[Coral-List] Long term change in Eritrean reefs: past, present, future
Tupper, Mark (WorldFish)
M.Tupper at CGIAR.ORG
Fri Apr 18 08:22:48 EDT 2008
Dear Tom and listers,
I have been following this thread with some interest after doing a review of GEF-funded coral reef-related projects, which included work in Eritrea. I was wondering the same thing as Tom - if the reefs are so great, why are the fisheries not so great?
Taking a snippet from Tom's post:
"I am one of the scientific advisors to the Manzanar Project, which has planted vast mangrove forests along Eritrean desert shorelines where no mangroves ever existed, using Gordon Sato's innovative approaches, and these have resulted in large increases in catches by local fishermen, which would presumably imply that the reef fisheries habitat is not as pristine as claimed."
I was wondering if anyone knew what species these large catch increases involved. If they were Gerreids or Lutjanids, some species of which have mangrove-dependent life history stages, or other fishes that might be wholly dependent on mangrove habitats, then the increases would result simply from the increase in available mangrove habitat. In that case, the amount of reef (pristine or otherwise) would have no bearing on the catch. However, if the increased catches contained a high proportion of reef fish which maybe using mangrove prop roots as an alternative form of structure/shelter, that might imply (as Tom said) that there was insufficient suitable reef habitat.
Tom, do you have any data on those increased catches, or would you know someone who does?
From: coral-list-bounces at coral.aoml.noaa.gov on behalf of Thomas Goreau
Sent: Fri 4/18/2008 1:35 AM
To: coral-list at coral.aoml.noaa.gov
Cc: Gordon Sato
Subject: [Coral-List] Long term change in Eritrean reefs: past, present,future
> Long term change in Eritrean reefs: past, present, future
I'm wondering why this very interesting article on Eritrea's reefs
just posted on the list server ends with the word "Advertisement"?
Could that be because every place in the world is advertising their
reefs as "pristine" to attract tourists, whether that is true or not?
In the early 1960s the late Thomas F. Goreau did a lot of work on
Eritrean reefs, especially in the Dahlak Arhipelago. To his surprise
he found the coral cover was very low. That was where he discovered
the feeding mode of Acanthaster planci, extruding its stomach to
digest coral tissue, something he had not seen when he collected the
first live Acanthaster intact at Bikini Atoll in 1947, when they
lived deep in crevices and only came out to feed at night (they were
previously known from dredge haul samples and nothing was known of
their ecology). He attributed the low coral cover he found in Eritrea
to chronic infestation by Acanthaster swarms. This was long before
the "first" outbreaks that he, Rick Chesher, and Rick Randall studied
in the Western Pacific in the late 1960s. I have all the photos and
scientific specimens, but I have never found anyone interested in
comparing them to look at long term change.
Now if the report below is correct, and I completely trust Charlie
Veron''s assessment, this implies that the severe Acanthaster
predation that was there 4-5 decades ago has disappeared completely
and permanently? If so, that is truly remarkable, and deserves much
further work because all across the Indo-Pacific we have been seeing
recurrent infestations and nobody has any idea how to control them.
It should also be noted that mapping the Bleaching HotSpots (sensu
Goreau & Hayes, 1994) shows that there should have been several very
severe bleaching events there in recent decades. I have several times
alerted researchers in Eritrea to look out for them, but never
received any field confirmation. The long term sea surface
temperature trends for Eritrea (which I can supply on request)
suggest that worse lies ahead since maximum temperatures in this
region is warming considerably faster than the global ocean average
(Goreau et al, 2005).
Another interesting point about this article below is that if the
reefs are so good everywhere in Eritrea, why have the fisheries
declined? I am one of the scientific advisors to the Manzanar
Project, which has planted vast mangrove forests along Eritrean
desert shorelines where no mangroves ever existed, using Gordon
Sato's innovative approaches, and these have resulted in large
increases in catches by local fishermen, which would presumably imply
that the reef fisheries habitat is not as pristine as claimed.
It is delightful to hear that Eritrean reefs are "pristine", but this
raises very important issues of long term historical changes, and
almost certainly does not imply immunity to the challenges that
global warming will throw at them. More work is clearly needed.
> Thomas J. Goreau, PhD
Global Coral Reef Alliance
37 Pleasant Street, Cambridge MA 02139
goreau at bestweb.net
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