[Coral-List] mass coral bleaching in American Samoa

[Douglas Fenner]

    American Samoa has a mass coral bleaching event underway, as predicted
by the NOAA Coral Watch program website.  Currently, several species are
widely bleached on the reef flats and in the back reef pools.  Several
species of staghorns, and a couple species of branching Millepora (fire
coral) are heavily and widely bleached.  At some sites, all branching
Millepora and almost all staghorns are bleached. Most of these are strongly
bleached.  Staghorns dominate or co-dominate many of the reef flat and back
reef pool sites.  At other sites most staghorns are at least partly
bleached.  A variety of other coral species have at least a few colonies
partially bleached, and some coral species have little or no bleaching.
Finger coral, Porites cylindrica, co-dominates some of the sites, but shows
little if any bleaching so far.  At some sites, some of the heavily
bleached staghorns have begun to die, with up to about 10% mortality at
this point.  I've been surveying reef flats and pools, but have seen just
the top of one slope site so far, which wasn't bleached.  A variety of
other people have seen the bleaching on reef flats and in pools as well.
Alice Lawrence and Mareike Sudek from the American Samoa Dept. Marine &
Wildlife Resources have just returned from the small out island of Ofu, and
reported light scattered bleaching in the pools there (which have few
staghorns), mainly in branching Millepora.  Wendy Cover from the National
Marine Sanctuary reports that the slope at Fagatele Bay, part of the
American Samoa National Marine Sanctuary, has scattered partially bleached
colonies.  She says at another site the slope had very little
bleaching.  So far there are no reports I know of, of widespread bleaching
on the slopes.  Staghorns are not common on the reef slopes.

     Staghorns and branching Millepora on reef flats and pools bleach
partially nearly every summer in American Samoa, but this is far more
bleaching than I've seen in my eleven years living on and studying these
islands.  There were bleaching events here in 1994, 2002, and 2003, and I
arrived soon after the last of those.  Goreau and Hayes wrote a report for
the 1994 bleaching event, but there is no written report for either the
2002 or 2003 events.

     The NOAA Coral Reef Watch predictions for American Samoa are pretty
dire, it looks as though in the coming months we will reach the highest
categories they have for levels of thermal stress on corals.  It appears we
are now in the early stages of this mass bleaching event in American
Samoa.  It seems highly likely that it will get much worse in the coming
months, based on the NOAA Coral Reef Watch predictions.  My own guess is
that we will probably have extensive mortality on the reef flats and in the
backreef pools, and extensive bleaching on the reef slopes.  But it is only
a guess.  I hope we don't have extensive mortality on the reef slopes, but
that is also a possibility.  Only time will tell.

     The NOAA Coral Reef Ecosystem Division just arrived here on a NOAA
ship, for a long-planned monitoring survey of the reef slopes here in
American Samoa, they will be recording data from all of the islands of
American Samoa.  They will be recording coral bleaching on the slopes.  It
is fortunate that their long planned cruise here coincides with this
bleaching event.



My surveys of bleaching on the reef flats and in the pools are supported by
the Climate Foundation, which is led by Dr. Brian von Herzen.


Cheers,  Doug


Fenner, D., and S. Heron.  2009.  Annual summer mass bleaching of a
multi-species coral community in American Samoa.  Proceedings of the
11th International
Coral Reef Symposium, Ft. Lauderdale. 1289-1293.

    http://www.nova.edu/ncri/11icrs/proceedings/files/m25-04.pdf#zoom=100m

-- 
Douglas Fenner
Contractor with Ocean Associates, Inc.
PO Box 7390
Pago Pago, American Samoa 96799  USA

phone 1 684 622-7084

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blog: http://ocean.si.edu/blog/reefs-american-samoa-story-hope