[Coral-List] COT current status
dfenner at blueskynet.as
Sat Jan 17 16:25:37 EST 2009
The reason you haven't seen larval or newly recruited COTS may be that
they live in holes in the reef eating coralline algae until they reach a
stage when they can eat corals, at which time they start coming out of the
holes at night only until they are larger. It is about 3 years from a mass
larval settlement to adults suddenly appearing in daytime, which is why
Birkeland found the correlation between outbreaks and heavy rainstorms 3
years earlier following dry periods on high islands (which produce nutrient
I believe the only evidence supporting the theory that humphead wrasse
eat COTS may be a single COT found in the stomach of one humphead wrasse
reported in an early study by John Randall. Someone may be able to correct
me on that. There is a paper Dulvy, N.K.,
Freckleton, R.P., and N.V.C. Polunin. 2004. Coral reef cascades and the
indirect effects of predator removal by exploitation. Ecol. Letters 7:
410-416. that reports fishing is correlated with higher COTS populations.
But the measure of fishing pressure was human population per km of reef, and
that is also likely to correlate with nutrient runoff, which is a known
cause for outbreaks.
Did I catch that COTS were common not only where aquarium fishing was
occurring, but also other places that had nutrient runoff?? Your culprit is
more likely nutrient runoff than aquarium fishing, I think.
A variety of species on reefs other than COTS have population booms,
such as the recent reports of huge pulses of recruitment of various reef
There is a whole literature on algae, herbivores, and phase shifts. Not
having herbivores in an area with nutrient runoff and COTS killing corals
sounds to me like a sure recipie for a phase shift to algae that will be
hard to get back from. You are right that the phase shift is not the COTS
fault, they are just the trigger, could as easily be anything else that
kills coral. A place with nutrient input and few herbivores is a phase
shift waiting to happen. If aquarium fishing removes herbivorous fish, it
could contribute to that, but I doubt it removes very many herbivorous fish,
they would be hard to feed in an aquarium (someone correct me if I'm off
track there). There are many reviews of the algae-coral problem and phase
shifts, a recent one is Birrell et al 2008. Effects of benthic algae on the
replenishment of corals and the implications for the resilience of coral
reefs. Oceanography and Marine Biology: An Annual Review 46:; 25-63.
Do you have:
Brodi et al 2005 Are increased nutrient inputs responsible for more
outbreaks of crown-of-thorns starfish? An appraisal of the evidence.
Marine Pollution Bulletin 51: 266-278.
Sweatman, H. 2008. No-take reserves protect
coral reefs from predatory starfish. Current Biology 18 (14) R 598-R599.
Houk et al 2997. The transition zone chlorophyll front can trigger
Acanthaster planci outbreaks in the Pacific Ocean: historical confirmation.
Journal of Oceanography 63: 149-154.
Birkeland, 1989. The Faustian traits of the crown-of-thorns starfish.
American Scientist 77: 154-163
I, and perhaps some others on coral-list, would be interested in the
references to the papers on the research you talk about. Thanks! Doug
----- Original Message -----
From: "Karl & Michele" <michka at fellenius.net>
To: <Coral-List at coral.aoml.noaa.gov>; <info at crcreef.com>
Sent: Thursday, January 15, 2009 3:23 PM
Subject: [Coral-List] COT current status
> Dear coral list and CRC,
> I have been looking at the 2003 CRC info doc on crown of thorns at
> www.reef.crc.org.au/publications/brochures/COTS_web_Nov2003.pdf as well as
> few other web publications.
> I do environmental assessments in Vanuatu and currently there is a COT
> outbreak on Efate. I am seeking fairly specific references to published
> works on linkages between nutrients, algae and COTs. Not so much from a
> coastal run-off perspective but more related to harvesting of herbivores
> omnivores in the aquarium trade. Efate has an very active fish and
> invertebrate export. COT outbreaks are occurring in their collection areas
> as well as a number of other areas. I realise there are numerous factors
> play. Last year this was a fairly heated topic here with many differing
> opinions and official responses denying any connections between the trade
> and COTs. However, both 'outbreaks' continue on Efate ...
