[Coral-List] black reefs

Forest Rohwer frohwer at gmail.com
Thu Sep 8 13:26:59 EDT 2011

First, we are very aware that the shipwrecks are often not problems in
the way we've observed in the Line Islands. I have been very careful
to state that iron is only a problem in areas where it is a limiting
nutrient (e.g., strict carbonate platforms in the iron limited parts
of the ocean). If you have an iron source (like an emergent island),
then we don't expect this to be a problem (e.g. Hawaii). All of Dr.
Birkland's examples support our argument.

Chuuk (Truk) Lagoon (Caroline Islands) - emergent islands and no black reefs
Apra Harbor in Guam - BIG emergent island and no black reefs
Pago Pago Harbor - emergent island and no black reefs
Beqa Lagoon, Fiji - emergent island and no black reefs

Rose Atoll - not an emergent island and has a black reef phenotype

Second, iron-enriched shipwrecks are major problems on non-emergent
islands in the iron-limited regions of the ocean. These include
Kingman and Palmyra reefs, which are some of the most near-pristine
reefs on the planet and under USA protection. We (i.e., the USA)
should be working to preserve these sites, EVEN if they are not
guaranteed to survive future global climate changes.

Third, Dr. Birkland's assertion that identifying and working on local
stresses to coral reefs is not important is very short sighted. There
is a very good chance that local conservation efforts will increase
resilience to global stressors. Even if this isn't true, it is
patently obvious that if the reefs are killed off by local stressors
they stand no chance of surviving acidification.

Fourth, even if we are completely wrong about the iron-enrichment
hypothesis, there is no denying that the shipwrecks are devastating.
One-tenth of Fanning Atoll outer reef has been turned into a black
reef. Kingman has lost >1km of the lagoon. Millennium, an amazingly
wonderful atoll, has lost >1 km of the outer reef. All of these are
shipwreck sites.

Finally, we have gotten useful feedback from a number of groups
reporting black reefs associated with shipwrecks or NO black reefs
associated with shipwrecks from different parts of the world. I would
very much like to compile these observations into a GIS database. So,
if you have observational data where you would have noted a black reef
phenotype, or a shipwreck without this phenotype, can you please email
notes, photos, etc and location (preferably GIS coordinates) to Nao
Hisakawa <nghisakawa at gmail.com>.

Thank you in advance,

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