[Coral-List] Fwd: Giant barrel sponges taking over Florida's reefs!

Douglas Fenner douglasfennertassi at gmail.com
Fri Sep 4 16:46:12 EDT 2015

    Good point.  The geological reef structure was built by primarily by
corals, or at least the corals are important as baffling to hold it
together.  Algae often are very important contributors and can contribute
more calcium than corals.  They are coral reefs in the same sense as a
similar structure lifted 20 feet out of the water 100,000 years ago is a
coral reef.  But an uplifted reef above the water does not have a living
coral reef ecosystem on the surface.  The same is true of reefs that are
now dominated by algae, whether the algae is macroalgae (by which I mean
frondose or fleshy algae) or turf (by which I mean filamentous algae) or
coralline algae or mixtures or soft corals or other things.
     Sometimes people talk or write about how reefs may die in coming
decades.  The geological structures won't die, though they have many living
things in holes in the structure, I would think.  I don't think the
geological structures are going to disappear in a few decades, either.  I
presume that reefs in Florida that are now sponge-dominated instead of
being coral-dominated are not accumulating more calcium deposits, likely
they are loosing more than gaining, bioerosion likely is greater than
calcification (unless there are algae calcifying faster than the
bioerosion).  But I'm not as worried about the geological structure as the
ecosystem, in the relatively short term (decades).
      I have sympathy for Mike Risk's view of the need for something
besides just ecologists, studying reefs.  I tend to think that with the
vast expansion of knowledge, individuals have to specialize.  I read
somewhere that about 1800 papers on coral reefs are being published each
year now and the rate is increasing fast.  No one can keep up with all of
it, and time spent outside of your specialty means less time to gain the
knowledge to be a competitive expert in your specialty.  So trying to be a
generalist is pretty self-defeating.  The answer is to have teams of people
with different specialties, because as Mike rightly points out, coral reefs
are very complex structures with many different things that require
different specialists to study, and many reef aspects need people in
several different specialists to study.  We already need statisticians on
our teams.  I agree ecologists probably need to work with geologists in
their teams more often.  I think ecologists need to consult with
taxonomists about identifications of their favorite organisms more often,
and geneticists need taxonomists on their teams.
      But I also think that the coral reef crisis is an ecological crisis,
not really a geological crisis.  Oh, it will be in a few thousand years if
we keep this up.  But we are loosing coral reef ecosystems even if we
aren't loosing geological structures yet.  Both provide benefits for
humans.  But the scientific community is pretty nimble at shifting towards
the exciting parts of science, and a lot of people see the coral reef
crisis as important and so makes for exciting science.  Easier to get
funding on things important to society, so some of us shift to work on
those things.  Not a bad thing.
      But I think you're right, Vassil, to be accurate, in some places,
what was a coral reef ecosystem is now a sponge-algal ecosystem on top of a
dead coral reef.  Or something like that, I'm not sure what the best name
is.  Likely people will continue to call them "coral reefs" because that is
a catchy name that we are all familiar with.  There is one on the south
side of Molokai Island in Hawaii which had a wide reef flat, a reef made of
calcium carbonate.  The geological structure of carbonate is still there,
but the reef flat is almost completely covered with mud that has eroded off
of agricultural fields on land.  A few tiny corals poke up through the
mud.  I saw similar along the east side of Lanai Island in Hawaii a couple
decades ago.  What should we call that?  Certainly that reef flat does not
have a coral reef ecosystem.  Mud ecosystem on top of a dead coral reef is
more like it.
    In truth, many of the ecosystems we call coral reef ecosystems are not
actually dominated by corals.  Corals are an important component, but not
dominant.  True even on many reefs with very little human influence.  Of
course humans have caused massive losses of corals on many or most of the
world's reefs.  Of course that's bad.
    By the way, I LIKE sponges!  Caribbean sponges are large, colorful, and
their biology is very different and interesting.  Where I'm at in the
Pacific, sponges are small, uncommon, and cryptic.  Nothing like the
glorious sponges of the Caribbean.  They are not completely incompatible
with corals.  Cozumel used to have good coral on top of the reefs, and
fabulous sponge communities on overhangs.  Spectacular.  Wonderful part of
the ecosystem.
     Cheers,  Doug

