[Coral-List] Michael Risk - C. delitrix as measure of bioerosion

Derek Manzello dmanzello at rsmas.miami.edu
Tue Oct 17 14:45:41 EDT 2006

Hello Mike and coral reef enthusiasts,

I would like to point out a field observation valid to this thread. 
Boring sponges are statistically insignificant in the carbonate budget of
eastern tropical Pacific coral reefs (see countless references by Peter
Glynn and colleagues), albeit this entire basin is heavily influenced by
the upwelling of nutrient rich waters.  Echinoids (/Diadema mexicanum/ in
Panama and /Eucadaris galapogensis/ in the Galapagos) are the most
abundant and destructive bioeroders in the ETP and Lithophagine bivalves
are locally important particularly on heads of /Porites lobata/.  I am
dying to hear your thoughts on this Mike, because I know you have done a
little work with Lithophaga spp. in /Porites lobata/ off of Cano Island in
Costa Rica (showing the effect of the bivalves on coral strengh, or
resistance to stress before breaking).  I eagerly await your response.

I do agree with you that bioerosion is something we all need to be looking
into more especially now that many reefs have very low live coral cover
(i.e., Florida Keys), thus (agreeing with you), it is very likely these
reefs are now eroding rather than accreting.

Take care and I hope this creates disscussion,
Derek Manzello

> Hello Gregor.
> This response may be more than you had bargained for, but you asked for
> it. Part of what I have to say has just been covered by Christine
> Schoenberg?s post: Christine REALLY knows boring sponges, whereas I
> just dabble.
> It is gratifying to see interest in bioerosion now. That the coral reef
> biological community could so assiduously have ignored a process that
> controls their ecosystem is something that is beyond my ken-but then,
> so are a lot of things.
> Boring sponges are the main culprits. As their activities are
> accelerated by elevated levels of nutrients in surrounding waters, it
> is appropriate that they be included, where possible, in monitoring
> protocols.
> There are two species of possible interest, Cliona delitrix and C.
> orientalis (aka caribbaea, viridis, etc.) To begin with delitrix : the
> specific name comes from the Latin ?to destroy? (?Cartago delinda est,?
> etc), and has the same root as the Delete key on your computer. It is
> one of the few sponges having the ability to settle on live coral
> tissue, establish, and spread from there. (Most of the others have to
> land on bare substrate first.) More than 20 years ago, in the dark ages
> before pdf?s, we established a relationship between abundance of this
> sponge and amount of fecal bacteria in the water (Rose, C.S., Risk,
> M.J., 1985. Increase in Cliona delitrix infestation of Montastrea
> cavernosa heads on an organically polluted portion of the Grand Cayman
> fringing reef. Marine Ecology 6 (4), 345?363). Montastrea cavernosa
> continues to be its favorite prey/host, by the way.
> Since then, I have seen this sponge everywhere in the Caribbean where
> sewage pollution is a problem. Off the east coast of Florida, the
> characteristic ochre-red colour of C. delitrix colonies 10?s of meters
> in extent in shallow water may be seen from low-flying aircraft! In
> another recent example, I was trying to survey the fringing reefs of
> Grenada. I was in a small boat, a local kid (anyone under 40, in my
> case) guiding me. At one point, I found a large colony, explained to my
> guide what it was and why I was looking for it. He then took me to the
> next site. I was under water maybe 30 seconds, popped back up saying
> ?What the ****?? (not being able to use expletives on coral-list), to
> meet my guide grinning ear to ear. He had taken me to the bay receiving
> drainage from the town dump, which could not be seen from the boat: and
> I had just seen a reef on which close to every head was infested.
> In life, the critter is bright ochre-red. I will send you by separate
> email some photos: any other ?list readers may also request copies.
> Colony size ranges from tiny to very large: the biggest I have
> personally seen would be 2x3m (Florida Keys). Patches the size of an
> open hand are sometimes common. M. cavernosa is usually the first to be
> attacked, but eventually it will munch everything in sight. Sometimes
> it is colonised by white commensal zoanthids, the name of which escapes
> me (if I ever knew it).
> My first dive on the reefs of Florida was in 1960, and my eyes must be
> failing because it doesn?t look the same now. It has been said by some
> that the Florida decline is due to ?climate change.? This is
> politically- and economically-motivated pernicious foolishness, and
> should be challenged whenever encountered. In fact, a number of very
> fine scientists (Halas, Dustan, Shinn,...) have documented that the
> decline in Florida began in the 70?s, long before any wiggles in ocean
> temperature, upticks in pH, etc. Two previous works documenting the
> trajectory of the Caribbean-wide decline (Pandolfi et al, Gardner et
> al) also clearly show that the downward slide began some time ago, and
> that there is no notable recent acceleration correlating with any
> climate Hockey-Stick curve, or any other ?climate-change? related
> factor.
> Make no mistake: if climate change is not halted or reversed, it will
> in all likelihood slay every reef on the planet-but by then, what
> remains will be poor remnants of those glories some of us remember. No,
> if we wish to confront the real cause of the deaths of our reefs we
> need to look in the mirror when we flush the toilet (a riveting image
> if ever there were one.) To add to the body of evidence already in the
> literature, there is a growing mountain of evidence implicating
> nutrients/sewage/eutrophication. This thread was prompted by the
> discussion of the recent, and excellent, paper by Kuffner et al,
> showing how macroalgae inhibit coral settling. There was previous
> discussion of the Cline et al paper (MEPS 314: 119?125) on the impact
> of DOM on coral-inhabiting bacteria, and how this disrupts the
