[Coral-List] Long term change in Eritrean reefs: past, present, future
mateweberhan at wcs.org
Sun Apr 20 20:26:05 EDT 2008
Thanks Peter Raines for bringing Eritrean coral reefs on the list.
It is hardly surprising that the news has been met with different views and even with suspicion given how little is known about Eritrean reefs. My take on the report is that it is very newsy and gives little scientific information. The 'pristine' status in the report highlights the low level of exploitation of the marine resources as the fisheries remains largely of subsistence. Industrial fisheries, large scale tourism and pollution are insignificant except near the two port towns, mainly due to war and underdevelopment of infrastructure. The subject of tolerance to climate change is more contentious. In situ sea water temperatures reach 37oC (average 34 oC) in summer at 3 m (Ateweberhan et al. 2006; Coral Reefs), way higher than those that killed most of the western Indian Ocean reefs in 1998. Shallow waters on many reefs are still dominated by bleaching susceptible taxa, such as Acropora, Montipora or Stylophora. I must say that coral bleaching is very common (1998, 2000
, 2002, 2005) but is often followed by fast recovery. Our unpublished results, based on trends in SST variability and bleaching mortality due to the 1998 ENSO, southern Red Sea reefs are classified among the least vulnerable Indian Ocean reefs.
I would like to point out that both the 1962 and 1965 Israeli Expeditions to the Dahlak were confined to a small area of the Archipelago and focused mainly on invertebrates and macroalgae. They were very descriptive and less exhaustive on both taxonomic and ecological aspects. Even for one of he most conspicuous fish families, such as Chaetodontidae, the published reports from the expedition were less exhaustive (http://dissertations.ub.rug.nl/FILES/faculties/science/2003/z.a.zekeria/thesis.pdf). The above study found 11 species (the highest in the Red Sea). For seaweeds that were extensively surveyed in 1962/65, the report that took nearly 40 years to publish (Silva and Lipkin 2002) presented no. of species that is lower by ~30 than the one reported by Ateweberhan and Prud'homme van Reine (Blumea 2005)for the same area. And the outcome of Charlie Veron's 2007 expedition says it all. With a staggering 225 species (previous record of 115 species for the entire southern Red Sea)and expected 1 new genus and 5 new species, the expedition has again highlighted the large gap of knowledge.
I must admit that even with the present scientific information it is very hard to come up with a clear picture about Eritrean reefs. It is also very hard to conclude on the pristine state of the reefs without a proper scientific investigation based on experimental fishing, proper reporting of landing and modelingsee Tsehaye and Nagelkerken 2008; Ecol Model 212: 319-333). Similarly, proper assessments of the coral and zooxanthellae community structure are needed for tolerance/adaptation (to future climate change) investigation. I hope the discussion will be an opener for promoting general awareness about Eritrean reefs and their proper management.
I guess the subject has very little connection with Gordon Sato's Manzanar Project. I am glad that Sato's Manzanar project is bearing some fruit after shifts in ideas and projects from mullet to milkfish, brine shrimp to spirulina culture and finally to mangrove afforestation during the last ~20 years Sato has been in the country. Only Sato himself and those around him know about the number of skinny goats, the number of plastic containers and concrete blocks that have littered the coasts of Massawa. Only the gods know about the ecological effects of the diammonium phosphate that has leaked into the reefs and the introduced brine shrimp species, mangrove (Rhizophora mangal), Spirulina sps... It is also very hard to swallow his 'low nutrient theory' for an area with one of the highest nutrient levels and primary productivities in tropical seas. Sorry, for inviting the listers to Eritrean politics but what famished Eritreans want is to be left alone (not even fed) for there is no lack of resources.
Phil Dustan wrote:
> Mark and Tom'
> Have a look at Gordon Sato's work on the Manzanar Project - which
> was opposed by GEF COnsultants. Might shed some light on the issues.
> Tupper, Mark (WorldFish) wrote:
>> 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?
>> 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
>> Global Coral Reef Alliance
>> 37 Pleasant Street, Cambridge MA 02139
>> goreau at bestweb.net
>> Coral-List mailing list
>> Coral-List at coral.aoml.noaa.gov
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