On Wed, Sep 2, 2015 at 12:19 AM, Vassil Zlatarski <vzlatarski at gmail.com>

> Well, Joseph, in such case the usage of “coral reefs” should be precised,
> for example, "coral-limestone reefs" or “dead-coral reefs” or
> “not-living-coral reefs” or in other appropriate way.
> Best,
> Vassil
> Vassil Zlatarski
> D.Sc. (Biology), Ph.D. (Geology)
> ---------- Forwarded message ----------
> From: Pawlik, Joseph <pawlikj at uncw.edu>
> Date: Wed, Sep 2, 2015 at 5:31 AM
> Subject: RE: [Coral-List] Giant barrel sponges taking over Florida's reefs!
> To: Vassil Zlatarski <vzlatarski at gmail.com>
> Agreed, Vassil,
> But the reef was built by coral (it's limestone) -- they just aren't
> building it anymore!
> **************************************************************
> Joseph R. Pawlik, Professor
> Department of Biology and Marine Biology
> UNCW Center for Marine Science
> 5600 Marvin K Moss Lane
> Wilmington, NC  28409   USA
> pawlikj at uncw.edu; Office:(910)962-2377; Cell:(910)232-3579
> Website: http://people.uncw.edu/pawlikj/index.html<
> https://mail.uncw.edu/owa/UrlBlockedError.aspx>
> PDFs: http://people.uncw.edu/pawlikj/pubs2.html<
> https://mail.uncw.edu/owa/UrlBlockedError.aspx>
> **************************************************************
> ________________________________
> From: Vassil Zlatarski [vzlatarski at gmail.com]
> Sent: Wednesday, September 02, 2015 4:25 AM
> To: Coral-List Subscribers; Pawlik, Joseph
> Subject: Re: [Coral-List] Giant barrel sponges taking over Florida's reefs!
> Dear Coral-Listers,
> Prof. Pawlik offered interesting paper “Population dynamics of giant barrel
> sponges on Florida coral reefs” and video adding to the growing evidence
> that reef-building corals are declining and sponges are becoming the
> dominant inhabitants of modern Caribbean benthic communities.  For the
> fortunate researchers of coral reefs 4-5 decades ago is strange the usage
> of “coral reefs” for the documented now-existing situation.  Is it not in
> reality a case of “sponge gardens”?
> Cheers,
> Vassil
> Vassil N. Zlatarski
> D.Sc. (Biology), Ph.D. (Geology)
> On Tue, Sep 1, 2015 at 10:45 AM, Pawlik, Joseph <pawlikj at uncw.edu<mailto:
> pawlikj at uncw.edu>> wrote:
> Greetings, Colleagues,
> In a 12-year study just published in the Journal of Experimental Marine
> Biology and Ecology, we report that populations of giant barrel sponges
> have increased by 122% since 2000 on Conch Reef, off the coast of Key
> Largo, Florida. This adds to the growing evidence that sponges are becoming
> the dominant inhabitants of modern Caribbean reefs.  The article can be
> downloaded for free:
> http://authors.elsevier.com/a/1RcjD51aUK0hE
> Giant barrel sponges (Xestospongia muta) are found throughout the
> Caribbean, and commonly grow to the size of an oil drum or larger. Called
> the "redwoods of the reef," these sponges can live to be hundreds, even
> thousands of years old, based on earlier growth studies conducted by the
> same first author, Dr. Steven McMurray.
> A video tour of the plots on Conch Reef can be seen here:
> https://youtu.be/qdjhm7ojGJk
> You can see how large these sponges get in this video from the Bahamas:
> https://youtu.be/8WaWVuGE-LM
> Not only are the numbers of giant barrel sponges increasing, so is their
> volume, with a 39% increase since 2000. On average, each square meter of
> Conch Reef now has about 2 liters of barrel sponge tissue on its surface,
> more than any other organism on the reef.  And the giant barrel sponge is
> only one of many species of sponges that populate Caribbean coral reefs.
> Much of the increase in the numbers of giant barrel sponges was due to
> recruitment - the successful establishment of baby sponges. On some plots,
> the increase in the smallest-sized barrel sponges was over 600% for the
> period 2000-2012. And while the survival of larger barrel sponges was
> stable for the first half of this period, it increased during the second
> half, perhaps because of the absence of hurricanes over that time period.
> When hurricanes pass over reefs, large sponges can be damaged and
> dislodged, often resulting in mortality.
> Regards,
> **************************************************************
> Joseph R. Pawlik, Professor,
> Dept. of Biology and Marine Biology
> UNCW Center for Marine Science
> 5600 Marvin K Moss Lane
> Wilmington, NC  28409
> Office:(910)962-2377<tel:%28910%29962-2377>; Cell:(910)232-3579
> <tel:%28910%29232-3579>
> Website: http://people.uncw.edu/pawlikj/index.html
> PDFs: http://people.uncw.edu/pawlikj/pubs2.html
> Video Channel: https://www.youtube.com/user/skndiver011
> **************************************************************
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Douglas Fenner
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