[Coral-List] The GBR is in trouble, but not dead
dennis.hubbard at oberlin.edu
Sat Mar 25 16:23:08 EDT 2017
Regarding Chris' post, my recollection of the evolutionary classification
of GBR reefs was an extension of Conrad Neuman's idea of "keep-up",
"catch-up" and "give-up" reefs in the mid 70s. Initially, I think it was
Peter Davies who looked at relationships between GBR reefs and sea-level
rise with the idea that, eventually, GBR reefs caught up as sea level
slowed about 6-7,000 years ago. As a result, their accretion rates slowed.
In the process, they filled up the space on top of the reef crest and
vertical accretion (the only dimension we see in most cores) slowed down.
As a result, they developed broad reef flats that are so characteristic of
the GBR and the Indo-Pacific.
This was complicated by "equatorial siphoning" as water was transported
from the southern hemisphere to its northern counterpart. This was related
to glacial dynamic too complex to explain here, but the end result was that
local sea level has been constant (or dropping) for the last 6,000 years
near many/most GBR and Indo-Pacific reefs while it has slowed but continued
to rise in the Caribbean. The end result has been very different
accretionary histories in the two provinces. Caribbean reefs have tended to
keep more of their carbonate on forereef slopes (vertical and seaward
expansion) while GBR and Indo-Pacific reefs have tended to move much more
reef-crest material into the lagoon behind (lateral expansion). Those
"senile" GBR reefs were physiologically no different than their Caribbean
counterparts. Rather, the difference in accretionary (not coral-growth)
styles was solely a result of differences in the balance between the
creation of "accommodation space" (i.e., a place to put "new reef") as sea
level rose and the ability of carbonate production to fill it up.
The bottom line here is that using terms (aka "mature" or "senile", etc.)
that suggest biological responses (and controls) lead us to ignore
responses that have more to do with sea level than to "production capacity"
or "life-cycle". Corals "grow".... reefs "build". The two are intimately
related but by no means identical. Corals grow in response to
physio-chemical factors to which we collectively attribute "reef health".
However, the three-dimensional changes in reefs is related as much (and
probably more) to physio-chemical ocean processes that have less to do with
calcification that we generally assume.
On Fri, Mar 24, 2017 at 8:15 PM, Douglas Fenner <
douglasfennertassi at gmail.com> wrote:
> And that takes me back to my point, that reefs (Calcium buildups) are not
> alive. Can a piece of basalt or granite be "senile"? A better analogy
> than granite would be a stalactite. As water carrying super saturated
> CaCO3 percolates down though cracks in rocks above a cave, it runs in tiny
> trickles down the sides of stalactites and CaCO3 precipitates on it and
> adds to the formation. So the stalactite gets larger and people may say it
> "grows." But it is not alive, "grows" is only an analogy. Water stops in
> drought, stalactite no longer gets larger. Is it "senile"? Did it just
> "die"? If new water comes that is pure rainwater, it will start to
> dissolve the stalactite, which will get smaller. Is it "dying"? No. You
> can't die if you're not alive. You can't be "senile" unless you are
> alive. Rocks aren't senile, they don't die. Living organisms die,
> inanimate objects don't. Can granite get up and dance? Reproduce? I
> don't think so, and these terms are misleading, especially to those who
> don't realize the difference.
> Cheers, Doug
> On Thu, Mar 23, 2017 at 2:30 AM, Chris Perry <chris.t.perry at gmail.com>
> > Hi, I rarely dip my toe into this forum, but just to add that I think
> > reef geomorphologists quite like the term senile to describe such
> > situations of reefs ceasing to accrete (or senescent is favoured by some
> > and has been suggested to me by some reviewers). It is, however, also
> > saying that this term was actually first (as far as I know) used back in
> > the early 1980's by David Hopley in his classic book on the GBR - this in
> > the context of describing the evolutionary states of GBR reefs ... so it
> > a term now well grounded in the literature.
