seeing today - which also vary from site to site).
More difficult is the issue of figuring out what those reefs would have
done were the kinds of stresses we see today in play throughout the
Holocene. However difficult this might be and however imperfect the
geologic record is, it remains as the only pre-Homo stupidus record that we
have. In the words of Wendell Berry, "We cannot know what we are doing
until we know what nature would be doiing if we were doing nothing."

If you plan to place permanent markers and measure vertical changes in
relation to them (re: "We have a "plan" to measure the proccess"), this is
flawed on many fronts. First, accretion varies significantly from place to
place even on a single reef and I'm not sure you could set up enough to get
a statistically meaningful number. Second, the temporal scale of such
measurements will probably not allow you to use even numerous stations to
characterize patterns over time. There is so much of what looks like
randomness on the scale of such measurements, that it would be unwise to
put a lot of faith in even multi-year measurements. Every time discussions
are started about what is "good" and "bad" for reefs, those of us who have
spent a lot of time at marine labs end up being the contrarians as we have
seen so much temporal and spatial variability (coral where there used to be
none and vice versa) that we have come to not trust broad statements cased
on well-designed but short-term experiments.

If you want to share what you have in mind, it might be possible to "fine
tune" the method to the point where you could get good data that could be
used for management purposes. However, I suspect that this is going to be a
long, upstream swim.



On Tue, Apr 28, 2015 at 11:15 AM, Edgardo Londoño-Cruz <
edgardoloncruz at hotmail.com> wrote:

> Dear coral-listers,
> We are planning to conduct an investigation regarding reef accretion. We
> have done some research on the literature trying to find the best way to
> measure this process; however, the success on this quest has been
> relatively poor. Hence, I am wondering if anyone in the list could provide
> some guidance.
> Cheers,
> EdgardoDepartment of BiologyUniversidad del ValleCali, Colombia
> PS. We have a "plan" to measure the proccess  and could share it to those
> interested in the subject.
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> Coral-List at coral.aoml.noaa.gov
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Dennis Hubbard
Chair, Dept of Geology-Oberlin College Oberlin OH 44074
(440) 775-8346

* "When you get on the wrong train.... every stop is the wrong stop"*
 Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"

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