[Coral-List] Bleaching Havens

[Paul Muir]

I was wondering if people have investigated ways to protect small areas of
reef from warm water bleaching events. We were recently in the west Indian
Ocean and were quite surprised at how slowly the reefs are recovering from
the '98 bleaching event - at least by our (GBR) standards. We attributed
this slow recovery to the severity of the bleaching (95% + in many places)
and the isolated nature of the reefs - presumably this would have meant that
larval supply available for recovery was initially very low.  In many places
for example, all the Acroporas we saw were post-98 recruits. Given this slow
recovery it begs the questions:  (a) what if there's two such events within
a few years (b) have there already been local extinctions and (c) can
anything be done to get a faster rate of recovery?  

I understand that warm water bleaching coral mortality can sometimes be
reduced by reducing solar irradiation? If so it would be relatively "easy"
to shade small areas of reef for short periods of time during the warm water
event using a plastic fabric that is used in greenhouses (ironic!) and dam
covers. The fabric is light, inexpensive, tough, it floats and is easily
welded or sewn - fitted with air pockets it would be quite possible to make
a portable, floating cover which could shade several hundred square meters
of reef for short periods. Not sure if this would work (it might make it
hotter!!) but some type of 'haven' could provide a source of recruits/
larvae- speeding recovery and possibly reducing localised extinction of
rarer species in isolated reef systems.


Dr. Paul Muir
Museum of Tropical Queensland, 
78-104 Flinders St, 
Townsville QLD 4810 Australia. 
ph 07 47 260 642 fax 07 47 212 093