[Coral-List] deep "coral oases"

Dennis Hubbard dennis.hubbard at oberlin.edu
Wed Sep 16 14:18:19 UTC 2020

Thank you both. I still remember being a newly minted PhD at the reef
meeting in Tahiti. When I raised concerns over the emerging usage of the
term "reef growth" and the possibility that it would encourage us to
conflate coral growth and reef building, I was soundly admonished as being
pessimistic and naive. As a result, the distinction was absent from the
report. So....... here we are decades later having the same discussions. I
will end with the phrase that I suggested and was not adopted for inclusion
in the record of the breakout session......



On Wed, Sep 16, 2020 at 10:22 AM Alina Szmant via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Hi Doug:
> Well done. This could have been right out of the introductory lecture from
> my coral reef ecology course, which I taught for almost 30 years! I
> especially like that you clarify the 'shallow enough to be hit by a boat'
> part (most REEFS around the world are made up of non-coral rocks, not coral
> limestone), the term bioherm for deeper accumulations of biogenic skeletal
> matter (algae such as Halimeda form bioherms, e.g. Marquesas between Key
> West and Dry Tortugas; many places along the Great Barrier Reef in deep
> passes between coral reefs), and that a true coral reef needs to be
> accretional in nature not just scattered corals (i.e. net calcification >
> 1; limestone deposition > bioerosion). Some places that could form coral
> reefs don't because of the high rates of bioerosion (e.g. some upwelling
> zones).
> It is important that the growth history of any particular structure being
> considered for designation as a coral reef be carefully considered. I
> recall an article from years ago where a new volcanic outcrop was quickly
> colonized by corals. This could have been a founding event for a coral
> reef, but just high coral cover does not equal a coral reef.
> Best,
> Alina
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> -----Original Message-----
> From: Coral-List <coral-list-bounces at coral.aoml.noaa.gov> On Behalf Of
> Douglas Fenner via Coral-List
> Sent: Tuesday, September 15, 2020 6:13 PM
> To: coral list <coral-list at coral.aoml.noaa.gov>
> Subject: [Coral-List] deep "coral oases"
> Deep beneath the high seas, researchers find rich coral oases
> https://www.sciencemag.org/news/2020/09/deep-beneath-high-seas-researchers-find-rich-coral-oases
> Notice the title says "coral oases" not "coral reefs" and does not say
> "hard corals," but does say "rich."
> There are a number of distinctions that some popular articles such as this
> one tend to gloss over, and they tend to talk in ways that may lead people
> to assume that these places are similar to shallow tropical coral reefs,
> but that comparison is strained at best.  So, the original meaning of the
> word "reef" is a structure that is near the water surface that a boat can
> hit.  These are not reefs, they are in deep water.  Second, a coral reef
> would be a reef built by coral.  There are deep sea structures built by
> coral, some a few hundred feet tall and can be a mile or more long.  The
> most famous of which are in the fjords of Norway, but others are scattered
> around the world.  They are better termed "bioherms" since they are
> constructed by organisms, but don't get close to the surface.  People
> sometimes talk about their high diversity, but usually the construction is
> built by only one species of coral, while many shallow tropical coral reefs
> have hundreds of species of corals on them.  Plus, in the whole world,
> there are only a few species of coral that can build deep water
> constructions, maybe less than 10, and most or all are thin branching.  I
> suspect, but don't know for a fact, that the diversity of other organisms
> inhabiting them are also much lower than most shallow water tropical coral
> reefs.  But much of what they are probably talking about here are "coral
> communities" or ecosystems, as they are not constructional, there is no
> geological structure built by them  The photograph for this article shows
> many gorgonians, or octocorals, which can also be called soft corals, and
> which do not build calcium structures (surprisingly, there are
> non-gorgonian soft corals on shallow tropical coral reefs that add to the
> geological structure, in a few places their contribution can actually be
> greater to the construction than "hard corals" like Scleractinia).  Looks
> like there is at least one that may be a black coral, a group which also
> does not build coral reefs.  Among the hard corals, most are
> "scleractinia".  On shallow water tropical coral reefs, most scleractinia
> are zooxantellate, colonial and many large, and most contribute to building
> the geological structure, which can be up to at least 1.6 km (one mile)
> thick, depending on how long it has been building.  Scleractinian corals do
> certainly live in deep and/or cold water, and there are about as many
> species known that do that as on coral reefs.  They are all
> azooxanthellate, most are solitary and small, and by far most of them do
> not build any structures other than their own skeleton.  Often they are
> scattered.  That doesn't mean that they aren't interesting or important,
> just different.
>      So deep water or cold water coral bioherms are interesting, part of
> our world, as are deep water hard and soft coral communities.  They are
> generally less studied because they are much more difficult and expensive
> to access and study, and they are not restricted to warm, shallow water.
>       I don't study them, I'm not an expert on them, so those that are,
> please correct me if I'm wrong about this.
>      Cheers, Doug
> --
> Douglas Fenner
> Lynker Technologies, LLC, Contractor
> NOAA Fisheries Service
> Pacific Islands Regional Office
> Honolulu
> and:
> Consultant
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> The toxic effects of air pollution are so bad that moving from fossil
> fuels to clean energy would pay for itself in health-care savings and
> productivity gains <
> https://nature.us17.list-manage.com/track/click?u=2c6057c528fdc6f73fa196d9d&id=c9f70ba54f&e=190a62d266
> >
>> even if climate change didn’t exist.  In the US alone, decarbonization
> would save 1.4 MILLION lives in the US alone.  And save $700 Billion a year.
> https://www.vox.com/energy-and-environment/2020/8/12/21361498/climate-change-air-pollution-us-india-china-deaths
> "mitigating climate change is the critical wedge to set coral reefs on a
> recovery trajectory"  Duarte et al 2020 Rebuilding marine life Nature
> "Already, more people die  <http://www.nws.noaa.gov/om/hazstats.shtml>from
> heat-related causes in the U.S. than from all other extreme weather
> events."
> https://www.npr.org/2018/07/09/624643780/phoenix-tries-to-reverse-its-silent-storm-of-heat-deaths
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Dennis Hubbard - Emeritus Professor: Dept of Geology-Oberlin College
Oberlin OH 44074
(440) 935-4014

* "When you get on the wrong train.... every stop is the wrong stop"*
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