> I have been asked by a group made up of villagers, ex-pat residents, and
> others seeking answers to these questions to do what I can. My background
> such that I believe these hypotheses to be true, although I have not
> out the research. I trust that others have. After last years' mess on this
> subject I have maintained a fairly low profile but now there are many
> here that are furious that nothing beyond individual groups doing COT
> removals has been done. So I find myself reluctantly re-entering the
> discussion of trying to persuade players that should know better, again. I
> am not entering that foray again without published references.
> I am looking for references on any of the following points. I am not
> for an emotional back-and-forth between proponents and opponents of the
> aquarium trade. The coral list has already been used for that.
> Pre-outbreak stimuli
> -Quite a bit of research suggests that COTs thrive in the presence of
> pollution and algae that ensues. A lot of that comes from excessive
> discharges in areas of run-off, like Mele Bay.
> Moreover, further research suggests that nutrient discharges can actually
> stimulate reproduction in COTs, outside of their normal spawning times in
> Dec & Jan (when, by the way, COTs should not be collected because
> handling can trigger early spawning). Other research goes yet further
> and suggests that loss of herbivores and omnivores can stimulate existing
> COTs to eat more, and faster. This happens because in the absence of
> such fish in particular, there is more algae and especially cyanobacteria
> left on the reef. And that brings us back to the first point above, that
> COTs thrive in algae conditions. So its really about what causes the
> not so much as what causes the COTs directly. There is correlation between
> aquarium fish collection and COTs outbreaks with respect to the issue of
> the algae. It makes sense. Albeit this has not conclusively been shown to
> be cause-effect, only a correlation. It is just my personal opinion and
> opinion of others that actually study
> the matter. There is a heck of alot of 'bad' algae around in current fish
> collection areas, particularly in Mele Bay. This might help to explain the
> COT explosion on Efate (fish collection and nutrient pollution) and
> Santo (some nutrient pollution), but not on Epi.
> -Research is not out yet on pelagic and benthic movement of COTs. Some
> people speculate that spawning COTs in Fiji are one reason behind the COTs
> here. I find that a bit far-fetched but who knows? I've seen juveniles,
> not anything near larval stages. Could this be the source for COTs on Epi?
> don't really know. The point is that it doesn't have to be the same reason
> everywhere. Its a mixed bag, as with most disturbances in the marine
> environment. It is also possible that the Epi population came from Efate.
> heard that a few years back it was on Emae, before it hit North Efate.
> Emae to Epi makes sense, but why Emae?
> -It is clear that the Triton shell and the Napoleon are natural predators
> COTs. But is their depletion through local consumption enough to explain
> Epi? I doubt it. Its definitely a contributor though.
> Post-outbreak response
> -It is clear however that coral recruitment on COTs impacted reefs (or any
> impacted reefs that have lost coral) will decrease if hervivores and
> omnivores are in less supply than normal. The algae prevents new coral
> settling. Moreover, dead coral covered in algae breaks off, and
> to loose rubble further limiting coral recruitment not to mention same
> rubble that moves around in surge which damages surviving corals. Thus I
> sincerely believe
> that what we are losing now in terms of coral cover on Efate will not come
> back until herbivore and omnivore fish populations return to normal. Even
> then it will take a long time, considering all the pollution and global
> climate stressors acting concurrently. Even then it may be too little,
> too late. That in my mind is potentially a much more far-reaching issue
> than determining what is causing the outbreak in the first place.
> The latter point is sufficient in my mind to take a good, hard look at the
> impacts of the aquarium trade here in Vanuatu.
> Thank you,
> Karl Fellenius, Director &
> Michele Dricot, Manager
> Vaughani Shores Vanuatu
> Pangona Estates, Efate
> Postal Box 3158
> Port Vila
> office +678 29273 (AWARE)
> mobileK +678 7773329
> mobileM +678 7773326
> email VaughaniShores at vanuatu.com.vu
> web http://www.diveVanuatu.org
> Coral-List mailing list
> Coral-List at coral.aoml.noaa.gov
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