[Coral-List] Bleaching and unknown sponge disease in Tobago

[Jahson B]

Dear listers

In some recent surveys of Tobago's reefs, I have noticed some mild to
moderate coral bleaching on some of our reefs.  But what disturbed me most,
was something that's happening to the Caribbean barrel sponge, *Xestospongia
muta *and the Yellow Tube sponge*, **Aplysina fistularia.** *I'm not sure
what's affecting them, but they are very pale and bleaching to the outside,
from the base go up.  The inside of the *X.muta* and *A. fistularia* are
entirely covered in something (I don't know whether it is fungus or bacteria
or dead tissue), but a thin, tattered looking  mat of white membranous
(easily torn by touch) tissue.  Some sponges were dying and started breaking
off at the base and tops.  Others however, had something bright orange and
bright yellow growing beneath the white mat. I can have pictures available
on request. The was observed mainly on the north eastern reefs between
25-40ft.  I did not observe any such sponge disease below 40ft.  Together
with unusually warmer waters, during the last month we have also been affect
by some heavy run off from the South American continent, to the extent that
the fist 10-30ft on some locations were all brown water, and below which was
"green clean".

Regards
Jahson Alemu I
Coral Reef Ecologist

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