[Coral-List] Long term change in Eritrean reefs: past, present, future

[Tupper, Mark (WorldFish)]

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?

Cheers,

Mark Tupper




-----Original Message-----
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
President
Global Coral Reef Alliance
37 Pleasant Street, Cambridge MA 02139
617-864-4226
goreau at bestweb.net
http://www.globalcoral.org