> coral-algal symbiosis. Brian Lapointe?s body of work simply cannot be
> ignored, and there is also corroborating work from biomarker studies
> (Downs et al, Environmental Forensics 7:15?32, 2006) and geochemical
> indicators (Ward-Paige et al, 2005: Mar Poll Bull 51: 570-579;
> Ward-Paige et al, 2005: MEPS 296: 155?163).
> In fact, the real question is: why coral reefs? Why are coral reefs the
> only ecosystem on the planet for which the impact of nutrient excess
> has to be proven again and again, seemingly in the face of implacable
> opposition? I stray from the focus of this posting, but I fear the
> answer may lie in the evil triumvirate of careers, CYA, and cash. Reef
> managers are reluctant to admit that the decline is due to local
> sources-it is much easier to blame ?global change?, the control of
> which is outside their job description.  In addition, as some posters
> have alluded, there is always a market for scientists who will say a
> given coastal development (golf course, marina, whatever) will have no
> impact because, after all, nutrients are unimportant.
> Back to The Destroyer. Christine Ward-Paige and I devised a
> quick-and-dirty scheme for FMRI by which amounts of C. delitrix could
> be estimated. Nothing special, a diver simply swims a transect line
> with a quadrat frame (25x25cm divided into 5x5cm squares works well),
> estimating area of delitirix. This takes next to no time. The problem
> with converting these measures to estimates of framework destruction is
> that colonies of delitrix are not two-dimensional. It frequently drives
> straight into the heart of the coral. Rose and Risk gives some idea of
> the variance involved in estimating rates from areas-but areas are a
> start, and it?s easy. Delitrix does not occur in the Indo-Pacific.
> The Indo-Pacific is easier, and more difficult. Easier surveying,
> harder identifying.
> There is a circum-tropical sponge that I have seen in every reef
> province I have dived. (Many years ago I published a wee paper pointing
> out that the boring sponge fauna really is worldwide, unlike the
> corals: the sponges are older, and what we see now is the remnant of a
> Pan-Tethyan distribution). It?s the same damn critter everywhere, with
> regional differences, but has been given a plethora of names: Cliona
> caribbaea, viridis, orientalis, langae, yadda yaddae. Christine has
> listed some of the synonyms.
> This sponge excavates down about 1cm, then spreads out over the surface
> removing about 50% of the substrate. It is therefore a two-dimensional
> critter, and area equals destruction. Previous studies (eg Acker and
> Risk, Caribbean; Bergman and Risk, GBR-on the GBR, it is the single
> most abundant benthic species on bommy walls) have shown it capable of
> removing material at 15kg/m2/year, or about twice the rate at which
> present-day Caribbean reefs calcify. So monitoring this guy with
> quadrats makes good sense.
> It?s harder to identify than delitrix, at least until you get your eye
> in. At first, it looks like an algal scum-the sponge has zooxanthellae,
> so it?s brown/olive in colour. If you look closely, however, you will
> see the oscula on the surface. These tend to be about 2mm diam, often
> raised a bit...sometimes, as I saw in the Banda Islands,  oscular rims
> are outlined in bright green for some unknown poriferan reason. Maybe
> SpongeBob knows.
> So there it is. Delitrix in the Caribbean, Cliona multiname everywhere.
> Enough. I?ve written papers that took less time than this posting-now I
> need to get in some firewood.
> Mike
> On Mon, 16 Oct 2006 19:48:02 -0700
>  "Gregor Hodgson" <gregorh at reefcheck.org> wrote:
>> Mike has long suggested the use of boring sponges as a useful/simple
>> technique for estimating one component of reef health. We are always
>> open to
>> good suggestions and this idea is appealing, however, our initial
>> tests did
>> not support the theory. To be useful to us, this indicator needs to
>> work at
>> least regionally if not globally. But we have not given it a rigorous
>> test.
>> We would be very pleased if Mike (or supporter) would suggest a
>> volunteer
>> level protocol and then if teams around the world might give it a
>> test to
>> see if it holds up as an indicator on a wide geographic scale.
>> Best,
>> Greg
>> Gregor Hodgson, PhD
>> Executive Director, Reef Check Foundation
>> P.O. Box 1057 (mail)
>> 17575 Pacific Coast Highway (Fedex)
>> Pacific Palisades, CA 90272-1057
>> Tel: +1-310-230-2371 Fax: +1-310-230-2376
>> email: gregorh at reefcheck.org
>> www.ReefCheck.org
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>> -----Original Message-----
>> From: coral-list-bounces at coral.aoml.noaa.gov
>> [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Jon
>> Rohde
>> Sent: Saturday, October 14, 2006 7:37 PM
>> To: coral-list at coral.aoml.noaa.gov
>> Subject: [Coral-List] Michael Risk - C. delitrix as measure of
>> bioerosion
>> Michael Risk
>> I have long wondered about the role of boring sponges which seem, to
>> my
>> unpracticed eye, to be ever more prevalent on Bahamian reefs - where
>> I spend
>> half the year.  As you note, there seems to be little attention to
>> them yet
>> they are relatively easily quantified by amateurs like me.  I have
>> joined
>> Reef Check and conducted surveys with their few indicator species to
>> document some Bahamian reefs, but wondered about the rapidly
>> increasing
>> algae and boring sponges which are neither counted nor mentioned in
>> this
>> simple methodology, but seem to comprise large portions of our reefs
>> biomass.
>> Could you give me some accessible references to C. delitrix and other
>> boring
>> sponges?  Do you think that their inclusion in standardized reef
>> surveys
>> would be a useful tool to document bioerosion?
>> Thanks for this interesting lead.
>> Jon Rohde, MD
>> 3 Moray Place
>> Orangezicht, Cape Town, 8001
>> tel 27-(0)21-465-0569
>> Cell 27 (0)83-306-7701
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> Mike Risk
> Marine Ecologist
> PO Box 1195
> Durham Ontario
> N0G 1R0
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