[Coral-List] FW: RE: What is a coral reef and where is it's edge?

[Dennis Hubbard]

Robert's assessment that the definition of coral reef eliminates many thing
that should be considered "reef" is correct. However, it also lumps things
that are not "reefs" into that category as well. For this reason, I decided
a long time ago to discuss the question "what is a reef" only with friends
and in pubs.

The present spectrum of definitions make the term about as usual as calling
them "Bob". The challenge is to decide what FUNCTION we want to imbed in
our definition. Is is 3-D structure? Yes and no. Is it biodiversity? Yes
and no. Is it biologically produced? Well... that depends on what you mean
by "produced". Cores tell us that reefs tend to create structure (i.e.
accrete) at pretty much the same rate over the first 30-40m of water depth
and are not linked to coral-growth rates..... hmmmm! I know that's
counter-intuitive, but that's the data. So reef building, coral growth rate
and diversity are not as coupled as is widely assumed.

On another front, the same community on a flat bottom will provide
ecological services that are different from the same community on a highly
rugose surface. One might argue that the community is to some extent
limited by the topography... and, therefore, that the topography is also
determined by the community. The first seems to be the case while available
evidence argues against the latter. What does this tell us? I could
continue long after the most diligent members of the listserve hit the
delete button. So, the point is not that one definition is "better" than
another one, but more that we understand our generalizationswhen we define
reefs and think about how we extrapolate from what we choose to put into
that bin. A government definition is virtually guaranteed to violate all of
the above.

Dennis


On Mon, Aug 26, 2013 at 2:16 PM, Robert Bourke <rbourke at oceanit.com> wrote:

> In nature, is a coral colony always a subset of a coral community, and is
> a coral community always a subset of a coral reef?
>
> Because "coral reefs" are defined by federal regulation as a "Special
> Aquatic Site" they are provided special consideration during permitting.
>  99-percent of the time this is a very good thing.  However, it can lead to
> some absurd and costly rulings for little environmental gain when the
> regulation is enforced because of isolated corals growing on unusual
> substrates such as navigation structures, harbor facilities, or other
> structures not associated with the reef.  The special aquatic site
> regulations define a coral reef, using the word "reef" to describe itself:
>
> "Coral reefs consist of the skeletal deposit, usually of calcareous or
> silicaceous materials, produced by the vital activities of anthozoan polyps
> or other invertebrate organisms present in growing portions of the reef."
> (emphasis added).
>
> This would seem to infer that a pre-existing "reef" is required if a
> "coral reef" is to exist.
>
> >From a nautical perspective a "reef " is a hard typically abrupt physical
> uprising of the seafloor that ships can run aground on and is similar to a
> "shoal" which connotes a broader often soft bottom uprising of the
> seafloor.  Coral reefs are reefs built by hermatypic corals and associated
> organisms.. Deeper 3-D structures built by corals or other organisms
> (algae, worms, whatever...) are bioherms because they are neither
> associated with reefs or shoals.  It's unfortunate that "bioherm" doesn't
> bring to the mind the same romantic images as "coral reef."
>
> But the above definition eliminates many ecosystems that we all "know" are
> coral reefs from consideration as true coral reefs.  For me, the extensive
> deep Porites reefs off the Kona Coast that grow across the lava substrate
> at depths of 30-80 feet are definitely ecosystems worth protecting, but are
> not true reefs in the nautical sense or according to the definition under
> the special aquatic sites regulation.
>
> The EPA has recently come out with a method for slicing and dicing
> ecosystem types and services provided through the us of a numerical
> classification approach (Landers, et al, 2013  Ecosystem Services:
> http://ecosystemcommons.org/document/final-ecosystem-goods-and-services-classification-system-july-2013)  I challenge The List to develop an approach to "coral reef"
> classification that, similar to wetland classification systems or this new
> EPA approach, can allow any two scientists to arrive at the same
> classification of the same reef to better define its extend, boundaries,
> and quality.  More importantly it will allow all of us to use a common
> ruler to gauge the types, functions and values of reefs distributed across
> the world.
> Aloha
> Bob Bourke
> Environmental Scientist
> Oceanit
> Hawaii
>
>
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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*"