[Coral-List] COT current status

Karl & Michele michka at fellenius.net
Thu Jan 15 21:23:22 EST 2009

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 a 
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 and 
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 at 
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 is 
such that I believe these hypotheses to be true, although I have not carried 
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 people 
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 looking 
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 nutrient
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 algae,
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 the
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 possibly
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, but
not anything near larval stages. Could this be the source for COTs on Epi? I
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. I
heard that a few years back it was on Emae, before it hit North Efate. From
Emae to Epi makes sense, but why Emae?

-It is clear that the Triton shell and the Napoleon are natural predators of
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 from
settling. Moreover, dead coral covered in algae breaks off, and contributes
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

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