> > Cheers
> > Chris
> > Geography,
> > Amory Building,
> > University of Exeter ,
> > Exeter, EX4 4RJ
> > Message: 1
> > Date: Wed, 22 Mar 2017 10:51:38 -0400
> > From: Eugene Shinn <eugeneshinn at mail.usf.edu>
> > Subject: [Coral-List] he GBR is in trouble, but not dead
> > To: "coral-list at coral.aoml.noaa.gov" <coral-list at coral.aoml.noaa.gov>
> > Message-ID: <ec30b25d-bb3f-2803-c2bc-616e206e92b8 at mail.usf.edu>
> > Content-Type: text/plain; charset=utf-8; format=flowed
> > Ellen Prager points out a significant problem when dealing with the
> > press.If you are not careful you can easily get burned by an over
> > zealous environmental writer and headline writer. She rightly makes the
> > point that headlines for a story are often written by specialist other
> > than the writer who wrote the story. The headline is written to grab the
> > attention of the reader. Remember they are also in the business of
> > selling newspapers and as the reader knows, readership is suffering and
> > newspapers are going out of business almost daily. Some years ago I was
> > badly burned by some lurid headlines. At that time writers received
> > extra cash if the Associated Press picks up their story and passes it on
> > to other newspapers.Each paper that picked up my story about the effect
> > of sewage nutrients on coral reefs created ever more eye-catching
> > headlines. ?Sewage killing reefs scientist says.? The results were
> > unhappy calls from dive shop owners in the keys whose dive trips were
> > being cancelled because clients did not want to dive in poop. It was
> > most embarrassing.
> > Reef researchers have for years wrestled with how to define reefs.
> > Biologists and geologists see reefs differently and the average reader
> > can become confused by terms like bioherm, biostrome, or even live rock.
> > Remember when that big tanker grounded on ?Bligh Reef? in Cook inlet
> > Alaska? So-called Bligh reef is simply a submerged mountaintop. It is
> > not a reef but the confusion affected people in the Florida Keys who did
> > not know the difference. Even sandbars have been called reefs. In fact
> > anything that a ship can ground on is often called a reef. It?s just
> > maritime lore.
> > We discuss this problem in detail in our upcoming book, ?Geology of the
> > Florida Keys,? coauthored by Barbara Lidz. In the book we invented a
> > term for dead or almost dead reefs originally used by Lidz in her
> > extensive USGS review of Florida Keys Geology,
> > <http://pubs.usgs.gov/pp/2007/1751> For lack of a better term we called
> > reefs no longer growing ?senile reefs.? We can?t predict what a news
> > writer might do with that term but we could not think of anything better
> > at the time. As many readers know, Florida reefs are indeed suffering
> > senility. Hopefully most will recover their former vitality. It will be
> > interesting to see what a news writer might do with those terms, or for
> > that matter, readers of the coral-list. Lets see, ?Reefs in the keys
> > can?t think straight? or ?they forget who they are.? Gene
> > _______________________________________________
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> > Coral-List at coral.aoml.noaa.gov
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> Douglas Fenner
> Contractor for NOAA NMFS, and consultant
> "have regulator, will travel"
> PO Box 7390
> Pago Pago, American Samoa 96799 USA
> phone 1 684 622-7084
> Join the International Society for Reef Studies. Membership includes a
> subscription to the journal Coral Reefs, and there are discounts for pdf
> subscriptions and developing countries. Coral Reefs is the only journal
> that is ALL coral reef articles, and it has amazingly LOW prices compared
> to other journals. Check it out! www.fit.edu/isrs/
> "Belief in climate change is optional, participation is not."- Jim Beever.
> "Everyone is entitled to their own opinion, but not to their own facts."-
> Daniel Patrick Moynihan.
> Study: Stopping global warming only way to save coral reefs.
> 'Extreme and unusual' climate trends continue after record 2016.
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