deepwater coral "reefs"?

Pam Muller pmuller at
Thu Jun 1 10:28:56 EDT 2000

I concur wholeheartedly with Alina and would add a couple of small details.

A coral is either zooxanthellate or azooxanthellate in most cases (one can find exceptions to any "rule").  However, a coral is not inherently "hermatypic" or "ahermatypic".  Rather, whether coral can accrete limestone faster than it is eroded away or buried by a variety of processes is a function of the environment, in addition to the organism's accretion potential.  For example, Montastrea spp. are hermatypic in the Caribbean, but not on the West Florida Shelf.  There are also many local environments in the Caribbean where Montastrea can live but not construct bioherms.

This distinction is critical to conservation efforts, because a management decision to maintain environmental conditions that can support survival of Montastrea, for example, could be quite different than a management decision to maintain environmental conditions that can support reef (meaning "bioherm") development.

Pamela Hallock Muller, Professor
Department of Marine Science
University of South Florida

"Alina M. Szmant" wrote:

> Eric:
> The definition of a bioherm is a herm (mound) made by living organisms. It can be located in shallow, deep, or intermediate depths. Again, a "reef" is "a chain of rocks or ridge of sand at or near the surface of water" or "a hazardous obstruction" (Webster's New Collegiate Dictionary). Neither has anything to do with corals or zooxanthellae specifically.
> Coral reefs are bioherms or reefs made by corals and associated organisms. For the most part, hermatypic corals have zooxanthellae, but many zooxanthellate corals either do not live on or form reefs, or live on reefs but are not really a major contributor to reef formation (e.g. Favia fragum...).
> The confusion in terminology is due (1) to the misconception that hermatypic means zooxanthellae-containing, and (2) that everyplace there is coral there is a coral reef. Corals can have high cover on a volcanic substrate but that doesn't make it a coral reef in my opinion unless there has been carbonate accretion over the volcanic substrate. Further, in places like Florida, there is some coral cover over exposed Pleistocene reef substrate, which locally are considered coral reefs (as opposed to a coral community growing over a fossil reef). Everyone wants to have a coral reef in their back yard and many systems that are not true "coral reefs" are being called by that name.
> With regard to "deepwater" coral reefs, the only ones that would fit a strict definition would be ones that were drowned (e.g. Conrad Neumann's give-up reefs). Catch-up reefs would also fit since they are usually grow into shallow water. As ships get bigger and have deeper hulls, I guess the "dangerous obstruction" part of the reef definition would include deeper water coral reefs that big ships could run into. If we include submarines, then all depths are fair game....
> Anyway, that is how I analyze the terminology based on first principles and dictionaries.
> Alina Szmant
> 53 AM 05/27/2000 -0400, EricHugo at wrote:
> >Hi Alina and coral-list:
> >
> >Is there a point when a correct usage of "bioherm" over "reef" for such
> >structures became semantically favored? I ask because I find the following
> >perhaps relevant:
> >
> >Coates, Anthony G. and Jeremy B.C. Jackson. 1987. Clonal growth, algal
> >symbiosis, and reef formation by corals. Paleobiology 13(4) 363-378.
> >
> >(I will not quote directly to avoid copyright concerns, although I also hope
> >that the authors will point out if my translation is incorrect or improper,
> >although I maintain the textual use of the word "reef" and "bioherm" ).
> >
> >"Rugosan corals that formed reefs likely lacked zooxanthellae because of
> >morphological evidence. Most zooxanthellate corals today and in the fossil
> >record contribute to reef formation, but many others are ahermatypic. Recent
> >reef formation has little to do with being zooxanthellate but depends on
> >environmental factors. Using morphology to indicate the presence of
> >zooxanthellae, there exist recent deepwater analogues to the shallow water
> >azooxanthellate Devonian Edgecliff Bioherm. "
> >
> >Here we have a concatination of terms, distribution, history, and ecology
> >that makes this thread all the more intriguing.
> >
> >Thanks for the clarification
> >
> >Eric Borneman
> >
> >
> *******************************************************************
> Dr. Alina M. Szmant
> Coral Reef Research Group
> Professor of Biology
> Center for Marine Science
> University of North Carolina at Wilmington
> 1 Marvin K. Moss Lane
> Wilmington NC 28409
> tel: (910)962-2362 fax: (910)962-2410
> email: szmanta at
> ******************************************************************

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